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Alzheimer's disease (AD) and osteoporosis (OP) pose distinct but interconnected health challenges, both significantly impacting the aging population. AD, a neurodegenerative disorder characterized by memory impairment and cognitive decline, is primarily associated with the accumulation of abnormally folded amyloid beta (Aβ) peptides and neurofibrillary tangles in the brain. OP, a skeletal disorder marked by low bone mineral density, involves dysregulation of bone remodeling and is associated with an increased risk of fractures. Recent studies have revealed an intriguing link between AD and OP, highlighting shared pathological features indicative of common regulatory pathophysiological pathways. In this article, we elucidate the signaling mechanisms that regulate the pathology of AD and OP and offer insights into the intricate network of factors contributing to these conditions. We also examine the role of bone-derived factors in the progression of AD, underscoring the plausibility of bidirectional communication between the brain and the skeletal system. The presence of amyloid plaques in the brain of individuals with AD is akin to the accumulation of brain Aβ in vascular dementia, pointing towards the need for further investigation of shared molecular mechanisms. Moreover, we discuss the role of bone-derived microRNAs that may regulate the pathological progression of AD, providing a novel perspective on the role of skeletal factors in neurodegenerative diseases. The insights presented here should help researchers engaged in exploring innovative therapeutic approaches targeting both neurodegenerative and skeletal disorders in aging populations., Competing Interests: Declarations. Conflict of interest: The authors declare no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. Further, the authors received no financial support for the research, authorship, and/or publication of this article. Consent to participate: Not applicable. Consent for publication: Authors consent for the publication of the manuscript., (© 2025. The Author(s), under exclusive licence to Springer Nature B.V.)

Changes in the national examination structures have renewed interest in the development of test-taking strategies for professional students in the health sciences. It is often assumed that these high-achieving students have developed proficient test-taking skills and abilities before admittance. However, the assessments in these programs and for national licensure require an elevated level of reasoning and integration with clinical concepts. It was hypothesized that the implementation of an immersive test-taking strategies program would improve dental student perceptions of their abilities. A "toolbox" of four methods was implemented, which included 1 ) an introductory video that provided students with 10 tips for approaching high-level exam questions; 2 ) problem solution videos interspersed with class practice problems to walk students independently through rationales; 3 ) collaborative group assessments in which students implemented the strategies in teams to prepare for exams; and 4 ) unit exam debriefings to review the question rationales. Although all methods were positively reviewed on surveys, students indicated that the problem solution videos and the collaborative group assessments were more helpful and improved their test-taking skills significantly more than the other strategies ( P < 0.01, 1-way ANOVA and Bonferroni post hoc test). Students felt they had developed strong test-taking strategies (average of 4.21 on a 5-point scale, SD 0.76) and felt more prepared for the Integrated National Board Dental Examination (4.48, SD 0.66). These results suggest that a multipronged approach with frequent opportunities to practice test-taking strategies can improve student perceptions of their ability to master high-level and integrated assessment questions. NEW & NOTEWORTHY Professional students in the health sciences may need to improve their test-taking skills for high-level and integrated assessments. A toolbox of strategies was implemented in a Dental Physiology course that included an introductory video, problem solution videos for practice problems, collaborative group assessments, and unit exam debriefings. The students reported that the strategies were helpful, improving their preparation and test-taking strategies for summative exams such as the Integrated National Board Dental Examination.

With the increased attention focused on active learning, educators strive to find better and more innovative ways to engage students in the classroom. One of the hurtles that educators are presented with is that the classroom is no longer limited to a physical location but rather students and professor can meet via the internet, Before COVID-19, distance or remote learning was something that students, by and large, had the option of choosing in which whether to engage. Students had the option to take "online courses," whether those be synchronous remote learning or asynchronous online courses. Indeed, numerous studies have focused on investigating the efficacy of many different approaches to distance and online learning. Unfortunately, COVID 19 mandated a rapid transition to remote learning, and with this forced change has come what some students describe as "Zoom fatigue" (Wolf CR. Psychology Today, May 2020). Many students reported feeling exhausted, overwhelmed, and disengaged by the dramatic increase in mandated distance education required by the COVID pandemic. Video conferencing has become the "go-to" panacea for education during this time, and students are spending unprecedented amounts of time in front of a screen when normally they would be in a classroom. This heretofore singular and unique approach to education coupled with decreased peer-to-peer interaction has caused a problem with student engagement (Goodman BE, Barker MK, Cooke JE. Adv Physiol Educ 42: 417-423, 2018). Students' engagement and performance have decreased during COVID-19 because of forced online learning and lack of peer interaction. We hypothesize that creating a nongraded, fun, and relaxing physiology-focused "Trivia Night" will increase student engagement and performance on summative assessments. Using a master's level class progressing through the respiratory physiology module utilizing remote, synchronous lectures to deliver content, we introduced a voluntary Trivia Night review session with teams randomly assigned to increase interaction among peers and review respiratory physiology material. NEW & NOTEWORTHY This article presents the effectiveness of the use of the "pub Trivia Night" to facilitate learning, deconstruct misconceptions, and increase engagement during remote teaching due to the COVID-19 pandemic.

Male rat renal blood vessels undergo reduced contraction to norepinephrine with aging. There is a greater renal vascular impairment in male compared with female rats. We investigated specific tyrosine kinase receptor inhibition of renal interlobar artery responsiveness to phenylephrine in male and female rats at specifically designated ages. Vessels from young male rats contracted much less to phenylephrine when the vessels were pretreated with the tyrosine kinase inhibitors Lavendustin A, HNMPA-(AM)₃, or AG1478. Vessels from adult female rats pretreated with Lavendustin A showed no difference in contraction from control, but did demonstrate a slightly reduced contraction when pretreated with AG1478. Middle-aged male rat vessels treated with Lavendustin A demonstrated no inhibition, but the insulin and epidermal growth factor receptor (EGFR) antagonists both induced a decline in contraction. Vessels from aged male rats demonstrated no effect related to the 3 pretreatments. Middle-aged and aged female rats pretreated with any inhibitor demonstrated no inhibitor-dependent alterations. We conclude that maximum contraction of interlobar arteries from adult male rats is reduced when tyrosine kinase receptor activity is reduced. Female rats demonstrated much less inhibitor-related change of contraction.

Remodeling by its very nature implies synthesis and degradation of extracellular matrix components (such as elastin, collagen, and connexins). Most of the vascular matrix metalloproteinase (MMP) are latent because of the presence of constitutive nitric oxide (NO). However, during oxidative stress peroxinitrite (ONOO-) activates the latent MMPs and instigates vascular remodeling. Interestingly, in mesenteric artery, homocysteine (Hcy) decreases the NO bio-availability, and folic acid (FA, an Hcy-lowering agent) mitigates the Hcy-mediated mesentery artery dysfunction. Dimethylarginine dimethylaminohydrolase-2 (DDAH-2) and endothelial nitric oxide synthase (eNOS) increases NO production. The hypothesis was that the Hcy decreased NO bio-availability, in part, activating MMP, decreasing elastin, DDAH-2, eNOS and increased vasomotor response by increasing connexin. To test this hypothesis,the authors used 12-week-old C57BJ/L6 wild type (WT) and hyperhomocysteinemic (HHcy)-cystathione beta synthase heterozygote knockout (CBS+/-) mice. Blood pressure measurements were made by radio-telemetry. WT and MMP-9 knockout mice were administered with Hcy (0.67 mg/ml in drinking water). Superior mesenteric artery and mesenteric arcade were analyzed with light and confocal microscopy. The protein expressions were measured by western blot analysis. The mRNA levels for MMP-9 were measured by RT-PCR. The data showed decreased DDAH-2 and eNOS expressions in mesentery in CBS-/+ mice compared with WT mice. Immuno-fluorescence and western blot results suggest increased MMP-9 and connexin-40 expression in mesenteric arcades of CBS-/+ mice compared with WT mice. The wall thickness of third-order mesenteric artery was increased in CBS-/+ mice compared to WT mice. Hcy treatment increased blood pressure in WT mice. Interestingly, in MMP-9 KO, Hcy did not increase blood pressure. These results may suggest that HHcy causes mesenteric artery remodeling and narrowing by activating MMP-9 and decreasing DDAH-2 and eNOS expressions, compromising the blood flow, instigating hypertension, and acute abdomen pain.

Our hypothesis is that impairment of peroxisome proliferator-activated receptor-gamma (PPARgamma) initiates renal dysfunction by increasing renal glomerular matrix metalloproteinase-2 (MMP-2) activity because of increased renal homocysteine (Hcy) and decreased nitric oxide (NO) levels. C57BL/6J mice were made diabetic (D) by being fed a high-fat-calorie diet, and an increase in PPARgamma activity was induced by adding pioglitazone (Pi) to the diet. Mice were grouped as follows: normal calorie diet (N), D, N+Pi, and D+Pi (n = 6/group). The glomerular filtration rate (GFR), renal artery blood flow and pressure, and plasma glucose were measured. Renal glomeruli and preglomerular arterioles were isolated. Plasma and glomerular levels of NO, Hcy, and MMP activity were measured. The contractile response to phenylephrine and the dilatation response to acetylcholine in renal arteriolar rings were measured in a tissue myobath. In N, D, N+Pi, and D+Pi groups, respectively, GFR was 9.4 +/- 1.2, 3.9 +/- 1.1, 9.2 +/- 1.6, and 8.4 +/- 1.4 microl x min(-1) x g body wt(-1). Renovascular resistance was 140 +/- 3, 367 +/- 21, 161 +/- 9, and 153 +/- 10 mmHg x ml x min(-1). Levels of Hcy were increased from 5.8 +/- 1.5 in the N to 18.0 +/- 4.0 micromol/l in the D group. Glomerular levels of MMP-2 were increased in D mice compared with N mice, and there was no change in levels of MMP-9. Treatment with Pi ameliorated glomerular levels of MMP-2 and Hcy in the D group. Renal artery ring contraction and relaxation by phenylephrine and acetylcholine, respectively, were attenuated in the D groups compared with the N groups. Results suggest that a PPARgamma agonist ameliorates preglomerular arteriole remodeling in diabetes by decreasing tissue levels of Hcy and MMP-2 activity and increasing NO.

The agonists of peroxisome proliferator-activated receptor-gamma (PPARgamma) ameliorate cardiovascular complications associated with diabetes mellitus. We tested the hypothesis that recovery from ailing to failing myocardium in diabetes by PPARgamma agonist is in part due to decreased matrix metalloproteinase-9 (MMP-9) activation and left ventricular (LV) tissue levels of homocysteine (Hcy). C57BL/6J mice were made diabetic (D) by feeding them a high-fat calorie diet. PPARgamma was activated by adding pioglitazone (Pi) to the diet. After 6 wk, mice were grouped into: normal calorie diet (N), D, N + Pi and D + Pi (n = 6 in each group). LV variables were measured by echocardiography, endothelial-myocyte (E-M) coupling was measured in cardiac rings, and MMP-9 activation was measured by zymography. Blood glucose levels were twofold higher in D mice compared with N mice. Pi decreased the levels of glucose in D mice to the levels in N mice. LV Hcy levels were 3.5 +/- 0.5 microM in N groups compared with 12.4 +/- 0.6 microM in D groups. Treatment with Pi normalized the LV levels of Hcy but had no effect on plasma levels of Hcy. In the D group, LV contraction was reduced compared with that of the N group and was ameliorated by treatment with Pi. LV wall thickness was reduced to 0.25 +/- 0.02 mm in the D group compared with 0.42 +/- 0.01 mm in the N group. LV diastolic diameter was 3.05 +/- 0.01 mm in the D group compared with 2.20 +/- 0.02 mm in the N group. LV systolic diameter was 1.19 +/- 0.02 mm in the D group and 0.59 +/- 0.01 mm in the N group. Pi normalized the LV variables in D mice. The responses to ACh and nitroprusside were attenuated in diabetic hearts, suggesting that there was E-M uncoupling in the D group compared with the N group, which was ameliorated by Pi. Plasma and LV levels of MMP-2 and -9 activities were higher in the D group than in the N group but normalized after Pi treatment. These results suggest that E-M uncoupling in the myocardium, in part, is due to increased MMP activities secondary to suppressing PPARgamma activity in high-fat, calorie-induced Type 2 diabetes mellitus.

Complications associated with insulin-dependent diabetes mellitus (type-1diabetes) primarily represent vascular dysfunction that has its origin in the endothelium. While many of the vascular changes are more accountable in the late stages of type-1diabetes, changes that occur in the early or initial functional stages of this disease may precipitate these later complications. The early stages of type-1diabetes are characterized by a diminished production of both insulin and C-peptide with a significant hyperglycemia. During the last decade numerous speculations and theories have been developed to try to explain the mechanisms responsible for the selective changes in vascular reactivity and/or tone and the vascular permeability changes that characterize the development of type-1diabetes. Much of this research has suggested that hyperglycemia and/or the lack of insulin may mediate the observed functional changes in both endothelial cells and vascular smooth muscle. Recent studies suggest several possible mechanisms that might be involved in the observed decreases in vascular nitric oxide (NO) availability with the development of type-1 diabetes. In addition more recent studies have indicated a direct role for both endogenous insulin and C-peptide in the amelioration of the observed endothelial dysfunction. These results suggest a synergistic action between insulin and C-peptide that facilitates increase NO availability and may suggest new clinical treatment modalities for type-1 diabetes mellitus., (Copyright 2005 Wiley-Liss, Inc.)

As human males age, a decline in baroreflex-mediated elevation of blood pressure occurs due, at least in part, to a reduction in alpha-1 adrenergic vasoconstrictor function. Alpha adrenergic constriction is mediated by guanosine triphosphate binding Protein (G Protein) coupled signaling pathways. Alpha-1 A/C, B, and D adrenergic receptor expressions, measured by GeneChip array, are not reduced during aging in renal blood vessels of male or female rats. Alpha-1 A GeneChip expression is greater, at all ages studied, in females than in males. Prazosin binding by alpha-1 adrenergic receptors is greater in young adult female rats than in young adult male rats; however, it is reduced with aging in both male and female rats. G alpha q GeneChip expression declines while expression of adrenergic receptor kinase (GRK2) and tyrosine phosphatases (TyrP) increase with aging in male rats. The declines in alpha-1 adrenergic receptor binding and G alpha q expression and also the increases in GRK2 and TyrP expression likely relate to the age-related decline of vasoconstriction in male rats. The information that the expression of alpha-1 A adrenergic receptors is greater in female rats and (GRK2) expression does not increase during aging could relate to the gender differences in vasoconstrictor function with aging. Gene therapy to ameliorate the age-related decline in renal function could possibly reduce the need for renal dialysis. Signaling pathways such as those reviewed herein may provide an outline of the molecular pathways needed to move toward successful renal gene therapy for aging individuals., (Copyright 2005 Wiley-Liss, Inc.)

This study was designed to test the hypothesis that endogenous estrogens decrease the expression of endothelial nitric oxide synthase (eNOS) in resistance-size bone arterioles, thereby reducing endothelium-dependent vasodilator function. Sexually mature female rats were ovariectomized to reduce endogenous estrogens. Age-matched female rats served as controls. Seven to ten days after ovariectomy, bone marrow tissue was collected from the femoral canal. Immuno-histochemistry was performed to detect expression of estrogen receptors, alpha and beta and eNOS. eNOS protein content in medullary bone arterioles was compared using Western blot analysis. Endothelial cell function was assessed by quantitating the dilation of isolated, pressurized bone arterioles in response to acetylcholine. The results indicate that the endothelium of bone arterioles from ovariectomized and control rats express ER-alpha, ER-beta and eNOS. eNOS protein content in the two groups of arterioles did not differ. However, the baseline diameter of arterioles from ovariectomized rats (63+/-4 microm) was significantly smaller than the diameter of arterioles from control rats (75+/-3 microm, p<0.05). The two groups of arterioles dilated equally in response to acetylcholine. L-NAME, an inhibitor of eNOS, almost completely abolished the dilator responses to acetylcholine, but not to sodium nitroprusside. L-Arginine restored acetylcholine-induced dilation after L-NAME treatment. Thus, arteriole dilation to acetylcholine appears to be mediated almost exclusively by NO. The smaller diameter of arterioles from ovariectomized rats suggests that endogenous estrogens exert a significant dilator influence on bone arterioles. However, the dilator influence does not appear to be mediated by an increase in eNOS expression or enhanced NO-dependent vasodilation. These results indicate that estrogens do not decrease eNOS expression or diminish NO-mediated dilation of bone medullary arterioles.

Age and/or gender appear to moderate alpha-adrenergic mediated constrictor mechanisms found in the interlobar arteries of the Munich Wistar rat. We have determined the extent of constriction to alpha-adrenergic receptor stimulation using norepinephrine, phenylephrine and A61603 (α1A-adrenergic receptor agonist) as a function of age and gender. Norepinephrine produced less constriction in male-derived arteries at ages greater than eight months as compared to the younger adult male (four to six months). The arteries derived from females did not demonstrate altered constriction until greater than 15 months of age. Similarly, arteries derived from the male demonstrated weaker constrictions to phenylephrine (10(-6) to 10(-3) M) at ages greater than eight months while arteries from females showed differences at greater than 15 months. In contrast, the effective concentration of norepinephrine to cause a 50% maximal constriction (EC50) was significantly less in the four to five-month-old male rats compared to the pooled data from older groups. Interestingly, four to five month old males had A61603 EC50 values similar to the 8 to 12-month and 15+ old females. These studies conclude that an age related loss of sympathetic α-adrenergic constriction of renal interlobar arteries is present in Munich Wistar rats. Furthermore, this loss, while similar along longitudinal aspects of age, is also different as a function of gender with the loss of α-adrenergic constrictor function delayed in the female when compared to the male.

Aging humans and rats have a reduced renal vascular constriction response to stress, change in posture, or exercise. In this study, renal interlobar arteries from 9- (intermediate age) to 15-month-old (aging) male Wistar rats constricted less to alpha-adrenergic agonists than those of 4-month-old (young adult) rats. The reduced contraction to A61603 (alpha 1 A agonist) was similar to that to norepinephrine and phenylephrine. Therefore, it appears that the reduction in constriction is primarily related to alpha 1 A receptor stimulation. GeneChip microarray hybridization analysis of the interlobar arteries with the RAE 230A GeneChip indicated that there were no significant differences in gene expression for alpha 1 A/C, 1B, or 1D receptors between 4-month-old (young adult) and 1-year-old (aging) male Wistar rats. Competitive binding experiments (prazosin) revealed that maximal binding (Bmax, fmol/mg protein) of the alpha 1 receptors of interlobar arteries was reduced 25% by 10 months of age and 50% by 18+ months of age. Alpha 1 receptor-induced arterial constriction and prazosin binding were both down-regulated. The loss of receptor-initiated constriction likely includes down-regulation of maximum agonist binding by alpha 1 adrenergic receptors.

Accumulation of oxidized-matrix (fibrosis) between the endothelium (the endothelial cells embedded among the myocytes) and cardiomyocytes is a hallmark of diabetes mellitus and causes diastolic impairment. In diabetes mellitus, elevated levels of homocysteine activate matrix metalloproteinase and disconnect the endothelium from myocytes. Extracellular matrix functionally links the endothelium to the cardiomyocyte and is important for their synchronization. However, in diabetes mellitus, a disconnection is caused by activated metalloproteinase, with subsequent accumulation of oxidized matrix between the endothelium and myocyte. This contributes to endothelial-myocyte uncoupling and leads to impaired diastolic relaxation of the heart in diabetes mellitus. Elevated levels of homocysteine in diabetes are attributed to impaired homocysteine metabolism by glucose and insulin and decreased renal clearance. Homocysteine induces oxidative stress and is inversely related to the expression of peroxisome proliferators activated receptor (PPAR). Several lines of evidence suggest that ablation of the matrix metalloproteinase (MMP-9) gene ameliorates the endothelial-myocyte uncoupling in diabetes mellitus. Homocysteine competes for, and decreases the PPARgammaactivity. In diabetes mellitus, endothelial-myocyte uncoupling is associated with matrix metalloproteinase activation and decreased PPARgamma activity. The purpose of this review is to discuss the role of endothelial-myocyte uncoupling in diabetes mellitus and increased levels of homocysteine, causing activation of latent metalloproteinases, decreased levels of thioredoxin and peroxiredoxin, and cardiac tissue inhibitor of metalloproteinase (CIMP) in response to antagonizing PPARgamma.

Elevated fibrinogen (Fg) concentration in blood is a high risk factor for many cardiovascular diseases. We hypothesize that Fg and its early degradation product, fragment D, may result in arterial constriction by binding endothelial intercellular adhesion molecule-1 (ICAM-1). The vasoconstriction induced by Fg and fragment D was studied in third- and second-order arterioles (3As and 2As, respectively) of Sprague-Dawley rat cremaster muscle in vivo, in aortic and femoral artery rings, and in the segments of first-order arterioles (1As) isolated from rat cremaster muscle. Intravascular infusion of Fg induced significant constriction of 3As and 2As (by 33.4 +/- 3.4 and 23.7 +/- 4.3%, respectively) in vivo and was abolished in the presence of the specific endothelin type A receptor blocker BQ-610. Fg and fragment D produced significant constriction of both aortic and femoral artery rings. Isolated 1As constricted in response to Fg (0.3 microM) and fragment D (3 microM) by 31 +/- 1.4 and 12 +/- 1.5%, respectively. Fluorescently labeled Fg and fragment D bound to the vascular wall, whereas albumin bound to a significantly lesser degree. The binding of Fg and fragment D to the arteriolar wall and constriction of aortic and femoral artery rings as well as isolated 1As were abolished in the presence of anti-Fg and anti-ICAM-1 antibodies. These results indicate that binding of Fg and fragment D to the vascular wall through ICAM-1 may contribute to the increased vascular tone and resistance that compromise circulation.

Renal nephropathy present in male Wistar rats more than 13 months of age was reported as an indication that the rats were in renal failure. In this study, the renal tissue damage at 14 months of age in male Munich Wistar rats was similar to that reported for Wistar rats, indicating that Munich Wistar rats could be another model for study of kidney function in the aging rat. The usual renal response to injury involves increased cell division and/or reparative processes that involve tyrosine kinase activity (TyrK) and/or guanosine triphosphate-binding (G) protein signal trans-duction pathways. This study reveals the presence of renal tissue damage coinciding with significantly reduced activity of Ras, Akt, and p34cdc2 kinase, the signaling proteins that regulate cell division and/or growth, in renal cortical tissues of aging rats compared to young rats (P < 0.005, P < 0.005, and P< 0.001, respectively). These results suggest that proteins involved in signal transduction pathways associated with cell replication are downregulated in the aging kidney cortex at a time when renal cellular damage is also present.

Dietary copper is an essential trace element with roles in both functional and structural aspects of the cardiovascular system. In particular, the vascular response to inflammatory stimuli is known to be significantly augmented in copper-deficient rats. The current study was designed to quantify the extent of injury-induced neointimal proliferation and stenosis in rats fed diets either adequate or deficient in copper. Male, weanling Sprague-Dawley rats were fed purified diets that were either adequate (CuA; 5.6 microg Cu/g) or deficient (CuD; 0.3 microg Cu/g) in copper for 4 weeks. Balloon injury was induced in the left external carotid arteries. Fourteen days after injury, histomorphometric analysis of cross-sections from carotid arteries showed increased neointimal formation in the CuD group compared with the CuA controls (neointima/media ratio: 4.55 +/- 0.93 vs 1.45 +/- 0.2, respectively). These results correspond with data indicating that the activity of Cu/Zn-superoxide dismutase (SOD) is depressed in rats fed this CuD diet. Because superoxide anion and redox status are known to play a key role in the extent of neointimal formation in response to injury, we propose that the exaggerated neointimal proliferation seen in the CuD group is the result of the diminished Cu/Zn-SOD activity.

We examined endothelial modulation of norepinephrine (NE)-mediated constriction in isolated, cannulated, first-order arterioles from skeletal muscle of rats. Acute arteriolar constrictor responses to NE (10(-9) to 10(-7) M) were significantly (P < 0.05) enhanced after either endothelial denudation or inhibition of nitric oxide synthase with NG-monomethyl-L-arginine (10(-4) M, 30 min). In contrast, arteriolar constrictions to NE were not different after treatment with either the cyclooxygenase inhibitor diclofenac (10(-6) M, 30 min) or the K+-channel blocker tetrabutylammonium (5 x 10(-5) M, 30 min). We also measured arteriolar responses to the vasoconstrictor PGF2alpha; responses were not altered by any of the experimental treatments, which indicates that this phenomenon is not ubiquitous to all vasoconstricting agents. Mechanistically, we examined vascular smooth muscle (VSM) and endothelial cell calcium. Both NE and PGF2alpha significantly increased VSM cell calcium measurements; however, endothelial cell calcium was significantly increased with NE or phenylephrine (an alpha1-adrenergic agonist) but not with PGF2alpha or UK-14304 (an alpha2-adrenergic agonist). Together these findings suggest that in rat cremaster first-order arterioles, NE stimulates an increase in VSM calcium via adrenergic receptors with subsequent increase in endothelial cell calcium, possibly via stimulation of alpha1-adrenergic receptors on the arteriolar endothelium. The burst in endothelial cell calcium may then lead to the production of nitric oxide, which diffuses to the VSM, attenuates constriction, and maintains at least some minimal level of blood flow.

Recently, a vagally mediated excitatory lung reflex (ELR) causing neural hyperpnea and tachypnea was identified. Because ventilation is regulated through both inspiratory and expiratory processes, we investigated the effects of the ELR on these two processes simultaneously. In anesthetized, open-chest, and artificially ventilated rabbits, we recorded phrenic nerve activity and abdominal muscle activity to assess the breathing pattern when the ELR was evoked by directly injecting hypertonic saline (8.1%, 0.1 ml) into lung parenchyma. Activation of the ELR stimulated inspiratory activity, which was exhibited by increasing amplitude, burst rate, and duty cycle of the phrenic activity (by 22 +/- 4, 33 +/- 9, and 57 +/- 11%, respectively; n = 13; P < 0.001), but suppressed expiratory muscle activity. The expiratory muscle became silent in most cases. On average, the amplitude of expiratory muscle activity decreased by 88 +/- 5% (P < 0.002). The suppression reached the peak at 6.9 +/- 1 s and lasted for 200 s (median). Injection of H(2)O(2) into the lung parenchyma produced similar responses. By suppressing expiration, the ELR produces a shift in the workload from expiratory muscle to inspiratory muscle. Therefore, we conclude that the ELR may contribute to inspiratory muscle fatigue, not only by directly increasing the inspiratory activity but also by suppressing expiratory activity.

Dietary copper deficiency significantly attenuates nitric oxide (NO)-mediated vascular smooth muscle relaxation and vasodilation. There is evidence for both increased inactivation of the NO radical by superoxide anion, and oxidative damage to the endothelium where NO is produced. The current study was designed to examine the NO synthetic pathway in the endothelium during copper deficiency. Male weanling rats were fed a copper-adequate (CuA, 6.4 mg Cu/kg diet) or copper-deficient (CuD, 0.4 mg Cu/kg diet) diet for four weeks. Cremasteric arterioles (approximately 100 microm diameter) were isolated and used for the experiments. Western blot analysis of the arteriole endothelial nitric oxide synthase (eNOS) concentration did not show a difference between dietary groups. Acetylcholine (Ach)-induced vasodilation was significantly reduced in the CuD group both before and after pretreatment with the eNOS substrate L-arginine. Endothelial intracellular calcium ([Ca2+]i) stimulated by 10(-6) M Ach was significantly inhibited in the arterioles from CuD rats. Coincident with the inhibition of [Ca2+]i and vasodilation was a depression of vascular Cu/Zn-SOD activity and an increase in plasma peroxynitrite activity. These data suggest that endothelial Ca2+ signaling and agonist-stimulated NO-mediated vascular dilation are likely reduced by increased oxidative damage in copper-deficient rats.

Objective: To determine if the enhanced pressure-induced constriction of arterioles isolated from hypertensive rats is mediated by the endothelium., Methods: We utilized isolated, cannulated first-order arterioles (80 to 110 microns, i.d.) from the rat cremaster muscle of spontaneously hypertensive (SHR) and normotensive (WKY) rats. Arteriolar diameter was measured in response to changes in intraluminal pressures as well as various pharmacological agents in the presence and absence of an intact endothelial cell lining., Results: All arterioles developed intrinsic tone (approximately 74% of passive). Pressure-diameter relationships over a pressure range of 30 to 170 cm H2O demonstrated that the myogenic response of arterioles derived from both WKY and SHR was not dependent upon an intact endothelium. However, at higher pressures (> 170 cm H2O) the ability of the denuded arteriole from the SHR to maintain a constricted diameter was completely abolished. Treatment of arterioles from the SHR having intact endothelium with diclofenac (10(-5) M; 30 min) to inhibit the effect of cyclooxygenase had no effect on the high pressure constriction. In contrast, application of BQ-123 (10(-7) M; 30 min), an ET-A receptor blocker used to inhibit vascular smooth muscle responses to endothelin, completely abolished the arteriolar constriction at higher pressures., Conclusions: Therefore, in the hypertensive, arteriolar vasomotor responses to changes in intraluminal pressure is due to at least two mechanisms; one that is intrinsic to vascular smooth muscle (i.e., myogenic) and a second that involves an endothelial cell release of endothelin.

Background: Renal function declines with age and this may be related to changes in the expression or activity of various signal transduction proteins in the kidney., Methods: The present study compared the expression and activity of G alpha i(1-3) and G alpha s phosphorylation of mitogen activated protein kinases (MAP-K) (44 and 42 kd) and the activity of tyrosine kinase in renal cortical homogenates of young (4-month-old) and aging (14-month-old) rats., Results: The GTP/(GTP + GDP) binding ratio of G alpha s was significantly decreased in the kidney cortex of aging rats compared to young rats, while the GTP/(GTP + GDP) binding ratio of G alpha i(1-3) increased significantly in kidney cortex of aging rats. Tyrosine kinase activity and phosphorylation of MAP-K (44 and 42 kd) were also reduced in the kidney cortex of aging rats compared to young rats., Conclusions: These results suggest that diminished phosphorylation of MAP-K and tyrosine kinase activity as well as changes in the binding of GTP/(GTP + GDP) to G alpha i(1-3) and G alpha s may contribute to the age-related decline in renal tubular and vascular function seen in aging animals.

Microtubules are important cytoskeletal elements that have been shown to play a major role in many cellular processes because of their mechanical properties and/or their participation in various cell signaling pathways. We tested the hypothesis that depolymerization of microtubules would alter vascular smooth muscle (VSM) tone and hence contractile function. In our studies, isolated cremaster arterioles exhibited significant vasoconstriction that developed over a 20- to 40-min period when they were treated with microtubule depolymerizing drugs colchicine (10 microM), nocodazole (10 microM), or demecolcine (10 microM). Immunofluorescent labeling of microtubules in cultured rat VSM revealed that both colchicine and nocodazole caused microtubule depolymerization over a similar time course. The vasoconstriction was maintained over a wide range of intraluminal pressures (30-170 cmH(2)O). The increased tone was not affected by endothelial denudation, suggesting that it was due to an effect on VSM. Microtubule depolymerization with demecolcine or colchicine had no effect on VSM intracellular Ca(2+) concentration ([Ca(2+)](i)). These data indicate that microtubules significantly interact with processes leading to the expression of vasomotor tone. The mechanism responsible for the effect of microtubules on vasomotor tone appears to be independent of both the endothelium and an increase in VSM [Ca(2+)](i).

Objective: We conducted bioassay experiments to determine whether nitric oxide produced by endothelial cells (endothelial-derived nitric oxide, or EDNO) within large venules could act to dilate arterioles., Methods: In these experiments parallel segments of first-order arterioles and venules were isolated from skeletal muscle and were cannulated in series with a glass connecting tube (length: 300-500 microns). Arterioles were mechanically denuded of endothelium by a delicate yet abrasive rubbing technique. Venular endothelium remained intact. Endothelial denudation of arterioles was confirmed by the absence of dilation during exposure to acetylcholine (10(-6) mol/L). The cannulated vessels were pressurized to 30 cm H2O and the arterioles pre-constricted by approximately 50% with norepinephrine (10(-10) mol/L)., Results: Topical applications of acetylcholine (10(-6) mol/L) or bradykinin (10(-9) mol/L) during luminal perfusion from venule to arteriole produced significant arteriolar dilation. In contrast, a slight arteriolar constriction was observed when the direction of flow was reversed (i.e., arteriole to venule) in the presence of either acetylcholine (10(-6) mol/L) or bradykinin (10(-9) mol/L). Inhibition of venular EDNO with NG-monomethyl-L-arginine (L-NMMA; 10(-5) mol/L; 1 hour) completely abolished the arteriolar dilation observed in response to acetylcholine or bradykinin during venule to arteriole perfusion., Conclusions: These results demonstrate that venular-derived EDNO can relax arteriolar vascular smooth muscle.

Recent studies from this laboratory demonstrated that bradykinin transiently elevates intracellular Ca2+ and inhibits Cl-reabsorption in the in vitro microperfused medullary thick ascending limb (mTAL) of the rat. The present study was designed to identify the intracellular signaling mechanism(s) that mediate this response. Preincubation with the intracellular calcium chelator BAPTA (10(-5) M) completely eliminated the bradykinin-dependent increase in intracellular Ca2+ and the suppression of Cl- transport. Preincubation with the cGMP-dependent protein kinase inhibitor H-89 (10(-5) M) had no effect on the transport response to bradykinin. In contrast, 17-octadecynoic acid (17-ODYA; 10(-5) M), a suicide-substrate inhibitor of renal cytochrome P450 omega-hydroxylase, completely blocked the transport response to bradykinin, while the cyclooxygenase inhibitor sodium meclofenamate (10(-5) M) had no effect. Finally, addition of the cytochrome P450 omega-hydroxylase metabolite 20-hydroxyeicosatetraenoic acid (20-HETE; 10(-8) M) to the bathing medium significantly inhibited Cl- transport in the mTAL (delta -39 +/- 6.0%; p < 0.05), while the epoxygenase metabolite 5,6-epoxyeicosatrienoic acid (5,6-EET; 10(-8) M) had no effect. These data suggest that the bradykinin-dependent inhibition of Cl- transport in the mTAL of the rat is mediated by cytochrome P450 dependent metabolite(s) of arachidonic acid.

The purpose of this study was to determine whether the vascular myogenic response is enhanced in hypertension. Experiments were conducted in the intact cremaster muscle microcirculation as well as in isolated arterioles of hypertensive (SHR) and normotensive (WKY) rats. Increasing venous pressure in vivo by approximately 5 mmHg had no effect on normotensive first- (1A) or third-order arteriolar (3A) diameters; in contrast, hypertensive 1A diameter decreased 4% (89 +/- 2 to 85 +/- 3 microns) with an 8% decrease in 3A (24 +/- 2 to 22 +/- 2 microns). To further examine this enhanced constriction to elevated intravascular pressure in SHR, diameter was monitored in isolated 1A during step increases and decreases in intraluminal pressure. Normotensive arterioles displayed myogenic responses between pressures of 50 and 170 cmH2O; in contrast, hypertensive arterioles demonstrated myogenic responses over an extended pressure range (50-210 cmH2O). In addition, the change in diameter for each step change in pressure was greater in the arterioles from SHR, indicating an increased myogenic responsiveness. The myogenic reactions were unaffected by alpha-receptor blockade with phentolamine (10(-6) M), indicating that adrenergic hypersensitivity was not involved in the enhanced response to stretch. Morphometric analysis of the vascular wall revealed no differences in wall thickness, cross-sectional wall area, or wall-to-lumen ratio between normotensive and hypertensive rats. The length-tension relationships for normotensive and hypertensive rats demonstrated that peak active tension occurred at nearly the same vascular smooth muscle length. In addition, SHR arterioles were capable of maintaining higher levels of active tension that WKY arterioles, indicating an altered length-tension curve in chronic arterial hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

The influence of flow on endothelial intracellular calcium concentration ([Ca2+]i) was determined in intact, isolated arterioles by selectively loading endothelial cells with the calcium-sensitive fluorescent dye fura-2. A fluorescence microscope coupled to a digital image processor was used to simultaneously measure fura-2 fluorescence and microvessel diameter. Flow through the arteriole significantly increased endothelial [Ca2+]i and dilated arterioles. Acetylcholine also increased in endothelial [Ca2+]i and caused vasodilation. In comparison, adenosine did not alter endothelial [Ca2+]i but dilated arterioles. Removal of the endothelium abolished the responses to flow and acetylcholine but not adenosine. These results provide strong support for the involvement of calcium in endothelium-dependent dilation of isolated arterioles by flow and agonists and emphasize the importance of studying endothelial function in intact vessels.

Ion transport properties of pulmonary small airway epithelia are poorly understood. To characterize these properties, airways were excised from anesthetized pigs. Transepithelial potential difference (PD) and conductance were measured in five airway regions: trachea (T, 7.9 +/- 0.2 mm diam), mainstem bronchi (MB, 5.5 +/- 0.2 mm diam), large bronchi (LB, 1.69 +/- 0.12 mm diam), small bronchi (SB, 0.70 +/- 0.06 mm diam), and bronchioles (BR, 0.25 +/- 0.05 mm diam). T and MB were mounted in Ussing-type chambers, and LB, SB, and BR were cannulated with pipettes and perfused. PDs of control tissues were -9.7 +/- 0.8 mV (T), -4.0 +/- 0.5 mV (MB), -4.3 +/- 1.0 mV (LB), -4.5 +/- 0.4 mV (SB), and -1.5 +/- 0.4 mV (BR), lumen negative. Amiloride significantly (P < 0.05) inhibited PDs by 25-70% in all airway regions and decreased conductance 17-33% in all regions except LB where a 10% increase was observed. Bumetanide significantly reduced the amiloride-insensitive PD 54-62% in all regions except BR. Bumetanide had little effect on conductance in T, SB, and BR, but conductance was increased in MB and LB. All airways except the smallest BR significantly hyperpolarized when the solution that bathed the lumen was replaced with Cl(-)-free solution. In bronchioles, hyperpolarization by luminal Cl(-)-free solution was inversely related to fractional inhibition of PD with amiloride but directly related to lumen diameter. These results suggest that 1) porcine tracheas, bronchi, and bronchioles actively absorb Na+, and 2) secretion of Cl- may occur in all airway regions except small bronchioles.

Vascular smooth muscle calcium was measured during agonist treatment or pressure-induced stimulation of the myogenic response in isolated first-order skeletal muscle arterioles. Arterioles (40-180 microns) with spontaneous tone were isolated from rat cremaster muscle and cannulated. Arterioles were loaded with the calcium-sensitive dye fura-2 and excited at 340 and 380 nm. Images of vessel fluorescence were formed with a fluorescence microscope and digitized using an image processor coupled to a low light level camera. The fluorescent images allowed individual vascular smooth muscle cells to be seen within the arteriolar wall. Fluorescent intensity of the vessel wall, expressed as the ratio of fluorescence at 340 nm/380 nm, was used to estimate changes in vessel wall calcium. Topical application of norepinephrine (10 microM) to the arterioles caused a rapid and sustained constriction of the arterioles (64% of basal diam). The calcium response was biphasic consisting of a transient spike to 271% of basal followed by a decrease to a new steady state at 143% of basal. In comparison, steady-state indolactam (1 microM) produced a similar degree of constriction without an increase in calcium. Adenosine significantly dilated (35%) the arterioles and produced a decrease (24%) in vessel wall calcium. To investigate the myogenic response, intravascular pressure was step increased from 90 to 130 cmH2O. Increasing intravascular pressure caused an initial increase in vessel diameter of approximately 5% followed by active constriction that returned diameter to basal diameter. In association with this diameter change, estimated vessel wall calcium increased rapidly 8 +/- 2% and then continued to increase more slowly and remained elevated at 10-15% above basal levels. This study demonstrates the successful application of calcium-imaging technology in isolated arterioles for study of the role of calcium in arteriolar function. Results indicate that the calcium-contraction relationship differs for different agonists and are further consistent with a role for pressure-induced increases in vascular smooth muscle calcium during the myogenic response.

The goal of this study was to determine whether the endothelium played a role in the myogenic response of skeletal muscle arterioles. First-order arterioles (n = 15) were isolated from the rat cremaster muscle and cannulated for in vitro study. The development of spontaneous tone reduced the diameter of the isolated arterioles from 166.7 +/- 7.6 microns to 89.2 +/- 7.2 microns. The arterioles were exposed to step changes in intraluminal pressure over a range of 10-170 cmH2O and had no flow through their lumen. The vessels exhibited active constriction to step increases or active dilation to step decreases in pressure (50-150 cmH2O). At 90 cmH2O, arterioles dilated by 89.2 +/- 6.0% in response to the endothelium-dependent vasodilator acetylcholine (10(-6) M; ACh) and 89.6 +/- 10.9% in response to endothelium-independent dilator adenosine (10(-4) M; Ado). The endothelium was physically denuded by rubbing the vessel lumen. After denudation, the arteriolar dilation to ACh was abolished, whereas the dilation to Ado was unaltered. The absence of endothelium was verified by electron microscopy. Basal tone and the response to changes in pressure were not significantly different from endothelium-intact vessels. These studies indicate that the endothelium is not responsible for myogenic activity or development of spontaneous tone in skeletal muscle arterioles.

Little information exists as to the cellular events that couple the myogenic contractile response of an arteriole to an acute rise in intravascular pressure. The aim of this study was to examine whether protein kinase C (PKC), which has been implicated in the contractile response to agonists, contributes to myogenic vasoconstriction of cremaster muscle arterioles. Studies were performed on anesthetized rats, enclosed in an airtight Plexiglas box, with the cremaster exteriorized into a bath containing Kreb's solution. Pressure in the box was increased to elevate intravascular pressure by 20 mmHg. To examine PKC involvement, studies were performed in the absence or presence of inhibitors of PKC: H 7 (10(-9)-10(-5) M) or staurosporine (10(-10)-10(-7) M). Inhibitors were added to the tissue bath and produced no observable systemic effects or alterations in arteriolar diameter. Third-order arteriole (16 +/- 1 microns diam) responses to these agents and alterations in intravascular pressure were monitored by in vivo microscopy and vessel diameter was measured with a video caliper. H 7 produced a concentration-dependent inhibition of myogenic vasoconstriction, inhibiting the extent of constriction by 75% at 10(-5) M. Similarly, staurosporine caused a concentration-dependent inhibition of pressure-induced constriction. At 10(-7) M staurosporine the myogenic response was inhibited by 82%. Further support for a role for PKC in the myogenic response was provided by the observation that indolactam (10(-6) M), a stimulator of PKC activity, induced myogenic reactivity in first-order arterioles, which under basal conditions show passive distension to increased intravascular pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Communication from venules to arterioles through the release of endothelial-derived relaxing factor (EDRF) was evaluated. To demonstrate that the rat intestinal and the spinotrapezius muscle arterioles can respond to EDRF, the vessels were dilated by iontophoretically applied acetylcholine (ACh), and this dilation was greatly attenuated by the inhibitors of EDRF actions, methylene blue (100 microM) and dithiothreitol (50 microM). The EDRF inhibitors did not suppress arteriolar dilation to typically applied adenosine (10(-4) M), an endothelium-independent dilator. Although ACh release onto the venular wall had minimal effects on the diameter of the venule, the paired arteriole would dilate 20-30% in the intestine and 50-60% in the spinotrapezius muscle. After EDRF inhibition, venular ACh exposure did not cause arteriolar dilation. ACh diffusion from venules to arterioles was not the cause of arteriolar dilation, because release of ACh into the tissue at the same distance as from the arteriole to the venular ACh release site caused minimal arteriolar dilation. Neither blockade of neural reflexes with tetrodotoxin (3 X 10(-6) M) nor suppression of prostaglandin formation with indomethacin (10(-5) M) prevented the arteriolar dilation during release of ACh onto the venular wall. The overall study indicated that communication from venules to arterioles through the release of EDRF from the venule did occur and caused substantial arteriolar vasodilation. Therefore circumstances within and around venules may influence regulation of nearby arterioles through an EDRF-mediated mechanism.

The clinical experience of 21 Duke medical students during their family medicine clerkship is analyzed to compare experience in model family practices with that in private family practices. In model practices where 50 percent of the time involved patient care, students saw an average of 41 different patients for 45 encounters and 73 problem contacts during the month. In private practices with 100 percent time devoted to patient care, students saw 140 patients for 193 encounters and 346 problem contacts during the month. Most patients were seen in the physician office in both sites (89.0 percent model and 70.4 percent private), but fewer were seen as hospital inpatients in the model than in the private practices (6.3 vs 25.7 percent). The types of patient problems were alike, with the same 11 problems ranking in the top 15 most frequently seen in the two locations. The major difference in experience relates to the larger volume of patients and problems encountered in the private than in the model sites.

A new mutation causing spherocytic, hemolytic anemia has been discovered in the house mouse. It is inherited as a single autosomal recessive gene, allelic with both sph and ha, which, in turn, were shown to be allelic with each other. A revised nomenclature for the three apparent alleles is proposed: sph (formerly sph), sphha (formerly ha), and sph2Bc (the new mutation). Like the other murine hemolytic anemias, sph2Bc involves a defect in the red blood cell membrane protein, spectrin.

Indirect evidence suggests that the genetic defect in hereditary spherocytosis lies in the erythrocyte membrane skeleton, a submembranous meshwork of proteins (principally spectrin, actin, and protein 4.1) responsible for membrane shape and structural stability. To test this premise we systematically assayed the interactions of spectrin, the major skeletal protein, in six kindreds with autosomal dominant hereditary spherocytosis. In one these kindreds, enhancement of spectrin-actin binding by protein 4.1 was reduced, owing to a 39 +/- 4 per cent decrease (mean +/- S.D) in the binding of normal protein 4.1 by spectrin, in all of four members with the disorder. The defective spectrin was separated into two populations by affinity chromatography on immobilized normal protein 4.1. One population (41 +/- 2 per cent) lacked the ability to bind 4.1, but the other functioned normally. Presumable, the nonfunctional spectrin was the product of the autosomal dominant gene responsible for the hereditary spherocytosis in this kindred.

The clinical experience of 40 Duke University medical students during their required two-month clinical clerkships is analyzed to compare experience on the traditional internal medicine, surgery, pediatrics, obstetrics-gynecology, and psychiatry clerkships with experience on a new family medicine clerkship. On the traditional clerkships, the students saw mostly hospital inpatients for an average of 36 different patients for 142 encounters and 300 problem contacts during a two-month rotation. On the family medicine clerkship, they saw mostly office ambulatory patients for an average of 184 patients for 236 encounters and 416 problem contacts. Traditional clerkships provided the most experience with neoplasms, blood problems, mental illness, obstetrical, perinatal, and congenital problems. The family medicine clerkship offered the most experience with circulatory, respiratory, digestive, neurological, musculoskeletal, and skin problems and with injuries. The family medicine clerkship contributed a substantive and important dimension to the clinical curriculum beyond that offered by the traditional five clerkships.