Small bowel exploration and resection using single-port surgery: a safe and feasible approach.

AIM: The aim of this study is to demonstrate the efficacy of wireless capsule endoscopy for preoperative identification of bleeding sources and/or small bowel tumours in surgical patients and to evaluate the feasibility of single-port surgery in the treatment of such pathologies. METHOD: Five patients presenting with obscure gastrointestinal bleeding or/and mild small bowel obstruction were investigated to diagnose and localize the bleeding source or tumour using capsule endoscopy imaging, and, if necessary, with other investigative modalities. All patients were operated on using single-port surgery for small bowel exploration, lesion confirmation, small bowel resection and anastomosis. RESULTS: Small bowel pathology was successfully detected by video capsule endoscopy in three of four patients, and was further substantiated by contrast CT, double-balloon endoscopy or enteroclysis. Complete small bowel exploration, intra-operative identification and oncological resection of the involved segment and anastomosis (intracorporeal and extracorporeal) was successfully performed in all five patients using single-port access without any complication, morbidity or mortality. CONCLUSION: This study demonstrates the feasibility and safety of single-port small bowel resection performed after a high-quality preoperative localization of the tumour.

Laparoscopic extraperitoneal colostomy in elective abdominoperineal resection for cancer: a single surgeon experience.

AIM: Parastomal herniation of end colostomies can be chronically debilitating for patients and a difficult problem to treat. To prevent parastomal hernia (PSH) formation an extraperitoneal colostomy (EPC) approach has been developed in open colorectal surgery and some studies have suggested a potential advantage to this approach. Here we describe our technique of laparoscopic extraperitoneal stoma formation and present our experience to date. METHODS: We performed a retrospective analysis of consecutive patients undergoing a laparoscopic abdominoperineal resection between March 1999 and March 2011. We performed the EPC technique as follows: under laparoscopic guidance, a smooth tip instrument was used to gently separate the peritoneum from the posterior aponeurotic plane to create an extraperitoneal tunnel running from the skin incision to the left flank of the abdominal cavity to join the previously dissected paracolic gutter. The colon was exteriorized and the position was checked to ensure the absence of torsion or kinking. RESULTS: Twenty-two patients underwent a standard laparoscopic abdominoperineal resection with total mesorectal excision. Colostomy was constructed extraperitoneally (EPC) or transperitoneally (TPC) in 12 and 10 patients respectively. There were five complications requiring operative intervention: two stomal necrosis and one surgical site infection in the TPC group and two small bowel occlusions in the EPC group. Four patients from the TPC group developed PSH at 24, 36, 48 and 72 months respectively while there were no cases of PSH in the EPC group. CONCLUSION: Extraperitoneal laparoscopic colostomy showed a potential reduction of PSH in our series of patients.

Laparoscopic resection with transanal specimen extraction for sigmoid diverticulitis.

BACKGROUND: This prospective study evaluated the technical aspects and microbiological consequences of laparoscopic resection with transanal specimen extraction and per ano transcolonic stapler anvil insertion in patients requiring elective operation for previous diverticulitis. METHODS: Laparoscopic sigmoid colectomy was performed with three ports, and specimen extraction carried out transanally through a complete opening of the rectal stump. A triple-stapled anastomosis restored colonic continuity. Systematic intraoperative bacteriological sampling was performed. Intraoperative data as well as microbiological and postoperative outcomes were evaluated prospectively. RESULTS: Sixteen consecutive patients were studied over a 6-month period. All procedures were technically satisfactory, with a mean(s.d.) operating time of 120·9(41·9) min. No conversion or additional access was required. Four of the 16 patients developed complications, but none required intervention. Although polybacterial growth was present in all peritoneal culture samples, no infection-related complications were observed. Two patients had an extended course of perioperative antibiotic cover owing to overt peritoneal cavity contamination during surgery, and in two further patients antibiotics were instituted empirically following the development of postoperative fever alone. CONCLUSION: Transanal specimen extraction in addition to per ano transcolonic stapler anvil insertion allows laparoscopic sigmoid resection to be performed with just three ports. Although intraperitoneal bacterial contamination occurs, this does not appear to translate into infectious morbidity.

Transanal extraction of the specimen during laparoscopic colectomy.

AIM: To assess the current state of the art of transanal specimen extraction in colonic resections. METHOD: A systematic literature search was conducted including the terms 'transrectal or transanal specimen extraction', 'Natural Orifice Specimen Extraction' and 'laparoscopic colectomy' for the period from 1955 to May 2011. Exclusion criteria were abdomino-perineal resections, pull-through technique, experimental studies and paediatric population. RESULTS: Nineteen studies met the inclusion criteria, representing 154 patients. The overall postoperative complication rate was 10%. The risks of peritoneal contamination and sphincter dysfunction were evaluated by a single study of each. CONCLUSION: Transanal extraction is a feasible option to minimize incisions in colorectal surgery.

Technical aspects and outcome of a standardized full laparoscopic approach to the reversal of Hartmann's procedure in a teaching centre.

AIM: Laparoscopic reversal of Hartmann's procedure is technically demanding. We evaluated the technical aspects and outcome of a standardized approach in a single centre and examined the feasibility of including this into training curricula. METHOD: The procedure entails a laparoscopy for adhesiolysis and identification and mobilization of the rectal stump. Mobilization of the splenic flexure is performed if necessary, and a colorectal anastomosis is fashioned after introduction of the stapler anvil via the colostomy with intra-abdominal positioning and delivery into the proximal colonic segment to be anastomosed. The stoma is excised as the last step in the operation. RESULTS: Forty-two patients underwent the procedure over an 8-year period with either an expert (n=21) or trainee under expert mentorship (n=21) as first operator. Intra-operative data and postoperative outcomes were evaluated by retrospective review of clinical charts and theatre records. There was a 9.5% conversion rate and 0% mortality. One patient suffered a ureteric injury, while postoperative surgical complications occurred in 7 patients (including one clinical anastomotic leakage). The mean operative time was 117 min. There was no significant difference in intra operative technical parameters or postoperative clinical consequences between procedures performed by a trained surgeon or by a trainee under mentorship. CONCLUSION: Adherence to a standardized operative protocol and expert mentorship allows this technically demanding operation to be associated with low conversion and complication rates. The absence of any difference between procedures performed by a trainee or trained surgeon suggests that the operation can be included in training programmes for laparoscopic surgery.

In vitro fertilization and sperm cryopreservation in the black-footed cat (Felis nigripes) and sand cat (Felis margarita).

Studies of in vitro fertilization (IVF) and sperm cryopreservation have been conducted in several small cat species, but virtually no data exist for black-footed cats (Felis nigripes) (BFCs) or sand cats (Felis margarita) (SCs). The objectives of this study were 1) to compare in vitro motility and acrosome status of fresh and cryopreserved (frozen in pellets on dry ice or in straws in liquid nitrogen vapor) BFC and SC spermatozoa cultured in feline-optimized culture medium (FOCM) or Ham F-10, 2) to assess ovarian responsiveness in BFCs and SCs following exogenous gonadotropin treatment and laparoscopic oocyte recovery, and 3) to evaluate the fertility of fresh and frozen-thawed spermatozoa from both species using homologous and heterologous (domestic cat oocytes) IVF in the two culture media. Motility and acrosomal integrity of fresh and frozen-thawed spermatozoa from BFCs and SCs were similar (P > 0.05) in both media during 6 h of culture. Although effects were more pronounced in SCs, cryopreservation in straws was superior (P < 0.05) to cryopreservation in pellets for both species. Gonadotropin stimulation produced approximately 16 ovarian follicles per female, and >80% of recovered oocytes were of optimal (grade 1) quality. The BFC and SC spermatozoa fertilized 60.0%-79.4% of homologous and 37.7%-42.7% of heterologous oocytes in both culture media, with increased (P < 0.05) cleavage of homologous (SC) and heterologous (BFC and SC) oocytes in FOCM. These results provide the first information to date on the gamete biology of two imperiled cat species and further our capacity to apply reproductive technologies for their conservation.

Fecal endocrine profiles and ejaculate traits in black-footed cats (Felis nigripes) and sand cats (Felis margarita).

Information regarding the reproductive biology of black-footed cats (BFC) and sand cats (SC) is extremely limited. Our objectives were to: (1) validate fecal hormone analysis (estrogens, E; progestagens, P; androgens, T) for noninvasive monitoring of gonadal activity; (2) characterize estrous cyclicity, ovulatory mechanisms, gestation, and seasonality; and (3) evaluate male reproductive activity via fecal androgen metabolites and ejaculate traits. In both species, the estrous cycle averaged 11-12 days. In BFC (n=8), estrus lasted 2.2+/-0.2 days with peak concentrations of E (2962.8+/-166.3 ng/g feces) increasing 2.7-fold above basal concentrations. In SC (n=6), peak concentrations of E (1669.9+/-83.5 ng/g feces) during estrus (2.9+/-0.2 days) were 4.0-fold higher than basal concentrations. Nonpregnant luteal phases occurred in 26.5% (26 of 98) of BFC estrous cycles, but were not observed in SC (0 of 109 cycles). In both species, P concentrations during pregnancy were elevated (32.3+/-3.0 microg/g feces BFC; 8.5+/-0.7 microg/g feces SC) approximately 10-fold above basal concentrations. Fecal T concentrations in males averaged 3.1+/-0.1 microg/g feces in BFC and 2.3+/-0.0 microg/g feces in SC. Following electroejaculation, 200 to 250 microl of semen was collected containing 29.9 (BFC) to 36.5 (SC)x10(6) spermatozoa with 40.4 (SC) to 46.8 (BFC)% normal morphology. All females exhibited estrous cycles during the study and spermatozoa were recovered from all males on every collection attempt, suggesting poor reproductive success in these species may not be due to physiological infertility.

Dynamic changes in inhibin messenger RNAs in rat ovarian follicles during the reproductive cycle.

The alterations in morphology and function of the ovarian follicle as it matures, ovulates, and becomes a corpus luteum are dramatic. A variety of steroid and polypeptide hormones influence these processes, and the ovary in turn produces specific hormonal signals for endocrine regulation. One such signal is inhibin, a heterodimeric protein that suppresses the secretion of follicle-stimulating hormone from pituitary gonadotrophs. Rat inhibin complementary DNA probes have been used to examine the levels and distribution of inhibin alpha-and beta A-subunit messenger RNAs in the ovaries of cycling animals. Striking, dynamic changes have been found in inhibin messenger RNA accumulation during the developmental maturation of the ovarian follicle.

The impact of thyroidectomy on parathyroid glands: a biochemical and clinical profile.

INTRODUCTION: An evaluation of PTH levels during thyroid surgery may reflect the functional status of the parathyroids and be useful in identifying patients at risk for hypocalcemia. This study aims to monitor the parathyroid function during total thyroidectomy through intra-operative serial samples for calcium and PTH. MATERIALS AND METHODS: Forty-seven patients undergoing total thyroidectomy for different diseases were selected for the study. Patients underwent serum PTH and calcium sampling at the induction of anesthesia (T0) and after the first (T1) and the second (T2) lobectomy. Serum calcium was also drafted 24 h after the operation. RESULTS: Mean PTH at T0, T1, and T2 was, respectively: 32.1 pg/ml, 19.6 pg/ml, and 11.5 pg/ml. PTH was significantly higher at T0 when compared to T1 (p<0.0001). It was also significantly higher at T1 than at T2 (p<0.0001). At T1 PTH levels were below the normal range in 20/47 cases (42.5%) and at T2 in 31/47 cases (66%). Twenty-four h after surgery, 8 patients (17%) demonstrated a biochemical hypocalcemia. A PTH value at T0 in the upper (>70 pg/ml) or in the lower (<20 pg/ml) limits of the normal range was statistically related to post-operative hypocalcemia (p=0.017). DISCUSSION: The study seems to confirm that serum PTH during thyroidectomy does not represent a sensitive tool in precociously identifying hypocalcemic patients. Nevertheless, before surgery, a PTH concentration at the higher or lower normal limit may help to identify patients "at risk" of developing hypocalcemia.

Use of the Prostate Health Index for detection of prostate cancer: results from a large academic practice.

BACKGROUND: The Prostate Health Index (phi) outperforms PSA and other PSA derivatives for the diagnosis of prostate cancer (PCa). The impact of phi testing in the real-world clinical setting has not been previously assessed. METHODS: In a single, large, academic center, phi was tested in 345 patients presenting for diagnostic evaluation for PCa. Findings on prostate biopsy (including Grade Group (GG), defined as GG1: Gleason score (GS) 6, GG2: GS 3+4=7, GG3: GS 4+3=7, GG4: GS 8 and GG5: GS 9-10), magnetic resonance imaging (MRI) and radical prostatectomy (RP) were prospectively recorded. Biopsy rates and outcomes were compared with a contemporary cohort that did not undergo phi testing (n=1318). RESULTS: Overall, 39% of men with phi testing underwent prostate biopsy. No men with phi<19.6 were diagnosed with PCa, and only three men with phi<27 had cancer of GG⩾2. Phi was superior to PSA for the prediction of any PCa (area under the receiver operating characteristic curve (AUC) 0.72 vs 0.47) and GG⩾2 PCa (AUC 0.77 vs 0.53) on prostate biopsy. Among men undergoing MRI and phi, no men with phi<27 and PI-RADS⩽3 had GG⩾2 cancer. For those men proceeding to RP, increasing phi was associated with higher pathologic GG (P=0.002) and stage (P=0.001). Compared with patients who did not undergo phi testing, the use of phi was associated with a 9% reduction in the rate of prostate biopsy (39% vs 48%; P<0.001). Importantly, the reduction in biopsy among the phi population was secondary to decreased incidence of negative (8%) and GG1 (1%) biopsies, whereas the proportion of biopsies detecting GG⩾2 cancers remained unchanged. CONCLUSIONS: In this large, real-time clinical experience, phi outperformed PSA alone, was associated with high-grade PCa, and provided complementary information to MRI. Incorporation of phi into clinical practice reduced the rate of unnecessary biopsies without changing the frequency of detection of higher-grade cancers.

Influence of atrial fibrillation on cardiac brain natriuretic peptide release during haemodynamic stress in heart failure.

BACKGROUND: The determinants of release of brain natriuretic peptide (BNP) in heart failure (HF) are incompletely understood, particularly, the effect of heart rhythm and haemodynamic stress. AIMS: To investigate the effect of haemodynamic stress on cardiac BNP release in HF and differentiate this response for atrial fibrillation (AF) and sinus rhythm (SR). METHODS: In 18 HF patients (ejection fraction<40%, 9 in AF and 9 in SR) haemodynamics and BNP levels were measured from arterial and coronary sinus samples at baseline, after 10 min of 20 degrees passive head up tilt (HUT) and after 10 min of isometric handgrip (IHG) exercise. From these data, we calculated a transcardiac BNP gradient and compared results between the AF and SR cohort. RESULTS: During haemodynamic stress in both groups, there were no significance differences in left sided filling pressures. At baseline, there were no differences in BNP measurements between the SR and AF group. The transcardiac BNP gradient increased significantly in the SR (p=0.02) but not the AF cohort, after HUT. During IHG exercise, there was a significant decrease in cardiac BNP release in the AF cohort (p=0.03) but not the SR cohort. CONCLUSION: These data imply in HF, cardiac rhythm influences cardiac BNP release in response to haemodynamic stress.

Weight loss in overweight adults and the long-term risk of hypertension: the Framingham study.

BACKGROUND: Few studies address long-term effects of weight loss on risk of incident hypertension among overweight adults. METHODS: We evaluated weight loss among 623 overweight (body mass index [calculated as weight in kilograms divided by the square of height in meters] >/=25) middle-aged (aged 30-49 years) and 605 overweight older (aged 50-65 years) adults in Framingham, Mass. Subjects were classified first according to amount of weight lost over 4 years: (1) weight changed by less than 1.8 kg (stable weight), (2) lost 1.8 to less than 3.6 kg, (3) lost 3.6 to less than 6.8 kg, and (4) lost 6.8 kg or more. We also classified weight loss according to whether it was sustained during the next 4 years. RESULTS: After adjusting for age, sex, education, baseline body mass index, height, activity, smoking, and alcohol intake, weight loss of 6.8 kg or more led to a 21% to 29% reduction in long-term hypertension risk. After adjusting for cancer or cardiovascular disease occurring during follow-up, weight loss of 6.8 kg or more led to a 28% reduction in risk (relative risk [95% confidence interval], 0.72 [0.49-1.05]) for middle-aged adults and a 37% reduction (0.63 [0.42-0.95]) for older adults. Sustained weight loss led to a 22% reduction in hypertension risk (0.78 [0.60-1.03]) among middle-aged and a 26% reduction (0.74 [0.56-0.97]) in older adults. This risk reduction was strengthened by adjustment for prevalent cancer or cardiovascular disease during follow-up. CONCLUSION: A modest weight loss, particularly when sustained, substantially lowers the long-term risk of hypertension in overweight adults.

Racial differences in parental satisfaction with neonatal intensive care unit nursing care.

OBJECTIVE: Nurses provide parental support and education in the neonatal intensive care unit (NICU), but it is unknown if satisfaction and expectations about nursing care differ between racial groups. STUDY DESIGN: A prospective cohort was constructed of families with a premature infant presenting to primary care between 1 January 2010 and 1 January 2013 (N=249, 52% white, 42% black). Responses to questions about satisfaction with the NICU were analyzed in ATLAS.ti using the standard qualitative methodology. RESULTS: One hundred and twenty (48%) parents commented on nursing. Fifty-seven percent of the comments were positive, with black parents more negative (58%) compared with white parents (33%). Black parents were most dissatisfied with how nurses supported them, wanting compassionate and respectful communication. White parents were most dissatisfied with inconsistent nursing care and lack of education about their child. CONCLUSIONS: Racial differences were found in satisfaction and expectations with neonatal nursing care. Accounting for these differences will improve parental engagement during the NICU stay.

Increased adenosine monophosphate-activated protein kinase activity in rat hearts with pressure-overload hypertrophy.

BACKGROUND: Recent reports suggest that activation of adenosine monophosphate (AMP)-activated protein kinase (AMPK), in response to acute changes in cellular energy status in cardiac and skeletal muscles, results in altered substrate utilization. We hypothesized that chronic alterations in myocardial energetics in hypertrophied hearts (left ventricular hypertrophy, LVH) will lead to elevated AMPK activity, which in turn regulates substrate utilization. METHODS AND RESULTS: Using (31)P NMR spectroscopy and biochemical assays, we found that in LVH hearts, adenosine triphosphate (ATP) concentration decreased by 10%, phosphocreatine concentration decreased by 30%, and total creatine concentration was unchanged. Thus, the ratio of phosphocreatine/creatine decreased to one third of controls, and the ratio of AMP/ATP increased to 5 times above controls. These changes were associated with increased alpha(1) and alpha(2) AMPK activity (3.5- and 4.8-fold above controls, respectively). The increase in AMPK alpha(1) activity was accompanied by a 2-fold increase in alpha(1) expression, whereas alpha(2) expression was decreased by 30% in LVH. The basal rate of 2-deoxyglucose uptake increased by 3-fold in LVH, which was associated with an increased amount of glucose transporters present on the plasma membrane. CONCLUSIONS: These results demonstrate for the first time that chronic changes in myocardial energetics in hypertrophied hearts are accompanied by significant elevations in AMPK activity and isoform-specific alterations in AMPK expression. It also raises the possibility that AMPK signaling plays an important role in regulating substrate utilization in hypertrophied hearts.

Cloning and nucleotide sequence analysis of complementary deoxyribonucleic acid for bovine preproinsulin.

A cDNA library was prepared from poly(A+) RNA isolated from fetal bovine pancreas. Bacterial colonies were screened for sequences homologous to a rat preproinsulin I cDNA probe. Ten positive clones were selected at random and further studied. Northern blot analyses revealed that seven of these clones hybridized to a single RNA species, of approximately 400 nucleotides. Sequence analysis of one of these clones (pbI2885) revealed the entire structural region of bovine preproinsulin mRNA including a 72 nucleotide region encoding a signal peptide enriched in hydrophobic residues. The overall nucleotide homology between bovine and human preproinsulin mRNA was 76% for the preregion, 89% for the A chain, 83% for the B chain, and 68% for the C peptide (including a 15 nucleotide deletion).

Postnatal development of corticosteroid-binding globulin: effects of thyroxine.

The aim of this study was to examine the temporal and dose characteristics of the corticosteroid-binding globulin (CBG) response to T4 and to determine whether this response is due to stimulation of hepatic biosynthesis of CBG. When n-propylthiouracil (PTU)-induced hypothyroid pups were given a single injection of T4 (0.1 microgram/g BW) on postnatal day 5, 6, or 7, only pups treated on day 7 showed a significant increase in CBG. In a T4 dose-response study conducted with 5- and 8-day-old pups, older pups exhibited maximum CBG concentrations (Rmax) which were 2.5-fold higher than those of younger pups. The D1/2 (dose required to elicit half the maximum response) values were similar at both ages. The effect of T4 withdrawal on serum CBG was also studied in PTU-treated pups. T4 injection on postnatal days 5-19 resulted in a progressive rise in CBG. In pups treated with T4 on days 5-9 and then withdrawn from treatment through day 20, serum CBG showed no further increase but was maintained at an elevated level. Using a liver slice system to assess CBG production in vitro, livers from 14-day-old hyperthyroid pups produced 4.77 ng corticosterone bound/g liver, while livers from euthyroid pups produced no CBG. We conclude: 1) the response of CBG to T4 is a function of the age of the animal; between days 5 and 8 this is due to increased Rmax without any change in sensitivity to T4 (D1/2); 2) T4 is required not only to initiate but also to sustain the developmental increase in CBG; and 3) T4 elicits an increase in circulating CBG by stimulating its synthesis.

Ontogeny of immunoreactive insulin in the fetal bovine pancreas.

The aim of this study was to characterize the development of immunoreactive insulin (IRI) in the fetal bovine pancreas. Pancreatic IRI was acid extracted, and both pancreatic and serum IRI were quantitated by RIA. The amount of pancreatic IRI per wet tissue wt in first trimester fetuses was similar to that in the adult animal (8.2 +/- 0.7 and 5.9 +/- 1.7 U/g pancreas, respectively). IRI increased progressively during gestation, attaining 39.2 +/- 6.5 U/g pancreas in the third trimester, 7-fold higher than that in the adult. When pancreatic IRI concentrations were standardized for protein content of the extracts, a decrease was noted between the midsecond and third trimesters. This is most likely the result of dilution of the endocrine portion of the pancreas by the rapidly growing exocrine pancreas. IRI was also detectable in fetal sera from all three trimesters. In contrast to the profile for pancreatic concentrations of IRI, serum concentrations remained constant throughout gestation at approximately 20 microU/ml. Poly(A+)RNA was isolated from adult and fetal pancreata, and the relative levels of preproinsulin mRNA were assessed by DNA/RNA filter hybridization. There was a 2- to 3-fold increase in the relative level of preproinsulin mRNA in fetal pancreata between the first and second trimesters which was maintained through the third trimester. In the adult pancreas, preproinsulin mRNA levels were similar to those in the first trimester fetus. This profile for the ontogeny of pancreatic preproinsulin mRNA was similar to that for pancreatic IRI (units per pancreas) during fetal maturation. We conclude that in the bovine fetus: the endocrine pancreas synthesizes IRI during all three trimesters of development; pancreatic (units per g pancreas), but not serum, concentrations of IRI increase progressively as development proceeds; and the ontogeny of preproinsulin mRNA is paralleled by that of pancreatic IRI (units per pancreas).

Differential effects of in vitro glucocorticoids on luteinizing hormone and follicle-stimulating hormone secretion: dependence on sex of pituitary donor.

We have used a dynamic perifusion system to determine whether glucocorticoids exert a direct effect on the secretion of LH and FSH from rat anterior pituitaries. Anterior pituitary fragments from male, proestrous female, or metestrous female rats were perifused for 8 h in either the absence (basal secretion rate) or presence of pulsatile GnRH administration (50 ng/ml peak concentration). Perifusions used medium containing 0.05% ethanol (vehicle), 600 ng/ml corticosterone, or 600 ng/ml cortisol. GnRH-stimulated secretion of FSH was enhanced in pituitaries from both male and female rats after in vitro incubation with either corticosterone or cortisol. The basal secretion rate of FSH was also elevated in proestrous females after glucocorticoid treatment. The GnRH-stimulated secretion rate for LH was significantly decreased in pituitaries from male rats treated with either glucocorticoid. In contrast, pituitaries from proestrous rats responded to either cortisol or corticosterone with an increase in LH secretion. Metestrous pituitaries showed divergent effects of the glucocorticoids on LH secretion; corticosterone enhanced secretion rates, and cortisol effected a decrease. Our data demonstrate that 1) glucocorticoids exert a direct effect on the secretion of LH and FSH from male and female rat pituitaries; 2) glucocorticoids elicit different effects on the secretion of LH and FSH, suggesting that they act at separate sites to regulate LH and FSH secretion; and 3) the effect of in vitro glucocorticoid treatment on gonadotropin secretion is dependent on sex and cycle stage of the pituitary donor and may be linked to prior in vivo concentrations of estrogen.

Unilateral ovariectomy increases inhibin messenger ribonucleic acid levels in newly recruited follicles.

We have used the unilaterally ovariectomized (ULO) rat as an experimental model to assess transient relationships between follicular recruitment and inhibin mRNA levels in the ovary. Animals were divided into three experimental groups (ULO, sham-operated, and intact) and killed 0, 9, or 24 h postsurgery. Inhibin alpha- and beta A mRNA were measured within individual ovarian follicles by in situ hybridization. Serum FSH concentrations in ULO animals increased significantly at 9 h and returned to presurgery levels by 24 h. There was no effect of surgery on serum LH concentrations. In the ULO animals, compensatory follicular recruitment was observed in the remaining ovary at 24 h as a significant increase in the number of follicles with mean diameter greater than 350 micron. Two distinct populations of healthy maturing follicles, based on diameter and hybridization intensity, were observed in ovaries from 24 h post-ULO rats. The first class, NRF-1 (newly recruited follicle-1), were those recruited 48 h previously by the secondary FSH surge of the preceding cycle. These large follicles (greater than 500 micron mean diameter) hybridized to both inhibin probes. The second class of follicles (NRF-2), which represent those newly recruited by the ULO-induced increase in serum FSH, were smaller in size than NRF-1 (350-500 micron mean diameter). The intensity of hybridization of both inhibin probes to NRF-1 was higher than that to NRF-2 in the majority of follicles. Each NRF-1 contained higher levels of both alpha- and beta A-inhibin mRNA than nonrecruited follicles (150-350 micron diameter). These data suggest that subtle changes in serum FSH concentrations, which are sufficient to induce follicular recruitment into a size class capable of ovulating within a given cycle, play the additional role of enhancing inhibin mRNA levels in developing follicles.