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Our primary objective for this study was to determine whether steady-state amounts of alpha- and LH beta-subunit mRNAs in the anterior pituitary are altered during sexual maturation in the bovine female. A secondary objective was to determine whether 17 beta-estradiol (E2) alters amounts of LH subunit mRNAs before onset of puberty. Heifers (7 mo old) were assigned to one of three treatments: 1) ovariectomized (OVX, n = 16); 2) OVX and administered E2 (OVXE, n = 16); or 3) ovary-intact (INTACT, n = 20). Pituitaries were collected at an estimated 120 days before onset of puberty (prepuberty) or 25 days before onset of puberty (peripuberty). Six INTACT heifers were used to determine time of puberty during the experimental period, and their pituitaries were collected 40 h after administration of prostaglandin F2 alpha (postpubertal INTACT group). Relative amounts of mRNAs for LH subunits in each pituitary were determined by Northern analysis and scanning densitometry. Amounts of alpha- and LH beta-subunit mRNAs were lower in pituitaries of INTACT heifers and OVXE heifers, regardless of stage of sexual maturation, than in those of OVX heifers. Amounts of alpha-subunit mRNA were similar in OVXE and INTACT heifers regardless of stage of sexual maturation. Amounts of LH beta-subunit mRNA did not change during sexual maturation in heifers in the INTACT group. Concentrations of E2 were higher and LH beta-subunit mRNA were lower in heifers from the prepubertal OVXE group than in heifers in all other treatment groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Our working hypotheses for this study were that 1) the profile of intrapituitary LH and FSH isoforms would be shifted toward acidic forms as sexual maturation progresses in the bovine female; and 2) concentration of 17 beta-estradiol (E2) in circulation during sexual maturation would be a major factor modulating the percentage of the more acidic isoforms. In addition, the biological-immunoreactive (B:I) ratios of each isoform of LH were evaluated at selected stages of sexual maturation. Heifers (7 mo of age) were assigned to one of three treatment groups: 1) ovariectomized (OVX; n = 16); 2) OVX and administered E2 (OVXE; n = 16); or 3) ovary-intact (INTACT; n = 14). Pituitaries were collected from heifers in each group at an estimated 120 days (prepubertal) of 25 days before puberty (peripubertal). A fourth group of 6 heifers remained intact (postpubertal INTACT) to determine time of puberty during the experimental period. Pituitaries of heifers assigned to the postpubertal INTACT group were collected during the follicular phase of the first or second estrous cycle postpuberty. Pituitaries were used for determination of relative amounts of gonadotropin isohormones. Tissue extracts of the pituitaries were chromatofocused on pH 10.5-4.0 gradients. The LH of all pituitaries resolved into thirteen isoforms that were designated isoforms A-L, and S, with isoform A the most basic form. Isoforms F and G (basic pH range) were the predominant isoforms of each chromatofocusing profile and comprised 50-60% of the immunoreactive LH. Isoforms J and K were the major isoforms eluting in the acidic pH range.(ABSTRACT TRUNCATED AT 250 WORDS)

The objectives of the present study were 1) to determine whether 17 beta-estradiol (E2) regulation of tonic secretion of LH and FSH is sexually differentiated in the bovine and 2) to evaluate the effects of various physiological concentrations of E2 on the profiles and concentrations of gonadotropins in circulation. This was accomplished by administering different numbers of implants containing E2 to gonadectomized bovine males and females. Mean age at initiation of the study was 18.5 mo. Animals received 1, 2, 4, 8, or 16 implants of E2 or a sham implantation. Mean concentrations of LH in circulation and amplitude of LH pulses were similar between males and females after administration of E2. There was a cubic response for mean concentrations of LH and amplitudes of LH pulses across the dosages of E2 administered; lower concentrations of E2 had little effect, whereas higher concentrations of E2 suppressed both mean LH and amplitude of LH pulses. A linear decline in frequency of LH pulses occurred as concentrations of E2 in circulation increased. A treatment x sex interaction resulted for mean concentrations of FSH in circulation. Low doses of E2 resulted in a greater enhancement of circulating concentrations of FSH in males than in females. Tonic secretion of LH in bovine males and females responded in a similar manner to administration of various physiological concentrations of E2; however, a differential response between sexes was observed for FSH.

The application of hydroxylapatite coatings promises marked improvement in the rapidity and durability of osseointegration for both dental and orthopedic metallic implants. Standard methods for the in vivo assessment of the performance of experimental implants include canine mandibular and femoral transcortical implantations. This study compared the results of the two procedures by use of similar HA-coated titanium implants. The results indicate that the rapidity of osseointegration and the maximum attachment strength for mandibular dental implants approximate those of the femoral transcortical implants, especially at longer post-operative intervals. We conclude that the two models are comparable for the purpose of evaluating the performance of this type of implant and can be used interchangeably by dental and orthopedic implant designers. HA-coating of titanium implants provides extensive osseointegration in both mandibular and long-bone models, with similar mechanical attachment strengths and histologic appearance.

Hydroxylapatite (HA)-coated and grit-blasted (non-HA-coated) titanium dental implants were inserted into healed extraction sites of canine mandibles. After six weeks, the animals were killed and the implants mechanically tested in torsion to failure. Interface attachment strength, implant/tissue compatibility, integrity of the HA coating, and the location of interface failure were evaluated. Mechanical testing demonstrated an interface torsional strength of 3.98 +/- 0.93 MPa for the HA-coated implants and 2.25 +/- 0.65 MPa for the grit-blasted implants. This represents a 76.9% improvement in the maximum torsional interface strength, and is statistically-significant (p = 0.0004). On qualitative histologic analysis, interface failure was seen to occur primarily at the HA/implant interface, although failure through the HA coating and regions of bone/HA interface failure were observed. The HA-coated implants had bone in direct apposition to their surface with no fibrous tissue interposition. The grit-blasted implants also had regions of direct bone-implant apposition, but these areas were limited to a smaller proportion of the total interface area. There was no evidence of breakdown or change in thickness of the HA coating.

The objective of the present study was to examine the involvement of opioid neuropeptides and E2 in regulating circulating concentrations of gonadotropins during sexual maturation in the bovine female. Prepubertal (immature) and postpubertal (mature) bovine females were used. Mean concentrations of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in circulation before and after administration of naloxone were determined in ovariectomized heifers administered E2 and ovariectomized heifers not administered E2. A linear decline (P less than 0.01) in opioid suppression of LH and FSH occurred during the experimental period in immature heifers receiving E2. This decline in opioid suppression of LH and FSH occurred during the same period of time that intact control heifers were initiating estrous cycles at puberty. Little change of opioid suppression of LH and FSH occurred during the experimental period in immature heifers not receiving E2 and mature heifers receiving E2. Our research indicates that opioid neuropeptides and E2 act together to regulate LH and FSH secretion during sexual maturation in the bovine female.

The hypothesis tested was that increasing concentration of 17beta-estradiol (E(2)) subsequent to luteolysis stimulates the preovulatory surge of LH and that a decline in E(2) after the initial rise is not necessary to trigger the preovulatory surge of LH in the bovine female. Beef cows were synchronized to Day 16 of the estrous cycle. At Hour 0, all cows were ovariectomized and received one of four E(2) treatments: 1) luteal phase E(2) (LE; n=5), 2) increasing then decreasing E(2) (DE; n=5), 3) increasing and subsequent maintenance of high E(2) (IE; n=4), and 4) no E(2) (NE; n=3). Cows in the LE group received one E(2) implant at Hour 0 which provided low concentrations of E(2). Cows in the DE group received one E(2) implant at 0, 8, 16, 24, 32 and 40 hours; implants were subsequently removed at 8-hour intervals, thus mimicking the preovulatory rise and fall of E(2). Cows in the IE group were treated with the same regimen of E(2) implants as cows of the DE group, except that no E(2) implants were removed. Blood samples were collected at Hour 0 and at hourly intervals from Hour 2 through 80, for serum LH and E(2) quantification. The number of cows responding with a surge of LH was 0/3, 0/5, 4/5 and 3/4 for the NE, LE, DE and IE treatments, respectively. The proportion of cows responding with an LH surge was different (P<0.01) when data for cows in the NE and LE groups were pooled and compared with the pooled data of cows in the DE and IE groups. The mean time of the LH surge was not different (P>0.80) for cows responding with an LH surge (DE and IE treatments). Thus, increased levels of E(2) greater than luteal phase concentrations are needed to initiate preovulatory surges of LH, and it appears that concentrations of E(2) need to reach a certain level but do not need to decrease after this initial rise to stimulate a surge release of LH.

Two experiments were conducted to test the following hypotheses: 1) exposure of beef heifers to sterile bulls increases the proportion of heifers attaining puberty by 14 mo of age and 2) rate of growth interacts with bull exposure to influence age at puberty in beef heifers. In Exp. I, heifers were assigned to one of two treatments: 1) heifers were exposed to bulls (BE; approximately 70-d period of exposure) or 2) heifers were isolated from bulls (NE) and served as controls. In Exp. II, heifers were assigned to either BE or NE treatments (175-d period of exposure to bulls) and were fed to gain at a moderate (MG; .6 kg/d) or high (HG; .8 kg/d) growth rate. Blood samples were collected twice weekly to determine concentrations of progesterone indicative of onset of corpus luteum function and puberty. In Exp. I a greater (P less than .05) proportion of heifers receiving the BE treatment than of heifers receiving the NE treatment initiated corpus luteum function by 14 mo of age. In Exp. II, there was a bull exposure x growth rate interaction (P less than .05). The effect of bull exposure was greater within the HG groups than within the MG groups. However, heifers fed to attain a moderate or high growth rate and exposed to bulls attained puberty at younger ages than heifers not exposed to bulls and fed to attain a moderate or high growth rate. Mean ages at puberty were 375, 422, 428, and 449 (pooled SEM = 8.6) d for heifers in the BE-HG, BE-MG, NE-HG, and NE-MG groups, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Our hypothesis was that alterations in pattern of gonadotropin secretion induced by level of dietary energy intake are dependent on direction of BW change. Beef heifers were assigned to one of two treatments 21 d after ovariectomy: 1) increasing followed by decreasing BW (I-D; n = 9) or 2) decreasing followed by increasing BW (D-I; n = 9). Heifers assigned to the I-D treatment received 15.4 Mcal ME/d (HE) from wk 0 to 8 followed by 4.3 Mcal ME/d (LE) from wk 9 to 16. Heifers assigned to the D-I treatment received the LE diet for the initial 8 wk followed by the HE diet for the subsequent 8 wk. At 2-wk intervals blood samples were collected at 10-min intervals for 11 h to determine the pattern of secretion and(or) concentration of gonadotropins in circulation (LH and FSH) and pituitary responsiveness to administration of 750 ng and 50 micrograms of LHRH. Frequency of LH pulses increased (P less than .05) in a quadratic fashion with increasing ADG in heifers in both treatment groups. Amplitude of LH pulses decreased (P less than .05) in a linear fashion with increasing ADG in heifers in both treatment groups and magnitude of this decline was greater (P less than .05) in heifers receiving the D-I treatment. Amplitude of response to 750 ng of LHRH decreased (P less than .05) in a linear fashion with increasing ADG in heifers receiving the D-I treatment but was unrelated to changes in ADG (P greater than .05) in heifers receiving the I-D treatment. When heifers in both treatment groups attained similar BW (P greater than .05; wk 14), amplitude of LH pulses, responsiveness to 750 ng of LHRH and mean concentration of FSH in serum were higher (P less than .05) in heifers receiving the I-D than in heifers receiving the D-I treatment. Thus, we accept the hypothesis that alterations in pattern of gonadotropin secretion in heifers fed diets with a low energy content are dependent on direction of BW change.

In addition to a working knowledge of general complications such as thromboembolism and infective endocarditis, optimal care of the patient with a prosthetic valve requires specific knowledge concerning the characteristics of a given patient's prosthesis. This may need to include the ability to identify the valve roentgenographically when history and records are unavailable. A 53-year-old woman with mitral stenosis secondary to rheumatic heart disease and status post a reported Bjork-Shiley mitral valve (MV) replacement 17 years prior to hospital admission was referred for evaluation of severe hemolytic anemia. Previous cinefluoroscopy in 1986 at the time of a cerebrovascular accident revealed a normally functioning caged disc prosthesis and not the tilting disc of a Bjork-Shiley prosthetic valve. The valve was not further characterized and she continued receiving warfarin therapy until May 1989 when she presented with laboratory findings showing a marked hemolytic anemia with a hemoglobin of 6.5 mg/dl and lactate dehydrogenase (LDH) value of 2100 IU. Echocardiography revealed normal valvular function without evidence of perivalvular leak. The patient was referred for further evaluation with chest roentgenogram at the time of hospital admission revealing a valve configuration characteristic of the Beall model 103/104 series that has been found to manifest progressive disc variance with a high degree of hemolytic anemia (despite normal noninvasive evaluation of MV function), disc tilting with intermittent regurgitation, and catastrophic disc embolization in extreme cases. The precise identification of valvular prosthesis in patients after valve replacement is crucial for optimal management. As in our case, the mere identification of a particular valve may necessitate certain management and therapy based on the natural history of that valve. In the absence of reliable history and/or records, the roentgenographic examination should lead to the precise identification.

This 20-yr study, using 584 beef heifers born in the spring of 1984 or 1985, was conducted to determine whether selection for growth traits affected age and weight at puberty. Heifers were from three Hereford lines selected for weaning weight, final weight, and final weight plus muscling score, a control line and a line of Angus cattle. In addition, heifers from reciprocal crosses among the selection lines, control and Angus groups were evaluated. Intact bulls and androgenized heifers fitted with marking harnesses were used to aid in detection of estrus for heifers born in 1984 and 1985, respectively. The time of puberty was identified by the first behavioral estrus. During both years, heifers were weighed at 56-d intervals; these weights were used to calculate weight at puberty. Mean age at puberty was determined using survival analysis; percentages of heifers that were pubertal by the end of the study were transformed to logits for analysis. Heifers born in 1985 were heavier (P less than .05) at puberty than those born in 1984. Heifers in lines selected for growth traits were younger at puberty (P less than .05; 20 d) than were heifers in the control line because of combined direct and maternal genetic effects. Heifers from the final weight, control (P less than .05) and weaning weight lines (P less than .10) weighed less at puberty than Angus heifers; selection line x Angus crossbred heifers were heavier at puberty (P less than .05) than their respective pureline or purebred contemporaries due to heterotic effects. Selection for weaning weight, final weight or final weight plus muscling score did not have a detrimental effect on age at puberty in heifers.

Peritoneovenous shunting (PVS) for intractable ascites has an extensive clinical experience, with several well-described complications. We recently noted an unusual complication of PVS with a Denver shunt. A 37-year-old woman who had placement of a shunt for chylous ascites 18 months prior to presentation demonstrated on a large, mobile mass filling the right atrium which, during atrial systole, partially prolapsed into the right ventricle. At cardiac surgery, a 4 X 10 cm mass with attachment to the tip of the shunt was found. Intracardiac ascitic pseudocyst is a potentially lethal complication of PVS with the Denver shunt which should be considered with a high index of suspicion and evaluated with echocardiography.

Mean concentrations of luteinizing hormone (LH) increase during the follicular phase of the estrous cycle in cows. The working hypotheses in the present study were (1) that increasing concentrations of 17 beta-estradiol (E2) during the follicular phase of the estrous cycle cause an increase in mean concentration of LH by increasing amplitude of pulses of LH, and (2) that increasing E2 concentrations during this stage of the estrous cycle decrease frequency of pulses of LH in bovine females. Day of estrus was synchronized in seventeen mature cows. Treatments were initiated on Day 16 of the experimental estrous cycle (Day 0 = estrus). At Hour 0 (on Day 16), 4 cows were lutectomized. Lutectomy of these cows (EE; n = 4) allowed for endogenous secretion of E2. The remaining cows were ovariectomized at Hour 0 and were assigned to one of three E2 treatments: luteal phase E2 (LE, n = 5), increasing then decreasing E2 (DE, n = 5), and no E2 (NE, n = 3). Cows in the group that received LE were administered one E2 implant at Hour 0, which provided low circulating concentrations of E2 similar to those observed during the luteal phase of the estrous cycle. Cows in the group that received DE were administered one E2 implant at Hour 0, and additional implants were administered at 8-h intervals through Hour 40; then, two implants were removed at Hours 48 and 56, and one implant was removed at Hour 64.(ABSTRACT TRUNCATED AT 250 WORDS)

The objective of the present study was to determine if postpubertal boars (12-13 months of age; 156 +/- 8 kg) with large testes had altered hypothalamic control of secretion of luteinizing hormone (LH). Seven boars with the highest estimated 150 d, paired testis weights from a line selected for large testes (769 +/- 60 g = mean weight of excised testes) and 8 boars from a control group (control, 544 +/- 20 g) were tethered in stalls and fitted with indwelling jugular catheters. Males were bled when they were intact, 14 days after castration and during administration of sodium pentobarbital anesthetic (subsequent to castration) to block secretion of endogenous LH-releasing hormone (LHRH). Blood samples were collected at 12-min intervals for 6 hr before and 1 hr after intravenous injection of LHRH in intact and castrated males. During anesthesia, LHRH was administered 4 times at 1-hr intervals and blood samples were collected every 6 min. All samples were analyzed for concentrations of LH and pooled samples were analyzed for concentrations of 17-beta estradiol (E2) and testosterone (T). In intact and castrated males, mean concentrations of LH, frequency and amplitude of pulses of LH, and concentrations of E2 and T were not different between boars of the two groups (P greater than .10). Response to exogenous LHRH was less (P less than .05) in intact males with large testes than in corresponding males from the control group (P less than .05). Fourteen days after castration, males that had larger testes before castration had less of a response to LHRH than males from the control group (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

The objective of the present study was to investigate endocrine control of LH in postpubertal boars with large testes. Eight boars with the highest estimated paired testis weights from a line selected for large testes and nine boars from a line selected at random were used. Blood samples were collected over a 13-h period at weekly intervals for 4 wk. Samples were collected at 12-min intervals for 12 h before and 1 h after exogenous LHRH. Boars were bled when they were intact during the initial week. The second and third blood collections were 7 and 14 d after castration. The fourth bleeding occurred 7 d after exogenous 17 beta-estradiol (E2) replacement. In intact boars, mean LH was similar between boars from the two groups, but amplitude of pulses of LH was lower in intact boars with large testes than in boars from the control line. Maximum concentration of LH after administration of LHRH was less in boars with large testes than in boars from the control group. Seven days after castration, characteristics of LH measured did not differ between males from the two groups. However, 14 d after castration, amplitude of pulses of LH and maximum concentrations of LH after LHRH were less in males from the group with large testes than in males from the control group. After E2 administration, amplitude of pulses of LH tended to be lower in males from the group with large testes than in males from the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Asplenia syndrome is a rare congenital complex of splenic agenesis, cardiac malformation, and malposition of the abdominal viscera. Prolonged functional survival is very uncommon, with death usually caused by severe infection or congestive heart failure. A 21-year-old man with typical asplenia syndrome who is currently asymptomatic and in his third year of college is described.

The objective of the present study was to characterize secretion of thymosin alpha 1 (A1) and thymosin beta 4 (B4) during different stages of ovarian function and pregnancy in bovine females. One hundred and thirty-five prepubertal heifers averaging 9 mo of age at the time the study was initiated were used. Estrous detection was conducted twice daily using intact bulls fitted with marking harnesses. Blood samples were collected at first behavioral estrus and at the time of rectal palpation for pregnancy. Heifers were weighed at the beginning of the study and every 56 days and additional blood samples were collected at those times. Plasma was harvested and radioimmunoassays were conducted to quantify concentrations of thymosin A1 and B4. Mean concentrations of thymosin A1 and thymosin B4 were determined during prepuberty, estrus during which conception did not occur, estrus during which conception did occur, pregnancy and in heifers that failed to attain puberty. Mean plasma concentrations of thymosin A1 and B4 were greater at estrus during which conception occurred than at any other period (P less than .01). Regressions of days prepubertal and days post conception on thymosin A1 and B4 were analyzed. During the 100 days prior to puberty, thymosin A1 and B4 did not change in the heifers that ultimately conceived. However, in the heifers that were never determined to be pregnant by rectal palpation, concentrations of both thymosin A1 and B4 increased linearly during prepuberty (P less than .01). A decline in thymosin A1 and B4 concentrations occurred in a quadratic fashion from conception through the first 100 d of pregnancy (P less than .01).(ABSTRACT TRUNCATED AT 250 WORDS)

We reviewed the records of 2,400 consecutive patients undergoing cardiac catheterization at USAF Medical Center Keesler between 1978 and 1984 and found 35 patients (1.5 percent of all cardiac catheterizations) aged 35 years or less (mean age, 32 years) who underwent cardiac catheterization after myocardial infarction. These 35 patients (group 1) were compared to a randomly selected group of 100 patients (group 2) aged 55 years or greater who underwent cardiac catheterization for evaluation of coronary artery disease during the same period. The two groups were compared in terms of angiographic features and risk factors for coronary artery disease. The patients in group 1 had a higher proportion of normal coronary arteries (14 percent [5 patients] vs 0; p less than 0.01) and single-vessel disease compared to group 2, while the incidence of three-vessel disease was much less (14 percent [5] vs 47 percent; p less than 0.001). Involvement of the left main coronary artery was uncommon in group 1 (3 percent [1] vs 15 percent in group 2; p less than 0.01). Risk factor analysis revealed smoking to be the most common risk factor in both groups (89 percent [31] in group 1 and 91 percent in group 2). Hypertension (28 percent [10] vs 48 percent; p less than 0.05) and diabetes (3 percent [1] vs 23 percent; p less than 0.01) were more common in group 2. Importantly, of 19 patients in group 1 who underwent cardiac catheterization for prognosis despite being asymptomatic and able to reach at least stage 4 on a Bruce protocol exercise test, none was found to have residual surgically correctable disease.

The working hypothesis was that the amount of increase in secretion of luteinizing hormone (LH) that results from positive feedback of 17 beta-estradiol (E2) is dependent on season of the year in mature bovine females. Seven beef cows, ovariectomized approximately 2 mo before the initiation of the experiment, were used in the initial year (1983) of the study. Three of the ovariectomized cows (OVX-E2) received an sc E2 implant, which provided low circulating levels of E2. The remaining four cows (OVX) were not implanted. Blood samples were collected serially (at 10-min intervals for 6 h) at each spring and fall equinox and at each summer and winter solstice. This protocol was replicated with a different group of cows in 1985 (OVX-E2, n = 4; OVX, n = 6). Concentration of LH in blood serum was quantified in all samples. Concentration of E2 in blood serum was measured in pools of samples from each serial blood collection. Concentrations of E2 were higher (P less than .05) in the implanted cows. Mean concentration of LH and amplitude of pulses of LH were higher (P less than .05) at each season of the year in cows that were ovariectomized and implanted with E2 than in cows that were ovariectomized and did not receive E2. An effect of season of the year on mean concentration of LH was detected (P less than .01). No influence of season or E2 was detected for frequency of pulses of LH. There was no significant treatment X season interaction.(ABSTRACT TRUNCATED AT 250 WORDS)

When ovaries are removed prior to puberty, administration of exogenous 17 beta-estradiol (E2) decreases concentrations of luteinizing hormone (LH) below that of ovariectomized heifers receiving no E2. Subsequent to the time age-matched intact heifers reach puberty, exogenous E2 increases secretion of LH in ovariectomized heifers above that of ovariectomized heifers receiving no E2. The hypothesis that E2 would inhibit gonadotropin secretion in bovine males during the time E2 no longer inhibited gonadotropin secretion in age-matched bovine females was tested. Males (n = 12) and females (n = 12) were gonadectomized at 241 +/- 3 days of age, and half of each sex (6 males and 6 females) were administered a 27-cm E2 implant. An additional group of males (n = 6) and females (n = 6) remained intact and served as controls. Blood samples were collected (to quantify LH and follicle-stimulating hormone [FSH]) from all animals at 15-min intervals for 24 h at 1, 7, 13, 17, 21, 25, 29, 33, 37, and 43 wk after gonadectomy. Additional blood samples were collected twice weekly from control females to monitor progesterone and onset of corpus luteum function (451 days of age). E2 inhibited frequency of pulses of LH (p less than 0.01) and decreased mean concentration of LH and FSH (p less than 0.01) at Week 1 in gonadectomized males treated with E2 compared to gonadectomized males not administered E2.(ABSTRACT TRUNCATED AT 250 WORDS)

The objectives of this experiment were to determine if subnormal levels of progesterone (P4) indicative of luteal insufficiency influence (1) pulsatile release of luteinizing hormone (LH), (2) the interval to the preovulatory surge of LH after removal of P4, and (3) the secretion of P4 during the estrous cycle subsequent to administration of subnormal levels of P4. On Day 5 (Day = 0 day of estrus) of the estrous cycle, cows received P4-releasing intravaginal devices (PRID) to produce normal (2 PRIDs; n = 7) or subnormal (0.5 PRID; n = 6) concentrations of P4. Five cows served as controls. On Day 10, serial blood samples were collected from all cows. Collection of blood samples was again initiated on Day 17 in cows receiving PRIDs. The PRIDs were removed and blood collection continued for 78 h. Daily blood samples were collected from all animals for 42 days subsequent to estrus (estrous cycles 1 and 2, respectively). During estrous cycle 1, mean concentration of P4 was lower (p less than 0.05) and frequency of pulses of LH was higher (p less than 0.05) in cows receiving subnormal P4 than in cows receiving normal P4 and control cows. Plasma concentrations of estradiol (E2) were higher (p less than 0.05) on Days 9-16 of estrous cycle 1 in cows receiving subnormal P4 than in cows receiving normal P4 or in control cows. Concentrations of E2 were greater (p less than 0.05) at 6, 18, and 30 h following removal of PRIDs in cows receiving subnormal P4 than in cows receiving normal P4.(ABSTRACT TRUNCATED AT 250 WORDS)

The means for distinguishing Escherichia from Aerobacter (Enterobacter) differ in laboratories and range from complete dependence on colonial reactions on typical gram-negative media to reliance on one or more of the classical indole, methyl red, Voges-Proskauer, citrate (IMViC) parameters. Three colonial types (one prejudged as Escherichia) of lactose-positive rods were catalogued on each of the most commonly used selective media, MacConkey Agar, Endo Agar, and E M B Agar. Each cultural type was presumptively diagnosed and then compared with the expected outcome of individual IMViC tests. The distribution of preliminary identifications was similar from growth patterns on MacConkey Agar and E M B Agar, but it differed markedly from Endo Agar. When organisms initially diagnosed by cultural methods were compared by single IMViC tests, it was found that for each colonial type one of the biochemical parameters was best suited. Thus, for those types initially considered Escherichia, the methyl red or Voges-Proskauer test results agreed most consistently; for other types, the citrate reaction was most satisfactory. In addition, when newly formulated reagent-impregnated paper strip methods for indole, Voges-Proskauer, and citrate were evaluated and compared to the standard methods, agreement was 97% for indole, 90% for Voges-Proskauer, and 95% for Simmons' citrate.

Plaques similar in appearance to those induced by phage were observed adjacent to chloramphenicol and tetracycline discs on Pseudomonas aeruginosa lawns used for the determination of antibiotic susceptibility. Thirteen strains were selected for study, 10 of which exhibited the plaquing phenomenon. The ability to form plaques induced by tetracycline was not related to any of the biochemical properties of the strains studied, their overall antimicrobial susceptibility pattern, or their pathological source. Some pseudomonad strains were capable of pyocin production; however, the relationship between plaque formation and pyocin production was not apparent. Supernatant fluids of resuspended plaque contents of eight strains originally demonstrating clearings could induce plaques on sensitive indicator lawns only when collected from tetracycline-induced plaque areas; supernatant fluids of the same strains could not produce clearings without previous exposure to the drug. Of the eight supernatant fluids capable of plaque induction, three were active on their homologous indicator lawns. In a subsequent survey of 95 P. aeruginosa strains, it was found that 28 isolates exhibited plaques. Of these, 17 were associated with tetracycline, 7 were associated with chloramphenicol, 3 were associated with triple sulfa; and 1 was associated with nalidixic acid.

The identification of prompt lactose-fermenting gram-negative rods has generally relied heavily upon colonial morphology coupled with one or more indole, methyl red, Voges-Proskauer, citrate (IMViC) parameters, hydrogen sulfide, and motility. Studies were undertaken to compare diagnoses dependent solely upon the more orthodox criteria to a system for identification based upon hydrogen sulfide, ornithine decarboxylase, and citrate utilization (HOC). The results suggest that the IMViC scheme of identification is neither consistent nor applicable when applied to the current nomenclature of the above group of organisms and should be discarded, whereas the HOC system may prove to be of significant value to clinical microbiologists.