Prolactin modulates the gonadotropin response to the negative feedback effect of testosterone in immature male rats.

The effects of hyperprolactinemia (hyperPRL) and hypoprolactinemia (hypoPRL) on pituitary gonadotropin secretion and the feedback sensitivity to testosterone (T) were evaluated in immature male rats. At 34 days of age, rats were divided into three groups: group 1, controls, injected with oil; group 2, treated with bromocriptine mesylate (CB-154; 250 micrograms in oil/rat X day); and group 3, subjected to the transplantation of one pituitary from an adult female rat under the kidney capsule and treated with oil. The treatments were continued for 14 days. On day 8, each of these groups were further divided into three subgroups: intact, castrated, and castrated plus T treated. T treatment consisted of injection of T propionate (TP; 50 micrograms in oil/rat) on alternate days starting immediately after castration. Blood samples were obtained by cardiac puncture throughout the study. Plasma PRL levels were significantly reduced by CB-154 treatment and significantly increased by the pituitary graft (P less than 0.001). In intact immature male rats, hyper- or hypoPRL did not affect plasma LH levels, whereas hyperPRL reduced (P less than 0.01) plasma FSH concentrations. The postcastration increase in circulating LH levels was significantly increased (P less than 0.001) in rats treated with CB-154 24 h after castration. Moreover, the suppressive effects of TP on plasma LH and FSH levels were significantly (P less than 0.05) attenuated in hypoPRL rats. In pituitary-grafted rats, effects of castration and TP replacement on plasma LH levels did not differ from those in control rats. These results demonstrate that subnormal levels of PRL reduce the sensitivity of the hypothalamic-pituitary system to feedback inhibition by T. In contrast to previous findings in the adult rats, acute hyperPRL in immature male rats did not affect the negative feedback action of T on gonadotropin secretion.

Gene therapy for cardiovascular disorders: is there a future?

Incidence of cardiovascular disease has reached epidemic proportions in spite of recent advances in improving the efficacy of pharmacotherapeutics. This has led many to conclude that drug therapy has reached a plateau in its effectiveness. As a result, our efforts have been diverted to explore the use of gene transfer approaches for long-term control of these pathophysiological conditions. The purpose of this review is to present various approaches that are being undertaken to provide "proof of principle" for gene therapy for cardiovascular diseases. Finally, we will discuss the future of gene therapy and other new technologies that may further advance this field of therapeutics.

Effects of a long-acting LHRH agonist preparation on plasma gonadotropin and prolactin levels in castrated male rats and on the release of prolactin from ectopic pituitaries.

We have examined the effects of a single subcutaneous injection of an LHRH agonist, D-Trp-6-LHRH, in biodegradable microcapsules of poly(DL-lactide-co-glycolide) on plasma gonadotropin and prolactin (PRL) levels in castrated and in castrated-hypophysectomized-pituitary grafted (CAST-APX-GRAFT) male rats. The results were compared to the effects of daily injections of the same LHRH agonist dissolved in saline. In castrated rats, there were no significant alterations in plasma LH or PRL levels during the 10 days following the injection of LHRH agonist microcapsules, while FSH levels were generally reduced. In castrated males given daily injections of 6 micrograms of LHRH agonist in saline, plasma LH levels were significantly reduced while plasma PRL levels were not changed. In CAST-APX-GRAFT rats, both D-Trp-6-LHRH microcapsules and daily LHRH agonist injections appeared to increase plasma PRL levels. The pattern of changes in PRL release in both groups was similar, with levels on day 6 being significantly higher than those measured on days 1, 3 and 10 after onset of treatment. As expected, LH and FSH levels in these animals were extremely low. Immunoreactive D-Trp-6-LHRH was consistently detectable in the plasma of CAST-APX-GRAFT animals after microcapsule administration, whereas in animals given daily injections of this agonist in saline, its plasma concentrations were often below the detectability limit of the employed assay. These findings suggest that the LHRH agonist, D-Trp-6-LHRH, is capable of causing a short term stimulation of PRL release from ectopic pituitaries. Elevation of plasma LH levels is apparently not required for this effect.

The effect of intermittent forces on eruption of the rabbit incisor.

Rabbits were prepared so that a variable capacitance displacement transducer (VCDT) could be used to monitor the eruptive movements of a previously-amputated lower incisor, and a strain gauge transducer mounted on a relay-controlled plate was used to place precisely controlled intermittent forces opposing the erupting tooth. Forces of one or three g were applied under time conditions of one second on, nine seconds off (1:9); one second on, three seconds off (1:3); and one second on, one second off (1:1). The data indicate that with force present for 10% of the time (1:9), there was little or no effect on eruption rate. In contrast, 50% time (1:1) produced essentially the same intrusive effect as continuous force, and 25% time (1:3) gave an intermediate response. The data are consistent with the hypothesis that force duration is more important than force magnitude for the vertical equilibrium, as is the case for facio-lingual equilibrium.

Red-green mixture thresholds in congenital and acquired color defects.

A color television display was used to measure thresholds for mixtures of red and green on a white background; red and green components could be either incremental, decremental or zero. Ellipses are fitted to a plot of green contrast as a function of red contrast, and it is argued that the length of the ellipse is a measure of red-green color discrimination and the width of the ellipse is a measure of luminance discrimination. It is shown that the technique reliably distinguishes normals from congenital color defectives and also protan from deutan subjects. For some cases of acquired color defects (e.g. optic neuritis), there is a roughly equal loss of color and luminance discrimination whereas, in other cases (e.g., hereditary optic atrophies), the loss of color discrimination is much greater than the loss of luminance discrimination.

Gene therapy to control hypertension: current studies and future perspectives.

Hypertension is a complex pathophysiological state that leads to serious complications, including heart failure, coronary artery disease, and abnormal renal function. While traditional therapies can be effective in controlling the effects of hypertension, they offer no long-term cure and often lead to patient noncompliance, thereby diminishing their effectiveness. These reasons, coupled with the recent developments in gene transfer and somatic cell gene delivery, led researchers to explore alternative options that can produce long-term control of hypertension. Gene therapy offers the potential to yield lasting antihypertensive effects by influencing the genes associated with hypertension. In this review, we will discuss the merits of sense versus antisense strategies in controlling hypertension. We also discuss the advantages and disadvantages of both viral and nonviral vector types for the systemic delivery of genes for hypertension research. Results of our research group on the retrovirus-mediated delivery of the angiotensin type I receptor-antisense on the prevention of hypertension and related cardiovascular pathophysiology will be summarized. Finally, we discuss the future of this gene therapy approach in the reversal and long-term control of hypertension.

A surgical approach to bilateral hypernephroma using "benchwork" excision and autotransplantation.

A case of bilateral hypernephroma treated by right heminephrectomy in situ and "benchwork" excision of two tumors from the left kidney followed by autotransplantation is presented. Follow-up examination has demonstrated good renal function with no evidence of tumor recurrence or metastasis. This case illustrates the feasibility of benchwork operation and its application to renal tumors, particularly when these tumors are bilateral and preservation of renal tissue is imperative. Long-term follow-up of patients managed by this technique is mandatory.

Mesh inguinal herniorrhaphy: a ten-year review.

Inguinal herniorrhaphy remains one of the most common surgical operations, with approximately 10 to 20 per cent performed for recurrence. Reviews by specialized hernia centers show mesh repair has a recurrence rate of 0.2 per cent. Detractors of this repair include increased cost, technical difficulty, and risk for infection. The purpose of this study was to compare mesh versus nonmesh inguinal herniorrhaphy at a large teaching institution. From 1985 to 1994, 892 patients underwent primary repair for inguinal hernia at the Veterans Administration Hospital at Memphis, TN. Patients were stratified by repair [Lichtenstein (Mesh), open anterior (Bassini, Marcy, McVay, and Shouldice), laparoscopic (Lap), and preperitoneal (Post)]. Operative time for Mesh repair (111 +/- 2 minutes) was longer than for Bassini or McVay (91 +/- 2 and 98 +/- 2 minutes; P < 0.05), and Lap repairs were longer than all others (192 +/- 16 minutes; P < 0.05). Hospital stay averaged 2.2 +/- 0.1 days for Mesh versus 2.6 +/- 0.1 days for all repairs combined (P = not significant). Mesh patients developed four wound infections (1.0%), none requiring mesh removal, versus nine infections (1.8%) in other groups (P = not significant). One Mesh patient (0.3%) developed recurrence, compared with 16 (3.5%) with open anterior repair (P < 0.01). Inguinal herniorrhaphy using an open mesh repair technique provides superior recurrence rates without increasing risk for infection, length of stay, or technical difficulty.

Recurrent inguinal hernia: preferred operative approach.

Inguinal herniorrhaphy remains one of the most common general surgical operations, with approximately 10 to 20 per cent performed for recurrence. Subsequent repairs provide considerable technical challenge, as well as substantially greater risk of developing further recurrence. Mesh repair is advocated by several specialized hernia centers, demonstrating re-recurrence rates less than 2 per cent. Detractors of this repair include cost, technical difficulty, and risk for infection. The purpose of this study was to compare results of mesh and nonmesh repairs for recurrent inguinal hernia, either using an anterior or posterior approach, at a large teaching institution. From January 1, 1985, to December 31, 1994, 146 patients underwent repair for recurrent inguinal hernia at the Veterans Administration Hospital at Memphis, Tennessee. Patients were stratified by type of repair: Lichtenstein (Mesh), open anterior (OA), Bassini, Marcy, McVay, Shouldice, and preperitoneal with or without mesh. Patient ages and weights were similar between groups. Mean operative time for Mesh repair (104 +/- 4 minutes) was longer than that for OA repairs (80 +/- 5 minutes, P < 0.05) or preperitoneal without mesh repairs (92 +/- 5 minutes, P < 0.05). Mesh-based posterior repairs had the longest operative times (116 +/- 5 minutes). Hospital stay averaged 2.8 +/- 0.3 days, similar among all groups. One wound infection (1.0%) occurred in patients undergoing Mesh repair, which required operative drainage. No patient required removal of mesh. Two patients in the Mesh group (5.9%) developed recurrence compared with four recurrences (18.0%) in patients undergoing OA repairs. Only one patient with a mesh-based posterior repair recurred (1.9%) compared to eight without mesh (21.6%, P < 0.01). Follow-up ranged from 2 to 12 years. Repair of recurrent inguinal hernia using either an anterior or posterior mesh repair technique, performed at a teaching facility, provides superior recurrence rates without increasing risk for infection or length of stay. Preperitoneal mesh based repair is the preferred technique.

Readiness to change drinking among heavy-drinking college students.

OBJECTIVE: The purpose of this study was to examine motivation to reduce alcohol consumption among heavy-drinking college students. Specific goals were to test the factor structure of the Stages of Change Readiness and Treatment Eagerness Scale (SOCRATES); present normative SOCRATES data for collegiate heavy drinkers; present a heuristic, using SOCRATES scales to determine stage of readiness to change heavy-drinking; and compare students at different stages of change on demographic and drinking variables. METHOD: Participants were 278 (187 female) undergraduates who reported at least one episode of heavy drinking within the past 3 months. Students completed the SOCRATES and other questionnaires that assessed current and past drinking and demographics. RESULTS: Confirmatory factor analysis provided modest support for the SOCRATES factor structure. Students were classified according to the transtheoretical model of change (67% Precontemplation, 20% Contemplation and 13% Action). Contemplators drank more often, consumed more alcohol, reported more heavy drinking episodes and experienced more alcohol consequences than the other groups. CONCLUSIONS: Two thirds of the heavy-drinking college students did not recognize a need to reduce their alcohol consumption, despite evidence of tolerance and negative drinking consequences.

Hormonal responses to female conspecifics in hyperprolactinemic male rats and mice.

Exposure to a female results in an acute release of LH and testosterone (T) in normal male rats and mice. This study was conducted to determine whether these hormonal responses are altered in hyperprolactinemic (hyperPRL) male rats in which copulatory behavior is known to be suppressed and in hyperPRL male mice in which it is not. Adult male CDF (F-344) rats were made hyperPRL either by grafting of three anterior pituitaries under the kidney capsule or by treatment with diethylstilbestrol (DES). Exposure of control males to receptive females for 10-15 min produced the expected two- to fourfold statistically significant elevations in plasma LH levels. In contrast, plasma LH levels in pituitary grafted or DES-treated males were not altered by female exposure. Male mice were pituitary grafted (two pituitaries per recipient) or sham-operated and housed individually with a female for 1 week. The resident females were then replaced with novel females in half of the cages and blood samples were taken from the males after 5 min exposure for determination of LH levels or after 45-60 min exposure for T levels. Female-induced LH and T elevations occurred in both hyperPRL and control groups. Failure of hyperPRL male rats to experience an increase in plasma LH levels in response to a female suggests abnormality of mechanisms controlling LHRH release. Suppression of LHRH release may be involved also in the induction of deficits of sexual behavior in these animals.

Graduate surgical trainee attitudes toward postoperative thromboprophylaxis.

BACKGROUND: Postoperative deep vein thrombosis (DVT) results in significant morbidity and mortality. Appropriate patient risk assessment and proper use of prophylactic measures is crucial. METHODS: We conducted a confidential survey of general surgery house staff. The survey addressed DVT risk factor recognition, proximal and distal DVT absolute risk estimation, DVT prophylaxis strategies, and vena cava filter and low-molecular-weight heparin (LMWH) use. RESULTS: Obesity, immobility, malignancy, and previous DVT were overwhelmingly recognized as risk factors. Age >40, recent myocardial infarction, lupus anticoagulant, varicose veins, and factor V Leiden were inadequately recognized as risks. Deep vein thrombosis risk in the setting of cancer was underestimated. Most selected appropriate prophylactic strategies; many misunderstood vena cava filter and LMWH indications. CONCLUSIONS: We have identified specific areas of misunderstanding about DVT risk and prophylaxis that, if appropriately addressed during educational sessions, will enable young surgeons to make safer and more effective future decisions regarding thromboprophylaxis.

Analysis of cocaine, benzoylecgonine, codeine, and morphine in hair by supercritical fluid extraction with carbon dioxide modified with methanol.

Supercritical fluid extraction (SFE) using CO2 modified with methanol (10%) was employed for the extraction of cocaine from human hair. Extraction conditions were developed by using designed experiments to characterize the effects of pressure, temperature, and percent methanol on the recovery of cocaine from hair. When compared to the conventional acid hydrolysis method for hair analysis, SFE was faster and gave higher recoveries. Amounts of cocaine, benzoylecgonine (cocaine metabolite), codeine, and morphine in a hair standard reference material were determined by SFE-gas chromatography/ mass spectrometry (GC/MS) and found to be in agreement with reported levels. Analyses of hair from forensic case studies are also reported.