Search

Introduction This article describes the surgical component of the Continuing Promise 2018 (CP-18) medical training and military cooperation mission. We report on the surgical experience and lessons learned from performing peacetime ambulatory surgeries in a tent-based facility constructed on partner nation territory. Methods This CP mission was unique in utilizing a land-based expeditionary surgical facility. Institutional Review Board approval was obtained to collect prospective deidentified patient data and aggregate information on all surgical cases performed. Specific aims of this study included describing surgical patient characteristics and evaluating conservatively selected cases performed in this environment. Body mass index (BMI) was used as a crude screening tool for perioperative risk to assist patient selection. Our secondary aim was to report lessons learned from preparation, logistics, and host nation exchanges. The team coordinated medical credentialing and documentation of all medical supplies with each host nation. Advance teams collaborated with local physicians in country to arrange training exchanges and identify surgical candidates. Results The mission was conducted from February to April 2018. Only two of five planned partner nation visits were completed. The surgical facility supported 78 procedures over 14 surgical days, averaging over six cases performed per core surgical day. Patients were predominantly female, with a mean age of 25.4 and a mean BMI of 31.1. The average surgical time was 37.5 minutes, the average anesthesia time was 70 minutes, and the average recovery time was 47.6 minutes. No significant complications or adverse events were noted. Conclusions CP-18 was the first CP mission to perform elective ambulatory surgery on foreign soil using a tent-based facility in a noncombat, nondisaster environment instead of a hospital or amphibious ship. This mission demonstrated that such a facility may be employed to safely perform low-risk ambulatory surgeries on carefully selected patients. The Expeditionary Medical Unit, coupled with the fast transport vessel enabled rapid expeditionary surgical facility setup with significant military and disaster relief applications. Expansion of surgical indications should be performed carefully and deliberately to avoid complications and damage to international relationships.

Several studies have shown that a certain subpopulation of middle-aged rats have an attenuated preovulatory LH surge, and that this is an early indicator of a general decline in reproductive cyclicity. The pituitary glands of middle-aged animals with attenuated LH surges have been shown to be significantly less responsive to GnRH than those from young (Y) animals. The present study was designed to investigate the relationship between the in vivo LH surge and the in vitro secretory capacity of dispersed anterior pituitary gland cells from the same animals. Individual LH-secreting cells were also studied with respect to their LH secretory capacity and proportionate numbers in the pituitary gland using reverse hemolytic plaque assay (RHPA). Two groups of animals, young (4-5 months old) and middle-aged (10-12 months old), were sampled on the afternoon of proestrus to determine the amplitudes of their preovulatory LH surges. The middle-aged animals were then classified as either normal (MAN) or attenuated (MAA) with regard to the peak levels of the surges. On the next proestrus, dispersed anterior pituitary gland cells were prepared for either perifusion or RHPA. Perifused anterior pituitary gland cells were exposed to three 2.5-min pulses of GnRH(30 nM) at 60-min intervals. In the RHPA, red blood cells were treated with protein-A to allow coating with rabbit antiovine LH-beta, and then co-incubated with anterior pituitary gland cells. The cells were then treated with one of several concentrations of GnRH (0.01, 1.0, 10, or 100 nM).(ABSTRACT TRUNCATED AT 250 WORDS)

Brito AN, Sayles TE, Krieg Jr RJ, Matt DW. Relation of attenuated proestrous luteinizing hormone surges in middle-aged female rats to in vitro pituitary gonadotropin-releasing hormone responsiveness. Eur J Endocrinol 1994;130:540–4. ISSN 0804–4643 Prior to the cessation of regular cyclicity, middle-aged rats display pre-ovulatory luteinizing hormone (LH) surges of reduced magnitude. The present study was designed to identify whether middle-aged female rats with attenuated proestrous LH surges have alterations in pituitary responsiveness to gonadotropin-releasing hormone (GnRH). Young (4 months old) and middle-aged (10–12 months old) regularly cycling females were catheterized and sampled on proestrus to characterize their LH surge profiles. On the next proestrus (12.00 h), pituitaries were perifused individually and exposed to three pulses of GnRH (30 nmol/l). The patterns of the proestrous LH surges revealed that 12 of 22 middle-aged rats had attenuated surges (< 7 μg/l) while the remaining 10 middle-aged females had surges that were similar to those of young rats. Pituitaries perifused on the next proestrus showed similar basal LH release among the middle-aged and young females. However, the LH secretory rates following the second and third administration of GnRH, as well as the overall GnRH-stimulated LH secretory rates, were significantly decreased in middle-aged females with previously attenuated LH surges as compared to those from the young proestrous rats. In contrast, middle-aged rats with normal LH surges had pituitary LH responses that were no different from those of young females. These results indicate that a decrease in pituitary LH responsiveness to GnRH is only apparent in middle-aged rats that display attenuated proestrous LH surges. Dennis W Matt. Department of Obstetrics and Gynecology, Medical College of Virginia, Box 980034, Richmond, VA 23298, USA

The relationship between degree and duration of reduced food intake and the expression of liver insulin-like growth factor-I (IGF-I) and growth hormone receptor (GHR) mRNA in relationship to body weight gain was examined. The first experiment used 12 adult male Sprague-Dawley rats fed 60% of food intake of the 12 control rats. On days 10, 15 and 20, four rats from each group were sacrificed. Liver samples were homogenized in 4M guanidine thiocyanide and total liver RNA was isolated by cesium chloride gradient centrifugation. Compared to the controls, body weight gain of the animals on 60% food intake was significantly lower and was correlated with the reduction of liver IGF-I mRNA expressed in arbitrary densitometric units (ADU) [Control: 1.1±.06; rats on 60% food intake at 10 days: 0.9±.08; at 15 days: 0.8±.03 (P

Reproductive aging in female rats is associated with a transition from regular estrous cyclicity to an anovulatory condition described as persistent estrous (PE). This PE condition is characterized by continued follicular development with elevated circulating levels of estrogen and FSH. In an attempt to investigate further the age-related changes in neuroendocrine function of PE rats, we have developed a model through which the return of hypothalamic-pituitary and ovarian function can be assessed following the withdrawal of chronic LHRH agonist suppression. Subsequent to withdrawal of continuous (2.5 ,Lg/h for 12 days) LHRH agonist [DTrp, 6 Pro9-NHEt]-LHRH (LHRH-AG) treatment, circulating FSH concentrations in PE rats increase and remain elevated with an apparent absence of ovarian negative feedback, and these rats fail to return to estrous cyclicity. In the present studies, estrogen administration induced significant decreases in FSH secretion in PE rats following withdrawal of LHRH-AG treatment and ovariectomy (OVX), suggesting that the negative feedback response to estrogen is maintained in PE females. However, progesterone administration 2 days later failed to elicit a positive feedback response of gonadotropin secretion in PE females prior to LHRH-AG treatment, serum inhibin and 17[i-estradiol (E,) concentrations were similar in middle-aged PE rats and young cyclic females on proestrus, while FSH levels were significantly greater in PE rats. After withdrawal of LHRH-AG treatment, plasma FSH concentrations remained elevated in PE rats as compared to young rats despite similar increases in E,. However, increases in plasma inhibin were delayed and significantly attenuated in PE rats. These results demonstrate that the apparent absence of ovarian negative feedback in PE rats following LHRH-AG withdrawal is not related to a loss in the negative feedback responsiveness of the hypothalamic-pituitary axis to estrogen or to insufficient ovarian E, secretion, but rather to alterations in ovarian inhibin secretion. The causes for the paradoxical relationship between the tonically elevated estrogen and inhibin levels and the elevated circulating concentrations of FSH in middle-aged PE rats are not apparent; but this relationship may result from a decreased negative feedback effect of inhibin on the pituitary, changes in hypothalamic LHRH pulsatility, or alterations in the secretion of other ovarian factors in PE females.

This study compared the changes in pituitary and serum levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) at various times following ovariectomy (OVX) between young cyclic and middle-aged persistent-estrous (PE) rats and related these to the relative gene expression of the pituitary gonadotropin subunits. In intact animals, both pituitary and serum levels of LH were similar between these two age groups, while the LH beta mRNA expression was significantly (p0.05) greater in young rats. Following OVX in young rats, the serum LH levels markedly increased (p0.05) beginning on day 7 and reaching a maximum fourfold increase by day 9. In contrast, the post-OVX increases in serum LH in middle-aged females were significantly delayed. OVX significantly (p0.05) increased pituitary LH contents of young rats by day 5, but had no effect on LH contents in middle-aged females until day 30 post-OVX. These changes were associated with increases in LH beta mRNA expression in both young and middle-aged females, but the levels were significantly (p0.05) lower in middle-aged females. Both pituitary and serum levels of FSH were significantly (p0.05) higher in middle-aged PE than in young rats prior to OVX, while the FSH beta mRNA expression was similar in both age groups. Following OVX in young rats, serum FSH levels rapidly increased (p0.05) on day 3 and attained tenfold higher values by day 30.(ABSTRACT TRUNCATED AT 250 WORDS)

This study determined whether attenuated preovulatory luteinizing hormone surges in aging rats are associated with a decrease in pituitary luteinizing hormone content or luteinizing hormone beta-messenger ribonucleic acid expression on proestrus.Blood samples were taken every 90 minutes from 1:30 to 10:30 PM on proestrus in young (n = 8) and middle-aged (n = 12), regularly cyclic rats for plasma luteinizing hormone determination. On the next proestrus at 12 noon, rats were killed and the pituitaries were removed for luteinizing hormone content determination by radioimmunoassay and luteinizing hormone beta-messenger ribonucleic acid expression by dot blot analysis. Results were analyzed by one-way analysis of variance.Seven of the middle-aged rats had attenuated luteinizing hormone surges while the remaining five females had surges similar to those of young rats. On the next proestrus, all rats had similar quantities of pituitary luteinizing hormone. However, luteinizing hormone beta-messenger ribonucleic acid expression in middle-aged rats with attenuated luteinizing hormone surges was lower (p less than 0.05) than that of middle-aged and young rats with normal surges.Decreased luteinizing hormone beta-messenger ribonucleic acid expression, but not pituitary luteinizing hormone content at 12 noon on proestrus is correlated with attenuated luteinizing hormone surges in middle-aged rats.

Sex steroids are known to affect growth and growth hormone (GH) secretion throughout mammalian life. Early studies on the imprinting effects of testosterone (T) on growth and GH secretion in rats (1) showed that neonatal gonadectomy (GX) caused significant disruption of GH secretion in adult male rats. Treatment of neonatally GX male rats with T during neonatal and adult life restored a significant component of the GH pulsatile pattern. The presence of the ovary prevented the imprinting effect of T that would occur if female rats had otherwise undergone neonatal GX (2). These imprinting effects most likely involve the brain as the primary target.

During aging female rats enter an anovulatory condition with chronically elevated circulating levels of estrogen described as persistent estrus (PE). Since this endocrine state is dramatically different from the fluctuating steroid milieu of young regularly cycling females, interpretations of altered neuroendocrine responses in aged rats have been difficult to attribute to aging per se. In the present study, young cyclic and middle-aged PE rats were treated with an LHRH agonist, [DTrp6,Pro9-NHEt]-LHRH, continuously (2.5 micrograms/h) for 12 days to suppress gonadotropin and ovarian steroid secretion. On the evening of the first day of LHRH agonist (LHRH-AG) treatment both young cyclic and middle-aged PE rats showed marked (p0.01) increases in plasma LH and FSH followed by progressive decreases in gonadotropin secretion which reached significantly (p0.05) lower levels than pretreatment values by day 7. LHRH-AG treatment significantly (p0.01) reduced circulating 17 beta-estradiol (E2) levels in both young and PE rats while progesterone concentrations did not change. Following LHRH-AG treatment, ovariectomy (OVX) resulted in increases of plasma LH and FSH that were delayed and attenuated in PE rats as compared to those of young females. When compared to nontreated rats, 12 days of LHRH-AG treatment in both young and PE females had a minimal and transient effect on the post-OVX gonadotropin responses, suggesting that the endocrine status immediately prior to OVX does not profoundly influence the post-OVX responses in young cyclic and middle-aged PE rats. Furthermore, LHRH-AG treatment does not appear to have permanent inhibitory effects on the hypothalamic-pituitary axis.(ABSTRACT TRUNCATED AT 250 WORDS)