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Purpose: This article describes subtype diversity among diagnosed HIV-1 infections in the United States during 2008-2016 by demographic or risk group and over time., Methods: HIV-1 polymerase sequences reported to the National HIV Surveillance System for persons in 17 U.S. states with HIV infection diagnosed during 2008-2016 were subtyped using COMET, an automated subtyping tool, and National HIV Surveillance System demographic data were analyzed., Results: Subtype B was identified in 93.6% of 121,793 reported sequences. The most common non-B subtypes and circulating recombinant forms (CRFs) were C, CRF02_AG, A, CRF01_AE, and G. Elevated percentages of non-B subtypes or CRFs were found in persons who were female, aged less than 13 years at diagnosis, Asian, or had transmission attributable to heterosexual contact (females only) or perinatal exposure. Foreign-born persons had a higher percentage of non-B subtypes. The prevalence of non-B subtypes and CRFs increased from 5.0% in 2008 to 8.5% in 2016; among specific subtypes and CRFs, subtype G and CRF01_AE increased., Conclusions: Subtype B remains the predominant strain in the United States. Non-B subtypes and CRFs were not widespread, but diversity and numbers increased from 2008 through 2016, which could have consequences for clinical management, diagnostic testing, and vaccine development., (Published by Elsevier Inc.)

Background: Methylphenidate (MPH) influences catecholaminergic signaling. Extant work examined the effects of MPH on the neural circuits of attention and cognitive control, but few studies have investigated the effect of MPH on the brain's resting-state functional connectivity (rsFC)., Methods: In this observational study, we compared rsFC of a group of 24 healthy adults who were administered an oral 45 mg dose of MPH with a group of 24 age and gender matched controls who did not receive MPH. We focused on three seed regions: basal nucleus of Meynert (BNM), locus coeruleus (LC), and ventral tegmental area/substantia nigra, pars compacta (VTA/SNc), each providing cholinergic, noradrenergic and dopaminergic inputs to the cerebral cortex. Images were pre-processed and analyzed as in our recent work (Li et al., 2014; Zhang et al., 2015). We used one-sample t-test to characterize group-specific rsFC of each seed region and two-sample t-test to compare rsFC between groups., Results: MPH reversed negative connectivity between BNM and precentral gyri. MPH reduced positive connectivity between LC and cerebellum, and induced positive connectivity between LC and right hippocampus. MPH decreased positive VTA/SNc connectivity to the cerebellum and putamen, and reduced negative connectivity to left middle occipital gyrus., Conclusion: MPH had distinct effects on the rsFC of BNM, LC, and VTA/SNc in healthy adults. These new findings may further our understanding of the role of catecholaminergic signaling in Attention Deficit Hyperactivity Disorder (ADHD) and Parkinson's disease and provide insights into the therapeutic mechanisms of MPH in the treatment of clinical conditions that implicate catecholaminergic dysfunction.

Context: During a mass smallpox immunization campaign, vaccine may be exposed to ambient temperatures for extended periods of time., Objective: To determine the viability of undiluted and 5x diluted DryVax smallpox vaccine after cycling vaccine in and out of refrigeration for 2 weeks, as might occur during an immunization campaign., Design: Two vials of Dryvax vaccine were reconstituted as per manufacturer's instructions (1x) and two vials were reconstituted using 5x the recommended diluent (5x). Every 12h over 2 weeks, vials were cycled between refrigeration and room temperature (1x-RT, 5x-RT) or ice bath (1x-cold, 5x-cold). Each vial was sampled in triplicate at time of reconstitution and thereafter at 24 or 48 h intervals., Main Outcome Measures: Viability measured by viral plaque forming units per ml (pfu/ml)., Results: All four vaccine vials showed a decline in virus titer over the 2-week period but remained well above 10(7)pfu/ml. Compared with titers on the day of reconstitution (day 0), titers at the end of the study (day 14) had declined by 0.4--0.6l og in all vials (Table 1). Linear regression analysis suggested that decay in viral titer occurred more rapidly in vials exposed to room temperature compared with vials kept on ice and in vaccine diluted 1x compared with vaccine diluted 5x., Conclusions: After 2 weeks, viability was greater than 10(7)pfu/ml, the titer suggested by Frey et al. as necessary to ensure successful vaccination in more than 97% of vaccinees. When removed from refrigeration, keeping the vaccine on ice lowers the decline in titer.

Objective: To document the nature and prevalence of tobacco promotions in bars and clubs in a major US city., Design: We conducted systematic observations in a representative sample of 38 establishments in the Boston area, half of which had been advertised in a tobacco company ad. We also observed seven events in six additional clubs hosting Camel Casbah promotions. Telephone interviews were later completed with club managers., Main Outcome Measure: Use of branded give-away items, distribution of free cigarette samples, managers' reports of costs and benefits of hosting promotions., Results: The majority of the 38 clubs were observed to use bar paraphernalia including matchbooks with tobacco brand logos, regardless of their history of appearing in tobacco sponsored ads. Free cigarette samples were not observed at any of the sampled clubs, but were a feature of every Casbah event. Managers of clubs in the advertised group were somewhat more likely to report having hosted promotions, but 44% of managers of non-advertised clubs indicated that tobacco promotions had occurred in their establishments in the past. Approximately one third of club managers viewed public links with a tobacco company as a negative feature of hosting promotions., Conclusions: Based on managers' reports, tobacco promotions occurred in more than 50% of the Boston area entertainment venues frequented by young adults. Cigarette companies should be required to inform the attorney general of plans to conduct promotions in adult-only venues to facilitate monitoring of compliance with the Master Settlement Agreement. The negative health and business consequences of hosting promotions should be communicated to bar owners.

Background: The outbreak of monkeypox in the Midwestern United States during June 2003 marks the first documented human infection in the Western Hemisphere. Consistent with those in outbreaks in Africa, most cases in this outbreak were associated with febrile rash illness. We describe a cluster of monkeypox in a family with a spectrum of clinical illness, including encephalitis, and outline the laboratory confirmation of monkeypox., Methods: Standardized patient information was collected by questionnaire and medical chart review; all cases described were laboratory confirmed. Laboratory methods included nucleic acid detection, viral culture, serologic testing, histopathologic evaluation, and immunohistochemical testing., Results: Of 3 family members with monkeypox, 2 had rash illness only, and 1 required hospitalization for severe encephalitis. The family member with the mildest clinical course had previously received smallpox vaccination. Diagnostic testing by both polymerase chain reaction and culture revealed infectious monkeypox virus in skin lesions of all 3 patients; 2 patients had orthopoxvirus detected by immunohistochemistry in skin lesions. The patient with encephalitis had orthopoxvirus-reactive immunoglobulin M (IgM) in cerebrospinal fluid. All patients had detectable IgM responses to orthopoxvirus antigens., Conclusions: These 3 patients illustrate a spectrum of clinical illness with monkeypox despite a common source of exposure; manifestation and severity of illness may be affected by age and prior smallpox vaccination. We report that monkeypox, in addition to causing febrile rash illness, causes severe neurologic infection, and we discuss the use of novel laboratory tests for its diagnosis.

The kidney plays a critical role in regulating the level of arterial pressure and in the pathogenesis of hypertension. Important evidence has come from studies in which hypertension is generated by transplanting kidneys from genetically hypertensive rats into normotensive recipients, suggesting that the level of blood pressure is strongly influenced by the genetic background of the kidney. We hypothesized that pharmacotherapy could modify specific properties intrinsic to the kidney such that after transplantation, there would be persistent changes in the level of arterial pressure. We determined that angiotensin-converting enzyme inhibitor treatment (enalapril) in spontaneously hypertensive rats induced both a persistent 17% reduction of mean arterial pressure and a persistent change in the kidney. This persistent change in the circulation could be completely transferred to untreated spontaneously hypertensive rats by kidney transplantation; ie, mean arterial pressure in untreated spontaneously hypertensive rat recipients was persistently lowered after transplantation of a kidney from a previously treated spontaneously hypertensive rat donor. In addition, the persistent lowering of mean arterial pressure after enalapril treatment could be completely abolished by implanting an untreated kidney, thereby revealing the importance of the kidney-specific changes. Furthermore, after within-group transplantations, there were no changes in the level of arterial pressure; ie, a 16% difference in mean arterial pressure remained between the 2 groups. The findings revealed that drug-induced changes specific to the kidney determined the level of arterial pressure, thereby suggesting the kidney should be a key therapeutic target for pharmacotherapy.

The present study assessed the short- and long-term effect of tempol, a membrane-permeable mimetic of superoxide dismutase, on renal medullary hemodynamics in spontaneously hypertensive rats (SHR). Tempol was given in the drinking water (1 mM) for 4 days or 7 wk (4-11 wk of age), and medullary blood flow (MBF) was measured over a wide range of renal arterial pressure by means of laser-Doppler flowmetry in anesthetized rats. In addition, the response of the medullary circulation to angiotensin II (5-50 ng x kg(-1) x min(-1) iv) was determined in SHR treated for 4 days with tempol. Compared with control SHR, short- and long-term treatment with tempol decreased arterial pressure by approximately 20 mmHg and increased MBF by 35-50% without altering total renal blood flow (RBF) or autoregulation of RBF. Angiotensin II decreased RBF and MBF dose dependently (approximately 30% at the highest dose) in control SHR. In SHR treated with tempol, angiotensin II decreased RBF (approximately 30% at the highest dose) but did not alter MBF significantly. These data indicate that the antihypertensive effect of short- and long-term administration of tempol in SHR is associated with a selective increase in MBF. Tempol also reduced the sensitivity of MBF to angiotensin II. Taken together, these data support the idea that tempol enhances vasodilator mechanisms of the medullary circulation, possibly by interacting with the nitric oxide system. Increased MBF and reduced sensitivity of MBF to angiotensin II may contribute to the antihypertensive action of tempol in SHR.

This study tested the hypotheses that renal medullary blood flow (MBF) in spontaneously hypertensive rats (SHR) has enhanced responsiveness to angiotensin (ANG) II and that long-term treatment with enalapril can correct this. MBF, measured by laser Doppler flowmetry in anesthetized rats, was not altered significantly by ANG II in Wistar-Kyoto (WKY) rats, but was reduced dose dependently (25% at 50 ng. kg(-1). min(-1)) in SHR. Infusion of N(G)-nitro-L-arginine methyl ester (L-NAME) into the renal medulla unmasked ANG II sensitivity in WKY rats while L-arginine given into the renal medulla abolished the responses to ANG II in SHR. In 18- to 19-wk-old SHR treated with enalapril (25 mg. kg(-1). day(-1) when 4 to 14 wk old), ANG II did not alter MBF significantly, but sensitivity to ANG II was unmasked after L-NAME was infused into the renal medulla. Endothelium-dependent vasodilation (assessed with aortic rings) was significantly greater in treated SHR when compared with that in control SHR. These results indicate that MBF in SHR is sensitive to low-dose ANG II and suggest that this effect may be due to an impaired counterregulatory effect of nitric oxide. Long-term treatment with enalapril improves endothelium-dependent vascular relaxation and decreases the sensitivity of MBF to ANG II. These effects may be causally related to the persistent antihypertensive action of enalapril in SHR.

Objective: To describe legal theories that non-smoking residents of multiple occupancy buildings may employ when affected by environmental tobacco smoke (ETS) from neighbouring units., Design: Legal research was conducted in several US states. Research was performed among statutes and regulations. State health regulations were examined as well as common law claims of nuisance, warranties of habitability, and the right of quiet enjoyment., Results: Through the use of state regulations, such as a sanitary code, several states provide general language for protecting the health of residents in multi-unit buildings. State law also supports more traditional claims of nuisance, warranties of habitability, and the right of quiet enjoyment., Conclusions: The use of state regulations has the potential to provide an effective, existing vehicle for resolution of ETS incursion problems. The general health protection language of the regulations, in conjunction with the latest evidence of the harmful effects of ETS, gives state agencies authority to regulate environmental tobacco smoke incursions among apartments in multi-unit dwellings. Where state regulations are not available, other common law legal remedies may be available.

We describe a laboratory experience for upper-level science students that provides a hands-on approach to understanding the basics of experimental physiology. A pre-lab, interactive tutorial develops the rationale for this experiment by reviewing the renal and cardiovascular mechanisms involved in the response to extracellular fluid volume expansion. After a hypothesis is stated, an experiment is designed to determine the relative importance of dilution of plasma proteins to the overall renal excretory response following volume expansion with intravenous saline. In the lab, students collect data from two groups of anesthetized rats. The protocol involves continuous monitoring of arterial pressure and periodic collection of urine and blood samples after volume expansion with either isotonic NaCl or isotonic NaCl plus 5% albumin. A post-lab tutorial is used to analyze, interpret, and discuss the data. Students next prepare an oral presentation, practice it, and finally present their results and answer questions before peers and instructors. This overall experience involves all of the components of doing a "real" experiment, starting with a question that is not answered in general textbooks of physiology and finishing with an oral presentation of the results. Along the way, students gain a better understanding of a complex homeostatic response and learn the care and value of using animals in research and teaching.

Long-term angiotensin-converting enzyme (ACE) inhibition in the spontaneously hypertensive rat (SHR) resets pressure natriuresis and shifts the relationship between renal arterial pressure (RAP) and renal interstitial hydrostatic pressure (RIHP) to lower levels of arterial pressure. These effects persist after withdrawal of treatment. The purpose of this study was to determine the effect of short- and long-term ACE inhibition on medullary blood flow (MBF). Enalapril (25 mg. kg-1. day-1 in drinking water) was given to male SHR from 4 to 14 wk of age. Four weeks after stopping treatment, we measured MBF over a wide range of RAP using laser-Doppler flowmetry in anesthetized rats. Additional rats, either untreated or previously treated for 10 wk, received 3-day enalapril treatment just before the experiment. MAP (mmHg +/- SE) was 178 +/- 6 (n = 8), 134 +/- 6 (n = 8), 138 +/- 5 (n = 9), and 111 +/- 6 mmHg (n = 9) for the untreated, 3 day, 10 wk, and 10 wk + 3 day groups, respectively. Total renal blood flow for the groups receiving 3-day treatment was significantly higher when compared with that in rats with an intact renin-angiotensin system. Three-day treatment had no effect on the relationship between RAP and RIHP, whereas that in rats receiving 10-wk treatment was shifted to lower levels of RAP by approximately 30 mmHg. Both 10-wk and 3-day treatment independently increased the slope of the RAP versus MBF relationship at values of RAP > 100 mmHg. The slopes in perfusion units/mmHg were 0.12 +/- 0.01 (n = 8), 0.26 +/- 0.01 (n = 8), 0.27 +/- 0.01 (n = 9), and 0.30 +/- 0.02 (n = 9) for the untreated, 3 day, 10 wk, and 10 wk + 3 day groups, respectively. These results indicate that the effect of short-term and the persistent effect of long-term enalapril alter renal medullary hemodynamics in a way that may contribute to the resetting of the pressure-natriuresis relationship in treated rats.

Previously, changes in position and slope of the pressure-natriuresis relationship have been used to characterize antihypertensive drugs in basic research. Rilmenidine may chronically reduce arterial pressure via central nervous system and renal imidazoline receptors. The present experiments were used to examine the shift in the pressure-natriuresis relationship during rilmenidine administration. We examined the effects of twice daily doses (1 and 3 mg/kg) for 6 days on the pressure-natriuresis relationship determined for control and treated spontaneously hypertensive rats (SHR) drinking tap water or 1% NaCl. The pressure-natriuresis relationship was shifted to the left for the 3 mg/kg dose and the slope was no different from the control. These experiments also indicated that rilmenidine might have an effect on sodium preference which was confirmed in a third series of experiments by permitting control and treated (3 mg/kg) SHR access to both tap water and 1% NaCl. This lack of change in slope indicates that, during rilmenidine treatment, the arterial pressure is relatively insensitive to sodium intake. The shift to the left indicates a restoration of the pressure-natriuresis relationship after chronic treatment with rilmenidine and a resetting of the long-term blood pressure control. Rilmenidine also reduces salt appetite in the SHR.

Objective: NG,NG-dimethylarginine (asymmetric dimethylarginine, ADMA) is an important endogenous substance with potent inhibitory actions on nitric oxide (NO) synthesis. The present study was designed to determine circulating ADMA levels and endothelium-dependent, NO mediated vasodilation in a rat model of congestive heart failure (CHF)., Methods: CHF was induced in rats by coronary artery ligation. Sham-operated rats served as normal controls. Plasma ADMA was determined by high performance liquid chromatography with fluorescence detection. Glomerular filtration rate (GFR) and renal blood flow (RBF) were measured by the clearance of inulin and p-aminohippuric acid, respectively. Endothelial function of the aorta was assessed in an organ bath., Results: Plasma levels of ADMA in rats with CHF (0.94 +/- 0.05 mumol/l) were significantly increased compared with sham-operated controls (0.75 +/- 0.06 mumol/l, p < 0.05). Plasma levels of ADMA was negatively correlated with GFR (r = -0.65, p < 0.05). Decreased endothelium-dependent relaxation to acetylcholine in the aorta of CHF was completely restored by L-arginine (300 microM) (p < 0.01) while endothelium-independent relaxation to nitroprusside was not altered. ADMA potently inhibited endothelium-dependent relaxation in thoracic aorta of normal and CHF rats. The effect of ADMA was completely antagonized by L-arginine in both groups (p < 0.01). Moreover, L-arginine improved endothelium-dependent relaxation in CHF rats in the presence of ADMA., Conclusions: An endogenous NO synthesis inhibitor ADMA is increased in the circulation of rats with CHF. The increased plasma levels of ADMA may contribute to the decreased endothelium-dependent relaxation in CHF, which is restored by L-arginine, possibly by competitive antagonism of ADMA.

Long-term angiotensin-converting enzyme inhibitor treatment has been shown to have a persistent antihypertensive effect in spontaneously hypertensive rats (SHR) long after discontinuation of treatment. To test the hypothesis that this persistent effect involves a shift in the pressure-natriuresis relation, we performed experiments in male, anesthetized SHR at 18 wk of age with fixed neural and hormonal influences on the kidney. Renal function was assessed at various levels of arterial pressure using standard clearance techniques. Enalapril (25 mg.kg-1.day-1 in drinking water) was administered from 4 to 14 wk of age and again 3 days before renal function studies. The following four groups of SHR were studied: 1) 10-wk treatment, 2) 10-wk + 3-day treatment, 3) 3-day treatment, and 4) untreated. Groups 1 and 4 had an intact renin-angiotensin system; groups 2 and 3 had the renin-angiotensin system blocked. Mean arterial pressure (MAP, mmHg; means +/- SE) under Inactin anesthesia was 139 +/- 4 (n = 9), 109 +/- 3 (n = 8), 149 +/- 1 (n = 9), and 181 +/- 7 mmHg (n = 9) for each of the four groups, respectively. Glomerular filtration rate was similar in all groups at resting levels of MAP, whereas renal blood flow was elevated in all treatment groups when compared with that in untreated SHR. Pressure-natriuresis, pressure-diuresis, and pressure-fractional sodium excretion curves for the 10-wk treatment group and 3-day only treatment group were shifted leftward to significantly lower pressures by approximately 25 mmHg, compared with the untreated group. The curves for the treated +3-day group were shifted an additional 30 mmHg to the left. The relationship between renal artery pressure (RAP) and renal interstitial hydrostatic pressure was also shifted 25-30 mmHg but only in rats that received the long-term treatment with enalapril. Three-day enalapril had no significant effect on this relationship. These data indicate that the persistent effect of long-term enalapril treatment on arterial pressure in SHR is the result of a shift in the pressure-natriuresis relationship. The mechanism for this effect involves hemodynamic changes that act to improve transmission of RAP to the interstitium, resulting in enhanced sodium excretion for a given level of RAP.

Rilmenidine is an antihypertensive agent acting at the imidazoline receptor that may have both central effects in the ventral lateral medulla and direct effects on the kidney to alter Na+ excretion. The present experiments examined whether rilmenidine induces a leftward shift or change in the slope of the pressure-natriuresis curve in the spontaneously hypertensive rat (SHR). A single oral gavage dose indicated that 3 and 10 mg/kg rilmenidine significantly lowers arterial pressure at 4-12 h after administration by oral gavage. The effect of rilmenidine on pressure-natriuresis was studied using twice daily doses of 1 and 3 mg/kg for control and treated SHR drinking tap water or 1% NaCl for 3 days. Na+ excretion was measured over 24 h, and mean arterial pressure was measured 6-8 h after the morning dose of rilmenidine. The results indicate that 1 mg/kg had no effect, while the pressure-natriuresis relationship for the rats receiving the 3 mg/kg dose was shifted to the left and was not significantly different from the vertical slope of the untreated SHR. This experiment also suggested that rilmenidine may attenuate the salt preference of the rats. This was confirmed in an additional series of experiments in which the rats had access to both tap water and 1% NaCl. Thus, rilmenidine shifts the pressure-natriuresis relationship to the left and reduces salt preference in SHR.

Stanniocalcin (STC) is a glycoprotein hormone first identified in bony fishes where it counteracts hypercalcemia by inhibiting gill calcium uptake and stimulating renal inorganic phosphate (Pi) reabsorption. Human STC (hSTC) has recently been cloned and sequenced and is highly homologous to the fish hormone at the amino acid level. The objective of this study was to examine the possible effects of hSTC on electrolyte homeostasis and renal function in the rat. Recombinant hSTC was expressed in bacteria and purified by metal-ion affinity chromatography and reverse-phase high performance liquid chromatography. Anesthetized animals were given bolus infusions of 1, 5, or 10 nmol hSTC per kilogram of body weight. Control animals received solvent alone. The most effective dosage was 5 nmol/kg, which caused significant reductions in both absolute and fractional phosphate excretion in comparison with control rats. The hSTC had no effect on the renal excretion of other ions, the glomerular filtration rate, renal blood flow, blood pressure, or plasma electrolytes (Na+, K+, Ca2+, Pi, Mg/+). The maximum effect of hSTC on phosphate excretion was observed 60-80 minutes postinjection. Lesser effects were obtained with higher and lower dosages of hormone. When renal cortical brush-border membrane vesicles were isolated from control and hormone-treated animals 80 minutes postinjection, the rate of Na+/Pi cotransport was found to be 40% higher in vesicles from hormone-treated animals (p < 0.01; 5 nmol hSTC/kg). Together, the renal clearance and membrane vesicle data indicate that hSTC participates in the renal regulation of Pi homeostasis in mammals.

In a study to determine the reliability, sensitivity, and specificity of the Chiron RIBA HIV-1/HIV-2 Strip Immunoblot Assay (RIBA HIV-1/2 SIA) for confirmation of human immunodeficiency virus type 1 (HIV-1) and HIV-2 antibodies, 1,263 serum samples from various populations in the United States, Caribbean, Africa, India, and Thailand were evaluated by RIBA HIV-1/2 SIA, and the results were compared with those obtained by an HIV-1 Western blot (immunoblot) assay. All sera were tested by HIV enzyme immunoassay, RIBA HIV-1/2 SIA, and Western blotting. Samples with discrepant results were further tested by an HIV-1 and/or HIV-2 immunofluorescent-antibody assay and HIV-1 p24 antigen assay. The RIBA HIV-1/2 SIA detected all 17 HIV-1 and HIV-2 dually reactive serum samples, all 215 HIV-2-positive serum samples, and 480 of 481 HIV-1-positive serum samples for a sensitivity of 99.8%. Of 548 negative samples, 523 were RIBA HIV-1/2 SIA negative, for a specificity of 95.4%, with 22 (4%) samples interpreted as indeterminate and 3 (0.6%) interpreted as falsely positive. Western blotting detected 391 of 548 negative samples (specificity, 71.4%), with 152 (27.7%) samples interpreted as indeterminate and 5 (0.9%) interpreted as falsely positive. In conclusion, the RIBA HIV-1/2 SIA had a sensitivity comparable to that of Western blotting and could discriminate HIV-1 from HIV-2 in one blot, providing a cost advantage. Because of its high degree of specificity, the RIBA HIV-1/2 SIA further reduced the number of indeterminate results found by Western blotting, providing a more accurate means of assessing seronegative individuals.

The endogenous level of L-arginine in renal cortex, outer medulla, and inner medulla and its effect on the measurement of nitric oxide synthase (NOS) activity in these regions was determined. L-Arginine was measured with an amino acid analyzer and total NOS activity was measured as the rate of formation of radiolabeled L-citrulline from L-[14C]arginine. Total NOS activity was that activity inhibited by NG-nitromonomethyl-L-arginine (300 microM). The endogenous L-arginine concentration was 452 +/- 45 (mean +/- SEM), 313 +/- 25, and 95 +/- 8 pmol/mg wet weight in the cortex, outer medulla, and inner medulla, respectively (n = 12). Total NOS activity was 61 +/- 19, 709 +/- 94, and 1347 +/- 76 pmol.h-1.mg protein-1 in the cortex, outer medulla, and inner medulla, respectively, when endogenous L-arginine was not considered in the calculation. Correcting for endogenous L-arginine gave values of 185 +/- 61, 1714 +/- 239, and 1707 +/- 104 pmol.h-1.mg protein-1, respectively. Dowex extraction to remove endogenous L-arginine from samples also increased NOS activity in cortex and medulla. The data indicate that there is a differential distribution of endogenous L-arginine in the kidney and that these levels must be taken into account when measuring NOS activity. NOS activity is also distributed differentially, with activity in the medulla being nearly 10-fold higher than in the cortex.

Nitric oxide has been suggested to be an essential mediator of pressure natriuresis. To investigate this hypothesis, the effect of acute or chronic inhibition of nitric oxide synthase on pressure natriuresis and renal interstitial hydrostatic pressure was studied in anesthetized Sprague-Dawley rats with fixed neural and hormonal influences on the kidney. Both acute infusion (10 micrograms.kg-1.min-1 iv) and chronic administration (50 mg.kg-1.day-1 for 7 days in drinking water) of NG-nitro-L-arginine methyl ester (L-NAME) resulted in significantly increased mean arterial pressure, a 30% decrease in renal blood flow, and no change in glomerular filtration rate when compared with values in control rats. Pressure-diuresis, pressure-natriuresis, and pressure-fractional sodium excretion curves in L-NAME-treated rats were shifted to a higher pressure (by approximately 25 mmHg) when compared with those in control rats. The relationship between renal artery pressure and renal interstitial hydrostatic pressure was shifted similarly in L-NAME-treated rats. Acute administration of L-arginine completely reversed the renal effects of chronic L-NAME. These data indicate that, at the doses used in this study, both acute and chronic inhibition of nitric oxide synthase decreased the ability of the kidney to excrete sodium at least in part by a hemodynamic mechanism leading to an increased filtration fraction and a decreased renal interstitial pressure. The parallel shift of the pressure-natriuresis curve to a higher pressure suggests that nitric oxide is an important modulator but not an essential mediator of the pressure natriuresis.

Rilmenidine binds to alpha 2-adrenoceptors and imidazoline receptors in the central nervous system and the kidney. To test the hypothesis that rilmenidine would increase sodium excretion, renal function was studied in rats with innervated and denervated kidneys to distinguish between indirect (via renal sympathetic nerves) and direct effects of rilmenidine on the kidney. Standard clearance techniques were used in Wistar rats anesthetized with thiobutabarbital to measure renal function during 80 minutes of infusion of 0.9% NaCl or rilmenidine (20 or 50 micrograms.kg-1.min-1 intravenously). Snares on abdominal arteries were used to offset hypotension induced by rilmenidine. Heart rate decreased by 80-120 beats/min with either dose of rilmenidine. At 20 micrograms.kg-1.min-1, rilmenidine increased total and fractional excretion of sodium and clearance of osmoles while decreasing free water clearance from innervated kidneys. There were no changes in these variables in chronically denervated kidneys. Direct recording of renal sympathetic nerve activity showed a progressive, marked decrease in nerve activity during the low-dose infusion of rilmenidine. At 50 micrograms.kg-1.min-1, rilmenidine produced a differential effect on the clearance of osmoles by innervated and denervated kidneys but both kidneys had an increase in free water clearance. The data indicate that rilmenidine increases sodium excretion indirectly in anesthetized rats by decreasing renal sympathetic nerve activity. At doses and infusion periods used in these studies, there was no evidence for a direct effect of rilmenidine on sodium excretion. The increase in free water clearance seen with the high dose of rilmenidine suggests that the inhibitory effect of alpha 2-adrenoceptor activation on vasopressin is involved at this dose.(ABSTRACT TRUNCATED AT 250 WORDS)

The goal of this study was to determine how long-term treatment of spontaneously hypertensive rats with losartan affects the pressure-natriuresis curve. Rats were treated with losartan (12 to 15 mg.kg-1.d-1 in drinking water) starting at 4 to 5 weeks of age. At 8 to 9 weeks of age, pressure natriuresis was studied in treated and untreated anesthetized rats using a preparation involving volume expansion and fixed neural and hormonal influences on the kidney. In some untreated rats, losartan (10 or 30 mg.kg-1 i.v.) was given acutely. Average initial mean arterial pressure (+/- SEM) for untreated rats was 164 +/- 2 mm Hg (n = 13) and 131 +/- 3 mm Hg (n = 13) for rats treated chronically with losartan (P < .01). Short-term losartan did not alter arterial pressure significantly. Glomerular filtration rate was not altered significantly by losartan, and renal blood flow was increased modestly by long- and short-term (10 mg.kg-1) losartan at several levels of renal artery pressure. At renal artery pressures of 130 to 175 mm Hg, there were no significant differences between untreated and short-term losartan rats for urine flow, total and fractional sodium excretions, and renal interstitial hydrostatic pressure. The relation between renal artery pressure and urine flow, sodium excretion, or fractional sodium excretion was shifted to the left by long-term losartan treatment. At identical renal artery pressures, renal interstitial hydrostatic pressure was not significantly different among losartan-treated (short or long term) and respective control groups.(ABSTRACT TRUNCATED AT 250 WORDS)

We evaluated the reliability, sensitivity, and specificity of two rapid assays, TestPack HIV-1/HIV-2 and Genie HIV-1/HIV-2, in Lagos, Nigeria. An alternative algorithm to EIA and Western blot was then examined with the TestPack HIV-1/HIV-2 used as the screening test and the Genie HIV-1/HIV-2 used as the supplemental test to differentiate HIV-1 and HIV-2 infection. In all, 845 prostitutes were evaluated for HIV-1 and HIV-2 infection using one of the two rapid tests and compared to EIA and Western blot results. Of these 845 cases, 437 samples were analyzed by both assays. Overall, 109 (12.7%) prostitutes were antibody positive for HIV-1, 13 (1.5%) for HIV-2, and six (0.7%) were dually reactive for both HIV-1 and HIV-2. Compared to Western blot, the Genie HIV-1/HIV-2 had a slightly higher sensitivity and specificity (98.4% and 99.7%) than the TestPack HIV-1/HIV-2 (97.6% and 99.3%). The alternative algorithm using both rapid assays had a sensitivity of 96.9% and a specificity of 99.9%. The Genie HIV-1/HIV-2 correctly identified 104 of 108 HIV-1 positive sera, 12 of 13 HIV-2 positive sera, and all six dually positive sera. Both assays performed well in the field. They required < 10 min to complete, no equipment, and little training. An algorithm incorporating two rapid assays can be used as a less expensive alternative to traditional testing strategies comparable in reliability to ELISA and Western blot; it provides the additional advantage of differentiating between HIV-1 and HIV-2.

The Genie HIV-1/HIV-2 rapid assay was compared with an enzyme-linked immunosorbent assay and Western blot (immunoblot) by using 540 serum specimens from four different populations. The Genie HIV-1/HIV-2 assay was easy to perform, required no equipment, provided visual results within 10 min, and demonstrated excellent sensitivity and specificity compared with the Western blot.

Angiotensin II (ANG II; 10 or 30 ng/min iv) was infused for 7-10 days in unilaterally adrenalectomized and nephrectomized Sprague-Dawley rats drinking 1% NaCl. The acute pressure-natriuresis relationship was studied under Inactin anesthesia in volume-expanded rats with fixed neurohumoral influences on the remaining kidney. Renal interstitial hydrostatic pressure (RIHP) was measured using a catheter implanted into the renal cortex. Arterial blood pressure before laparotomy was 149 +/- 3 (SE) mmHg (n = 6) and 152 +/- 6 mmHg (n = 16) for ANG II-infused rats (10 and 30 ng/min, respectively) and 123 +/- 5 mmHg (n = 6) and 123 +/- 7 mmHg (n = 16) for the respective control rats. Compared with values in control rats, ANG II-infused rats had significantly (P < 0.05) lower urine flow and absolute and fractional sodium excretion at renal artery pressures of 115-150 mmHg. There were no significant differences between RIHP measured in control and ANG II-hypertensive rats. The shift in the pressure-diuresis, pressure-natriuresis, and pressure-fractional sodium excretion relationships was similar with both doses of ANG II and was reversed by the acute administration of losartan (10 mg/kg iv). In all groups of rats, renal blood flow was autoregulated, whereas glomerular filtration rate was not autoregulated in ANG II-infused rats and was significantly lower than that in control rats at the lower level of renal artery pressure. The data indicate that rats with ANG II-induced hypertension have a rightward shift of the pressure-natriuresis curve caused primarily by a decrease in fractional excretion of sodium. The lack of effect of chronic ANG II infusion on filtration fraction and RIHP suggests that the increased tubular reabsorption was due to a direct action of ANG II on renal tubules. The reversal of these effects by losartan suggests that the shift in the pressure-natriuresis curve in ANG II-induced hypertension is mediated by the AT1-receptor subtype.

Renal function studies using standard clearance techniques were done in control and rilmenidine-infused (20 micrograms/Kg/min i.v. for 80 min) Wistar rats anesthetized with Inactin. The role of renal sympathetic nerves in the action of rilmenidine was assessed using rats in which the left kidney was denervated 7 to 10 days before the experiment. In other experiments, renal sympathetic nerve activity was recorded during infusion of rilmenidine. Arterial pressure and heart rate were decreased significantly by rilmenidine but changes in arterial pressure were limited to 10 to 12 mm Hg by ligating the proximal aorta during infusion of rilmenidine. Under these conditions, rilmenidine did not alter glomerular filtration rate significantly, but renal blood flow increased significantly in both innervated and denervated kidneys. Urine flow, total and fractional sodium excretion, and clearance of osmoles increased significantly in innervated kidneys but not in denervated kidneys. Free water clearance was decreased significantly, but only in the innervated kidney. Potassium excretion and fractional potassium excretion were increased significantly in both kidneys, although the change was larger in the innervated kidneys. Rilmenidine decreased renal sympathetic nerve activity progressively until by 80 min nerve activity was essentially absent. The data indicate that rilmenidine increases renal blood flow and potassium excretion by a mechanism independent of renal nerves, whereas the natriuresis and diuresis is dependent upon intact renal nerves. The increase in fractional excretion of sodium was associated with a marked decrease in renal sympathetic nerve activity suggesting that the natriuresis is caused by decreased tubular reabsorption of sodium subsequent to a central action of rilmenidine.

Because the time from primary infection to symptoms in human immunodeficiency virus type 1 (HIV-1) infection is typically 8-10 years, the use of surrogate markers to monitor disease progression and therapeutic efficacy is of interest. An acid dissociation procedure that disrupts the p24 antigen-antibody complexes found in early HIV-1 infection has greatly increased the sensitivity of p24 detection assays. The utility of p24 antigen after acid treatment as a surrogate marker of disease progression and therapeutic effect in asymptomatic HIV-infected subjects receiving zidovudine (AZT) was determined. After acid treatment, the sensitivity of p24 antigen detection increased fivefold. The proportion of subjects who were antigenemic increased over the 48-week follow-up in the placebo group; approximately 50% of subjects who were p24 antigen-positive at entry and who received AZT showed clearance or a greater than 50% reduction in baseline p24 antigen levels at 16 and 32 weeks. Thus, acid treatment of plasma may allow the use of p24 antigen as a marker of disease progression and therapeutic response.

Objectives: To evaluate the clinical utility of a human immunodeficiency virus (HIV)-IgA serological assay for diagnosis of perinatally acquired HIV infection., Design: Coded serum samples prospectively collected from children born to HIV-infected mothers and uninfected mothers were analyzed by HIV-IgA immunoblot., Setting: A university hospital in Baltimore, Md, and an outpatient clinic in Port-au-Prince, Haiti., Population: Five hundred thirty-nine serum samples were obtained sequentially from 278 children born to HIV-infected women (116 from The Johns Hopkins Hospital and 62 from Port-au-Prince) and from 42 control children born to HIV-seronegative children in Port-au-Prince., Outcome Measures: Results from the HIV-IgA serological assays were compared with the known infection status of the child at 15 months of age as determined by the standard IgG Western blot and the clinical classification of the Centers for Disease Control. Sensitivity, specificity, and predictive values were calculated at different ages and collectively for children 3 months of age or older., Results: The HIV-IgA assay was positive in one of six specimens from HIV-infected children under 1 month of age, six of nine specimens from infected children at 3 months of age, and 160 of 161 specimens from 47 HIV-infected children 6 months of age or older. Of 334 specimens from 243 uninfected children, 333 were negative by the HIV-IgA assay. The overall sensitivity and the specificity of the IgA assay for children older than 3 months of age were 97.6% and 99.7%, and the positive and negative predictive values were 99.4% and 98.7%, respectively., Conclusion: Although the HIV-IgA assay had a low sensitivity within the first months of life, the high sensitivity, specificity, and predictive values of this assay demonstrate its utility for the diagnosis of perinatally acquired HIV infection after the third month of age. Early diagnosis with this relatively simple and inexpensive serological assay should aid in the implementation of antiviral therapy and provide useful information for the care of children born to HIV-infected mothers in both developing and developed countries.

The pressure-natriuresis relationship was studied in anesthetized, 7- to 9-week-old control spontaneously hypertensive rats (SHR) and in SHR that had been treated with hydralazine (20 mg.kg-1.day-1 in drinking water) starting at 4-5 weeks of age. To minimize reflex changes in kidney function during changes in renal artery pressure, neural and hormonal influences on the kidney were fixed by surgical renal denervation, adrenalectomy, and infusion of a hormone cocktail (330 microL.kg-1.mikn-1) containing high levels of aldosterone, arginine vasopressin, hydrocortisone, and norepinephrine dissolved in 0.9% NaCl containing 1% albumin. Changes in renal function were measured using standard clearance techniques, while renal artery pressure was varied between 136 +/- 1 and 186 +/- 2 mmHg (1 mmHg = 133.32 Pa) in control SHR (n = 10) and between 113 +/- 1 and 162 +/- 2 mmHg in treated SHR (n = 11). Mean arterial pressure (+/- SE) under Inactin anesthesia was 172 +/- 3 mmHg in control SHR and 146 +/- 3 mmHg in treated SHR (p less than 0.05). Where renal artery pressure overlapped between groups, there were no significant differences in glomerular filtration rate. Renal blood flow was also similar in both groups, although at 160 mmHg blood flow was slightly but significantly reduced in treated SHR. Urine flow and total and fractional sodium excretion increased similarly with increases in renal artery pressure in both groups, but the pressure-natriuresis curve in hydralazine-treated SHR was displaced to the left along the pressure axis. The data indicate that chronic administration of hydralazine in young SHR enhances fractional sodium excretion, suggesting that tubular reabsorption of sodium is decreased by hydralazine.

To evaluate the sensitivity and specificity of HTLV-I/II assays, serum from 1100 pregnant Haitian women was tested with seven commercially available HTLV I/II assays. Serum that was found to be reactive in any assay was analysed by western blot and all indeterminate samples were further characterised by radioimmunoprecipitation assays (RIPA). 59 (5.4%) samples were HTLV I/II antibody positive by western blot and/or RIPA. The sensitivity of these seven assays ranged from 93.2% to 100%. with the 'Recombinant HTLV-I' (Cambridge Bioscience) and 'Serodia HTLV-I' (Fujirebio) assays having the highest sensitivity (100%). The specificity of these assays ranged from 98.4% to 100%, with the Abbott assay having the highest specificity (99.5%, 100%) according to two different methods of evaluation. Whether the antigens used in any assay were whole disrupted virus or recombinant gene products made no difference. The low positive predictive values of some of these assays (71.8-91.7%), even in a high prevalence population, and the need for RIPA to test indeterminate sera, indicate that for routine screening of blood donors there is still room for improvement both in screening and confirmatory assays for HTLV-I/II.

The effect of chronic angiotensin I converting enzyme inhibition on the pressure-natriuresis relation was studied in Wistar-Kyoto and spontaneously hypertensive rats. Enalapril maleate (25 mg.kg-1.day-1 in drinking water) was started at 4-5 weeks of age. At 7-9 weeks of age, the pressure-natriuresis relation was studied while the rats were under Inactin anesthesia 1 week after the right kidney and adrenal gland were removed. Neural and hormonal influences on the remaining kidney were fixed by surgical renal denervation, adrenalectomy, and infusion of a hormone cocktail (330 microliters.kg-1.min-1) containing high levels of aldosterone, arginine vasopressin, hydrocortisone, and norepinephrine dissolved in 0.9% NaCl containing 1% albumin. Changes in renal function resulting from alterations in renal artery pressure were compared between enalapril-treated and control rats. Mean arterial pressure (+/- SEM) under anesthesia was 118 +/- 5, 94 +/- 4, 175 +/- 3, and 124 +/- 2 mm Hg for control Wistar-Kyoto (n = 10), enalapril-treated Wistar-Kyoto (n = 10), control spontaneously hypertensive (n = 9), and enalapril-treated spontaneously hypertensive (n = 9) rats, respectively. When renal artery pressure was set at values above approximately 125 mm Hg, control spontaneously hypertensive rats excreted less sodium and water than control Wistar-Kyoto rats. Enalapril treatment resulted in a significant and similar shift to the left of the pressure-natriuresis relation in both strains of rats so that a lower renal artery pressure was required to excrete a similar amount of sodium when compared with their respective untreated controls.(ABSTRACT TRUNCATED AT 250 WORDS)

To determine whether enhanced sympathetic tone contributes to the maintenance of chronic angiotensin II (A II, 10 ng/min i.v. for 10 days) hypertension in rats, sympathetic activity was assessed in hypertensive and control rats by measuring norepinephrine (NE) turnover (alpha-methyl-p-tyrosine) in peripheral organs and by measuring depressor responses to ganglionic blockade in conscious rats. Pressor responses to methoxamine (1-8 micrograms/min) and arginine vasopressin (0.5-4 ng/min) were also obtained in rats with ganglionic blockade. Chronic A II infusion produced significant hypertension (mean +/- S.E. tail cuff pressure: 176 +/- 5 vs. 134 +/- 2 mm Hg in controls; n = 23 each group) but there were no significant differences in NE turnover in heart, kidney, skeletal muscle, or intestine in hypertensive rats compared with controls. Ganglionic blockade produced a significantly larger decrease in mean arterial pressure in A II-treated rats when compared with controls (73 +/- 7 vs. 38 +/- 2 mm Hg, n = 18 for each group). Dose-response curves for methoxamine and vasopressin were not significantly different between groups. The results suggest that the maintenance of chronic A II hypertension does not involve postsynaptic interactions between A II and the sympathetic system. The NE turnover data do not support the hypothesis that rats with chronic A II hypertension have enhanced sympathetic tone.

To determine the contribution of renal nerves to natriuresis produced by selective alpha-2 adrenergic receptor activation in volume-loaded. Inactin-anesthetized rats, responses to B-HT 933 (20 micrograms/kg/min, i.v.) were compared in the chronically denervated kidney with responses in the contralateral innervated kidney. Plasma vasopressin concentration was maintained at high physiological levels by constant infusion of arginine vasopressin (170 pg/kg/min, i.v.). Control rats received arginine vasopressin and saline only. Arterial pressure and heart rate were decreased significantly by B-HT 933 (12 mm Hg and 80 beats/min. respectively). Glomerular filtration rate was not altered in innervated or denervated kidneys, whereas renal blood flow was decreased slightly, but significantly, in denervated but not innervated kidneys. B-HT 933 increased urine flow and total and fractional sodium excretion significantly in innervated kidneys but not in denervated kidneys when compared with control animals. Urine osmolality was also decreased significantly in innervated kidneys, but remained hyperosmotic to plasma. The data indicate that, in the presence of fixed levels of arginine vasopressin, chronic renal denervation prevented the natriuretic and diuretic effect of B-HT 933 in anesthetized rats. These results suggest that central and/or peripheral effects of alpha-2 adrenergic receptor activation were involved in producing natriuresis in the innervated kidney by decreasing renal sympathetic nerve influence on tubular sodium reabsorption.

The role of the renal nerves in the electrolyte excretion of rats fed or fasted overnight was determined in conscious rats and anesthetized (Inactin) and surgically prepared rats. In conscious rats sodium excretion, as measured in a 1-h urine collection period after feeding or fasting overnight, was decreased with fasting with or without renal nerves. Renal nerve activity, as measured by norepinephrine turnover (inhibition of tyrosine hydroxylase by alpha-methyl-p-tyrosine), was not different between conscious fed or fasted rats and increased to the same extent in fed and fasted rats when anesthetized and surgically prepared. Anesthetized, surgically prepared rats infused with 5.0% glucose showed a denervation natriuresis if rats were fed overnight, but not if they had been fasted overnight. Potassium excretion in conscious and anesthetized rats was lower in fasted rats than fed rats with or without renal nerves. These data suggest (i) renal nerves are not involved in the renal response to an overnight fast in conscious rats, and (ii) in anesthetized, surgically prepared rat renal sympathetic tone is enhanced and denervation natriuresis occurs if rats are fed but not if fasted. Potassium excretion is a reflection of whether rats are fed or fasted and not whether they have renal nerves.

Male Wistar rats chronically fed a low level (0.41%) of linoleic acid (LA) in the diet as supplied by 5% olive oil developed a significant elevation of systolic blood pressure as compared with rats fed either a medium (4.2%) or high (9.4%) level of dietary LA. Chronic excess intake of NaCl (3.75% in the diet) was associated with a significant elevation of blood pressure on all three diets but a low level of LA in the diet exaggerated the salt-induced hypertension. The results suggest that inadequate dietary LA may result in an increase in systolic blood pressure regardless of the sodium content of the diet.

We have used a model for measuring renal clearances in the undisturbed rat to assess the role of the renal nerves in the depression of renal function during sodium pentobarbital anesthesia. One group of rats was studied with renal nerves intact and a second group was studied 7-9 days after bilateral renal denervation. Rats were prepared by placement of cannulae an average of 5 days prior to the clearance experiments. Renal function was measured before and after the injection of saline as the control vehicle and 2-3 days later, before, and after the injection of sodium pentobarbital (50 mg/kg) in the same rat. Sodium pentobarbital produced comparable decreases in glomerular filtration rate, para-aminohippuric acid clearance, urine flow rate, and sodium excretion in rats with denervated or innervated kidneys. Injection of saline resulted in no differences in measured variables between the rats with intact or sectioned renal nerves. Sodium pentobarbital caused a drop in arterial pressure in the denervated group but not in the innervated group. In a second series of experiments rats with denervated kidneys were implanted with an inflatable occluder around the aorta. This occluder was inflated to limit the drop in arterial pressure during anesthesia. When the blood pressure to the kidneys was maintained, renal function did not decrease during sodium pentobarbital anesthesia. These experiments suggest that the renal nerves are involved in the decrease in renal function during sodium pentobarbital anesthesia.

Vasopressin (AVP) in acute experiments has been shown to influence cardiovascular reflexes, but the effect of a more prolonged administration of AVP on the sympathetic nervous system has not been investigated. Long-Evans rats were treated for 7 days with AVP (Pitressin tannate in oil, with single daily doses of 100 or 500 mU.100 g-1, s.c.) to determine whether AVP alters norepinephrine (NE) turnover in kidney, intestine, or skeletal muscle. Control rats were given equal doses of peanut oil daily. NE turnover was determined by measuring the decline in tissue levels of NE for 8 h after inhibition of tyrosine hydroxylase with alpha-methyl-p-tyrosine (300 mg.kg-1, i.p. every 4 h). Measurements of water intake, urine output, and urine osmolality showed that chronic administration of the high dose, but not the low dose, of AVP produced maintained increases in urine osmolality and decreases in water intake and urine output. Body weight, plasma osmolality, plasma electrolytes, and hematocrit were not significantly altered by AVP treatment, but mean arterial pressure was elevated significantly (control, 105 +/- 3 mmHg versus AVP, 119 +/- 4 mmHg, p less than 0.05) (1 mmHg = 133.3 Pa) in the high dose group. Plasma renin activity was decreased slightly, but significantly in rats treated with the high dose of AVP. Compared with results in control animals, there were no statistically significant changes in NE turnover after chronic administration of either the low or the high dose of AVP. The results indicate that administration of AVP for 7 days to rats in normal fluid balance does not result in a decrease in NE turnover in peripheral organs.

Previous studies of noradrenergic mechanisms in spontaneously hypertensive rats (SHR) have yielded conflicting results, as many have used: 1) rats of only one age; 2) a single organ such as heart or brain; or 3) either Wistar-Kyoto (WKY) or an outbred normotensive control rat. We have studied the turnover of norepinephrine (NE) in three brain areas (cortex, hypothalamus, brain stem) and three peripheral organs (duodenum, skeletal muscle, kidney) of SHR, WKY, and Wistar rats at 5, 9, and 18 weeks of age. The rate of decline of norepinephrine [NE] in tissue was determined with a fluorescence assay at 0, 2, 4, and 8 hours after inhibition of tyrosine hydroxylase with alpha-methyltyrosine. Differences in NE turnover were inferred by comparing slopes of regression lines calculated for the plot of log [NE] (expressed as a percent of the initial concentration) vs time. Systolic arterial pressure of SHR was similar to that of WKY and Wistar rats at 5 weeks of age, but increased to 150 mm Hg by 9 weeks and reached an average of 190 mm Hg by 18 weeks. The turnover of NE in 5-week-old SHR compared to two normotensive strains was significantly lower in the cortex and significantly higher in the kidney and skeletal muscle. By 9 weeks, in SHR, NE turnover had increased significantly in the hypothalamus and brain stem, while decreasing significantly in the kidney and duodenum. No such changes were seen in these organs of WKY or Wistar rats when comparing turnover of NE at 5 and 9 weeks. At 18 weeks, there were no further differences in the organs of SHR when compared to values obtained at 9 weeks. These data support the hypothesis that the turnover of NE may be altered in central and peripheral organs of young SHR, and may initiate or contribute to the development of hypertension. Changes in turnover of NE in the brain and peripheral organs between 5 and 9 weeks in SHR suggest compensatory responses to increasing arterial pressure; however, similar changes in turnover were not seen between 9 and 18 weeks, although arterial pressure continued to increase.

During skeletal myogenesis, approximately 20 contractile proteins and related gene products temporally accumulate as the cells fuse to form multinucleated muscle fibers. In most instances, the contractile protein genes are regulated transcriptionally, which suggests that a common molecular mechanism may coordinate the expression of this diverse and evolutionarily unrelated gene set. Recent studies have examined the muscle-specific cis-acting elements associated with numerous contractile protein genes. All of the identified regulatory elements are positioned in the 5'-flanking regions, usually within 1,500 base pairs of the transcription start site. Surprisingly, a DNA consensus sequence that is common to each contractile protein gene has not been identified. In contrast to the results of these earlier studies, we have found that the 5'-flanking region of the quail troponin I (TnI) gene is not sufficient to permit the normal myofiber transcriptional activation of the gene. Instead, the TnI gene utilizes a unique internal regulatory element that is responsible for the correct myofiber-specific expression pattern associated with the TnI gene. This is the first example in which a contractile protein gene has been shown to rely primarily on an internal regulatory element to elicit transcriptional activation during myogenesis. The diversity of regulatory elements associated with the contractile protein genes suggests that the temporal expression of the genes may involve individual cis-trans regulatory components specific for each gene.