Effect of transport on pulsatile LH release in ovariectomized ewes with or without prior steroid exposure at different times of year

The initial aim of the present study was to test whether the stress of transport suppresses LH pulsatile secretion in ewes. In a pilot experiment in the late breeding season, transport resulted in an unexpected response in three out of five transported, ovariectomized ewes pretreated with oestradiol and progesterone. Before transport, seasonal suppression of LH pulses had occurred earlier than anticipated, but LH pulsatility suddenly restarted for the period of transport. This finding was reminiscent of unexplained results obtained in ovariectomized ewes infused centrally with high doses of corticotrophin-releasing hormone after pretreatment with low doses of oestradiol with or without progesterone. Hence, an additional aim of the present study was to examine whether these latter results with corticotrophin-releasing hormone could be reproduced by increasing endogenous corticotrophin-releasing hormone secretion by transport. Subsequent experiments used groups of at least eight ovariectomized ewes at different times of the year with or without prior exposure to steroids to assess whether these unexpected observations were associated with season or the prevailing endocrine milieu. In the mid-breeding season, transport for 4 h in the absence of steroid pretreatment for 8 months reduced LH pulse frequency from 7.5 +/- 0.3 to 6.3 +/- 0.4 pulses per 4 h (P < 0.05) and LH pulse amplitude from 2.6 +/- 0.5 to 1.8 +/- 0.3 ng ml-1 (P < 0.05). Similarly, in the mid-breeding season, 34 h after the cessation of pretreatment with oestradiol and progesterone, transport suppressed LH pulse frequency from 6.1 +/- 0.4 to 5.5 +/- 0.3 pulses per 4 h (P < 0.05) with a tendency of effect on amplitude (6.2 +/- 2.7 to 2.61 +/- 0.6 ng ml-1; P = 0.07; note the large variance in the pretransport data). During mid-anoestrus, evidence of a suppressive effect of transport was only observed on LH pulse amplitude (4.7 +/- 0.6 versus 3.0 +/- 0.5 pulses per 4 h; P < 0.05) in ovariectomized ewes that had not been exposed to ovarian steroids for 4 months. Repetition of the pilot experiment with 12 ewes during the transition into anoestrus resulted in one ewe with LH pulses seasonally suppressed but increased by transport; 11 ewes had a distinct pulsatile LH pattern which was decreased by transport in six ewes. In anoestrus, there was no effect of transport on LH pulse frequency or amplitude in intact ewes, or those ovariectomized 2-3 weeks previously, with or without prior oestradiol and progesterone treatment. However, basal concentrations of cortisol were greater in anoestrus than in the breeding season, and the increment in cortisol during transport was similar in anoestrus and the breeding season but greater during the transition into anoestrus (P < 0.05). Progesterone concentrations increased from 0.31 +/- 0.02 ng ml-1 before transport to 0.48 +/- 0.05 ng ml-1 during the second hour of transport (P < 0.05). In conclusion, transport reduced LH pulse frequency and amplitude in ovariectomized ewes that had not been exposed to exogenous steroids for at least 4 months. In most animals, the previously observed increase in LH pulsatility induced by exogenous CRH was not reproduced by increasing endogenous CRH secretion by transport. However, in four ewes, transport did increase LH pulsatility, but only during the transition into anoestrus in ewes with seasonally suppressed LH profiles after withdrawal of steroid pretreatment.

Anthropomorphic carotid bifurcation phantom for MRI applications

Anthropomorphic carotid bifurcation flow phantoms that incorporate different stenotic geometries within the internal carotid artery have been developed. This technique produces high-fidelity, life-size vascular flow models that are compatible with magnetic resonance techniques. The models, in conjunction with a computer-controlled flow pump, address the need for a complex vascular geometry that can be used to verify magnetic resonance angiography (MRA) techniques that quantify stenosis severity and blood flow. Stenotic geometries, with up to 80% diameter reduction, have been fabricated in two different phantom materials. Plastic phantoms provide a durable, rigid geometry where the absolute dimensions of the model are well known. Agar gel phantoms provide tissue-like signal (T1, T2) up to the lumen boundary and are also compatible with ultrasound techniques. In this paper the technique to produce vascular flow phantoms is outlined and the compatibility of these phantoms with MRA techniques is demonstrated. J. Magn. Reson. Imaging 1999;10:533-544.

Serum leptin levels during the menstrual cycle of healthy fertile women

Leptin is a protein, produced by adipose tissue, which has cytokine and hormonal properties. Serum leptin levels can be considered as a measure of body fat mass, and are involved in regulation of body weight. Previous studies suggest that leptin may have an additional role in reproduction, and there is also evidence for involvement in the hypothalamic-pituitary-gonadal axis. In this study, we investigate the possible changes in serum leptin concentration throughout the menstrual cycle. Samples were collected from apparently healthy, fertile women at different stages in their menstrual cycle, timed precisely according to the luteinising hormone (LH) surge. Mean serum leptin levels were significantly higher in the luteal phase (median 11.4 ng/mL) than in the follicular phase (median 10.0 ng/mL) (P < 0.001). In addition, mean serum leptin levels correlated with body mass index (r = 0.54, P < 0.05), but showed no correlation with luteal-phase progesterone levels. Results showed that levels of serum leptin vary during the menstrual cycle, and add to the mounting evidence that leptin has a role in reproduction. These fluctuations should be taken into account whenever studies are performed using female subjects.

Leptin binding activity changes with age: the link between leptin and puberty

The timing of the physical transition from child to adult is determined by a biological clock that switches off the pituitary gonadal axis during infancy until puberty. Body composition (and in particular, fat mass), through leptin, are critical signals to this clock. However, no direct relationship between leptin and puberty has been demonstrated. Leptin is bound in the circulation by a high-affinity binding protein, which has been identified as a soluble leptin receptor. We found circulating levels of leptin binding activity (LBA) to be low at birth, to be high in the prepubertal years, to fall through puberty, and then to remain stable during adult life. LBA correlated with pubertal status in both boys and girls. We postulate that the fall in LBA, associated with increasing age and puberty, reflects a reduction in expression of truncated leptin receptors, and leptin is then available to the full-length receptor, which transmits the biological signal for leptin. The high levels of LBA occur during the years when the pituitary gonadal axis is quiescent. Thus, the change in LBA could explain how leptin regulates puberty.

Leptin binding activity changes with age: the link between leptin and puberty

The timing of the physical transition from child to adult is determined by a biological clock that switches off the pituitary gonadal axis during infancy until puberty. Body composition (and in particular, fat mass), through leptin, are critical signals to this clock. However, no direct relationship between leptin and puberty has been demonstrated. Leptin is bound in the circulation by a high-affinity binding protein, which has been identified as a soluble leptin receptor. We found circulating levels of leptin binding activity (LBA) to be low at birth, to be high in the prepubertal years, to fall through puberty, and then to remain stable during adult life. LBA correlated with pubertal status in both boys and girls. We postulate that the fall in LBA, associated with increasing age and puberty, reflects a reduction in expression of truncated leptin receptors, and leptin is then available to the full-length receptor, which transmits the biological signal for leptin. The high levels of LBA occur during the years when the pituitary gonadal axis is quiescent. Thus, the change in LBA could explain how leptin regulates puberty.

Effect of transport on pituitary responsiveness to exogenous pulsatile GnRH and oestradiol-induced LH release in intact ewes

This study examined the effect of transport on GnRH self-priming in vivo as well as the consequential effects on the oestradiol-induced LH surge. The follicular phases of ewes (eight per group) were synchronized with progestin sponges, and 50 micrograms oestradiol benzoate was injected 24 h (time zero) after sponge removal to improve precision in the timing of the LH surge. Beginning 8 h after oestradiol, saline or GnRH (500 ng, i.v.) was given at 2 h intervals with or without 8 h transport beginning 0.5 h before the first GnRH injection (late transport) and effects were compared with those observed during early transport, that is, starting 2.5 h before the first GnRH injection. In all ewes, GnRH alone induced a maximum LH response of 1.9 +/- 0.4 ng ml-1 after the first challenge. The response was enhanced (P < 0.01) after the second and third GnRH injections (7.4 +/- 1.4 ng ml-1 and 7.6 +/- 1.7 ng ml-1, respectively). This self-priming effect after the second GnRH was reduced by late transport (7.4 +/- 1.4 versus 4.2 +/- 0.8 ng ml-1; P < 0.05) but not early transport, that is, transport initiated closer to the time of GnRH administration had greater suppressive effects on LH secretion. Throughout transport, spontaneous LH pulse frequency was lower in treated than it was in control ewes (2.38 +/- 0.53 versus 4.50 +/- 0.53 pulses per 8 h; P < 0.01), with marked effects in the first 4 h of transport (1.0 +/- 0.19 versus 2.63 +/- 0.38 pulses per 4 h; P < 0.02). Spontaneous pulse amplitude also tended to decrease during transport (0.13 +/- 0.02 versus 0.20 +/- 0.03 ng ml-1; P = 0.07). When LH turnover was stimulated by exogenous GnRH, the onset of the LH surge was delayed (controls: 20.5 +/- 2.0 h versus GnRH alone: 25.3 +/- 1.5 h; P < 0.05) and the duration was reduced (8.5 +/- 0.9 versus 6.5 +/- 0.4 h; P < 0.05). Transport tended to delay the LH surge in saline-treated ewes (20.5 +/- 2.0 versus 22.9 +/- 1.9 h; P = 0.08), with a further delay imposed by late transport plus GnRH (27.5 +/- 1.6 h; P < 0.05) but not by early transport plus GnRH (27.8 +/- 2.5 versus 26.4 +/- 2.4 h; P > 0.05), that is, effects mediated by increasing LH turnover were only manifest if transport occurred near the LH surge, when there was insufficient time to replenish stores of releasable LH. In all transported ewes, plasma cortisol increased from 4.5 +/- 1.0 ng ml-1 to 29.2 +/- 5.5 ng ml-1 (P < 0.001) within 15 min of the start of transport and was significantly lower (P < 0.01) by 6.5 h. Plasma progesterone also increased from 0.30 +/- 0.04 to 0.38 +/- 0.04 ng ml-1 (P < 0.05). In conclusion, transport affected the oestradiol-induced LH surge by causing a 50% reduction in the self-priming effect of exogenous GnRH, but hypothalamic effects were also revealed by a two-fold decrease in spontaneous LH pulse frequency in saline-treated ewes.

Effect of transport on pulsatile and surge secretion of LH in ewes in the breeding season

The aim of this study was to elucidate the mechanism(s) involved in stress-induced subfertility by examining the effect of 4 h transport on surge and pulsatile LH secretion in intact ewes and ovariectomized ewes treated with steroids to induce an artificial follicular phase (model ewes). Transport caused a greater delay in the onset of the LH surge in nine intact ewes than it did in ten ovariectomized ewes (intact: 41.0 +/- 0.9 h versus 48.3 +/- 0.8 h, P < 0.02; ovariectomized model: 40.8 +/- 0.6 h versus 42.6 +/- 0.5 h, P < 0.02). Disruption of the hypothalamus-pituitary endocrine balance in intact ewes may have reduced gonadotrophin stimulation of follicular oestradiol production which had an additional effect on the LH surge mechanism. In the ovariectomized model ewes, this effect was masked by the exogenous supply of oestradiol. However, in these model ewes, there was a greater suppression of maximum LH surge concentrations (intact controls: 29 +/- 4 ng ml-1 versus intact transported 22 +/- 5 ng ml-1, P < 0.02; ovariectomized model controls: 35 +/- 7 ng ml-1 versus model transported 15 +/- 2 ng ml-1, P < 0.02). Subsequent exposure to progesterone for 12 days resulted in the resumption of a normal LH profile in the next follicular phase, indicating that acute stress leads to a temporary endocrine lesion. In four intact ewes transported in the mid-follicular phase, there was a suppression of LH pulse amplitude (0.9 +/- 0.3 versus 0.3 +/- 0.02 ng ml-1, P < 0.05) but a statistically significant effect on pulse frequency was not observed (2.0 +/- 0.4 versus 1.7 +/- 0.6 pulses per 2 h). In conclusion, activation of the hypothalamus-pituitary-adrenal axis by transport in the follicular phase of intact ewes interrupts surge secretion of LH, possibly by interference with LH pulsatility and, hence, follicular oestradiol production. This disruption of gonadotrophin secretion will have a major impact on fertility.

Effect of adrenocorticotrophic hormone (ACTH1-24) on ovine pituitary gland responsiveness to exogenous pulsatile GnRH and oestradiol-induced LH release in vivo

The present experiment was designed to determine if and how exogenous ACTH replicates the effects of stressors to delay the preovulatory LH surge in sheep. Twenty-four hours after oestrous synchronisation with prostaglandin in the breeding season, groups of 8-9 intact ewes were injected with 50 microg oestradiol benzoate (0 h) followed 8 h later by 3 injections of saline or GnRH (500 ng each, i.v.) at 2 h intervals (controls). Two further groups received an additional 'late' injection of ACTH (0.8 mg i.m.) 7.5 h after oestradiol, i.e., 0.5 h before the first saline or GnRH challenge. To examine if the duration of prior exposure to ACTH was important, another group of ewes was given ACTH 'early', i.e. 2.5 h before the first GnRH injection. The first GnRH injection produced a maximum LH response of 1.9+/-0.4 ng/ml which was significantly (p < 0.01) enhanced after the second and third GnRH challenge (7.1+/-1.5 ng/ml and 7.0+/-1.7 ng/ml, respectively; 'self-priming'). Late ACTH did not affect the LH response after the first GnRH challenge (1.9+/-0.4 vs. 1.8+/-0.3 ng/ml; p > 0.05) but decreased maximum LH concentrations after the second GnRH to 35% (7.1+/-1.5 vs. 4.6+/-1.1 ng/ml; p = 0.07) and to 40% after the third GnRH (7.0+/-1.7 vs. 4.0+/-0.8 ng/ml; p = 0.05). When ACTH was given early, 4.5 h before the second GnRH, there was no effect on this LH response suggesting that the effect decreases with time after ACTH administration. Concerning the oestradiol-induced LH surge, exogenous GnRH alone delayed the onset time (20.5+/-2.0 vs. 27.8+/-2.1 h; p > 0.05) and reduced the duration of the surge (8.5+/-0.9 vs. 6.7+/-0.6 h; p > 0.05). The onset of the LH surge was observed within 40 h after oestradiol on 29 out of 34 occasions in the saline +/- GnRH treated ewes compared to 11 out of 34 occasions (p < 0.05) when ACTH was also given, either late or early. In those ewes that did not have an LH surge by the end of sampling, plasma progesterone concentrations during the following oestrous cycle increased 2 days later suggesting a delay, not a complete blockade of the LH surge. In conclusion, we have revealed for the first time that ACTH reduces the GnRH self-priming effect in vivo and delays the LH surge, at least partially by direct effects at the pituitary gland.

BEAUTY-X: enhanced BLAST searches for DNA queries

BEAUTY (BLAST Enhanced Alignment Utility) is an enhanced version of the BLAST database search tool that facilitates identification of the functions of matched sequences. Three recent improvements to the BEAUTY program described here make the enhanced output (1) available for DNA queries, (2) available for searches of any protein database, and (3) more up-to-date, with periodic updates of the domain information.

AVAILABILITY

BEAUTY searches of the NCBI and EMBL non-redundant protein sequence databases are available from the BCM Search Launcher Web pages (http://gc.bcm.tmc. edu:8088/search-launcher/launcher.html). BEAUTY Post-Processing of submitted search results is available using the BCM Search Launcher Batch Client (version 2.6) (ftp://gc.bcm.tmc. edu/pub/software/search-launcher/).

SUPPLEMENTARY INFORMATION

Example figures are available at http://dot.bcm.tmc. edu:9331/papers/beautypp.html

CONTACT

(kworley,culpep)@bcm.tmc.edu

The utility of head computed tomography after minimal head injury

OBJECTIVE

To determine if patients who present with a history of loss of consciousness who are neurologically intact (minimal head injury) should be managed with head computed tomography (CT), observation, or both.

METHODS

We prospectively studied patients who presented to our urban Level I trauma center with a history of loss of consciousness after blunt trauma and a Glasgow Coma Scale score of 15. All patients underwent CT of the head and were subsequently admitted for 24 hours of observation.

RESULTS

A total of 1,170 patients with minimal head injury were studied during a 35-month period. All patients had Glasgow Coma Scale scores of 15 on arrival and had a history of either loss of consciousness or amnesia to the event. Two hundred forty-seven patients (21.1%) were intoxicated with drugs or alcohol on admission; 39 patients (3.3%) had abnormalities detected by CT, including 18 intracranial bleeds; 21 patients (1.8%) had changes in therapy as a direct result of their CT results, including 4 operative procedures. No patient with negative CT results deteriorated during the subsequent observation period.

CONCLUSION

CT is a useful test in patients with minimal head injury because it may lead to a change in therapy in a small but significant number of patients. Subsequent hospital observation adds nothing to the CT results and is not necessary in patients with isolated minimal head injury.

Effect of prolonged exposure to oestradiol on subsequent LH secretion in ewes

Abnormal follicles can produce oestradiol continuously for up to 20 days and this inhibits the hypothalamic-pituitary axis. The present experimental series was designed to determine the minimum exposure to high or low follicular phase concentrations of oestradiol that were required to exert inhibitory effects on LH surge secretion induced by additional oestradiol administered at the end of continuous exposure to oestradiol. Experiments were also included to establish whether the inhibitory effects of prolonged oestradiol were mediated at the pituitary, and whether the failure of response to the oestradiol challenge could be corrected by exposure to normal luteal phase patterns of progesterone. Treatment of ewes between 2 and 12 days with 1, 2 or 4 oestradiol implants (3 cm) totally blocked the subsequent normal LH surge in response to an oestradiol challenge in 45 of 52 ewes pretreated with oestradiol. In the seven ewes that did have an increase in LH, the response occurred at the expected time but was greatly reduced (14 versus 40 ng ml-1), and occurred only in ewes pretreated with oestradiol implants for 2 or 4 days. We were unable to establish a robust linear time-dose relationship, i.e., when ewes were treated with lower doses of oestradiol (one or two implants) for a reduced time (2, 4 or 8 days), there was random distribution of the 7 of 32 animals that had a reduced LH surge after oestradiol challenge (with four implants or 50 micrograms injection). The present study is the first to show that exposure for only 2-4 days to continuous oestradiol at late follicular phase concentrations can disrupt LH surge release. However, in oestradiol-treated ewes, LH secretion was provoked by high or low doses (0.5 mg or 0.5 microgram) of GnRH, although it was reduced by 50%, and a GnRH self-priming effect was still evident. All of these results suggest that inhibitory effects occur at the pituitary and hypothalamus. It remains to be confirmed whether the major effect is at the pituitary by reducing GnRH receptor or LH synthesis, or at the hypothalamus via inhibition of GnRH secretion.

First Report of Powdery Mildew Caused by Sphaerotheca fusca on Tomatillo in California

Tomatillo or husk tomato (Physalis ixocarpa Brot.) is an annual Solanaceous bush grown for its fruit, which are harvested when the fruit fill the enlarged calyx and are used primarily in Hispanic cooking. In the summer of 1997, commercial field-grown tomatillo in the Salinas Valley (Monterey County) was severely affected by a powdery mildew disease. Fungal growth was found on leaves, petioles, and calyces and resulted in twisting, desiccation, and premature senescence of the tissues. The mycelium was white to gray, ectophytic, amphigenous, and effuse. Mycelial appressoria were indistinct. Conidiophore foot cells were straight, cylindric, measured 36.1 to 61.1 µm (mean 47.0) × 11.1 to 13.9 µm (mean 11.7), and were followed by 1 to 3 shorter cells. Doliform conidia were formed in chains and measured 25.0 to 50.0 µm (mean 32.5) × 11.1 to 22.2 µm (mean 17.7). The length-to-width ratios of conidia generally were less than 2.0, and fibrosin bodies were present. Germ tubes usually were laterally inserted, lacked conspicuous appressoria, and were of the pannosa-type. Cleistothecia were not observed. Based on these characters, the fungus was identified as Sphaerotheca fusca (Fr.) Blumer, Beitr. Krypt.-Fl. Schweiz (1). Pathogenicity was confirmed by gently pressing infected leaves onto leaves of potted tomatillo. Inoculated plants were kept in a chamber at 100% humidity for 48 h, and then maintained in a greenhouse. Powdery mildew developed on inoculated plants after 12 to 14 days, while uninoculated plants did not develop disease. The experiment was conducted a second time and the results were the same. This is the first report of a powdery mildew disease of tomatillo in California. Reference: (1) U. Braun. Nova Hedwigia 89:1, 1987.

Assessment of simple colorimetric procedures to determine smoking status of diabetic subjects

The performance of a simple colorimetric assay for urinary nicotine metabolites to assess smoking status in diabetic subjects (n = 251) was investigated. Several variations of the colorimetric assay and a qualitative extraction procedure were evaluated in comparison with a cotinine immunoassay as the "gold standard." Among these, the best overall performance was achieved with the qualitative test (sensitivity 95%; specificity 100%). The quantitative measurement of total nicotine metabolites performed less well (sensitivity 92%; specificity 97%) but could be improved by incorporating a blank extraction (sensitivity 98%; specificity 98%). Allowance for diuresis appeared to offer no advantage over the other methods. These results support previous findings regarding the use of these colorimetric procedures in nondiabetic subjects and, contrary to other recent observations, their performance was not impaired in diabetic patients.

Routine preoperative "one-shot" intravenous pyelography is not indicated in all patients with penetrating abdominal trauma

BACKGROUND

To determine which patients need a "one-shot" intravenous pyelogram (IVP) before laparotomy for penetrating abdominal trauma.

STUDY DESIGN

Over a 15-month period, 240 laparotomies were performed for penetrating trauma at our urban level I trauma center. Prospectively collected data included clinical suspicion of genitourinary injury, results of preoperative IVP, intraoperative findings, and operative decisions influenced by the IVP.

RESULTS

Preoperative IVP was performed in 175 patients (73%). Of these, 71 (41%) had suspicion of a renal injury based on the presence of a flank wound or gross hematuria. The IVP was believed to influence operative decisions in six patients, all in this group. Each of these six patients had either a shattered kidney or a renovascular injury and had a nephrectomy performed with the knowledge that a normal functioning kidney was present on the contralateral side. No patient without a flank wound or gross hematuria had an IVP that was judged to be helpful intraoperatively. Preoperative IVP was helpful only in patients with flank wounds or gross hematuria. Nephrectomy was performed in two additional patients who did not undergo IVP, both of whom presented in shock.

CONCLUSIONS

Routine preoperative IVP is not necessary in all patients undergoing laparotomy for penetrating trauma. The number of IVPs can be safely reduced by 60% if the indications are narrowed to include only those stable patients with a flank wound or gross hematuria.

A method of determining peritoneal penetration in gunshot wounds to the abdomen

BACKGROUND

It has previously been shown that 98% of gunshot wounds that penetrate the peritoneal cavity cause injuries that require surgical repair. Many gunshot wounds in the vicinity of the abdomen (GSWA) may actually be tangential and not penetrate the peritoneal cavity at all. Patients with such wounds may not require laparotomy. It is important to determine which patients with a potential tangential GSWA actually have penetration of the peritoneal cavity to minimize negative laparotomies. This study was undertaken to determine the sensitivity, specificity, and accuracy of diagnostic peritoneal lavage (DPL) in the determination of peritoneal penetration for patients who sustain GSWA.

METHODS

DPL was performed for all patients who had sustained a GSWA in whom peritoneal penetration was unclear, i.e., patients whose GSWA appeared to be tangential, thoracoabdominal, or transpelvic and for whom a clear indication for laparotomy (shock, peritonitis, etc.) did not exist. Our threshold for a positive DPL was 10,000 red blood cells (RBC)/mm3. A prospective data base was kept with information on the location of the wound, DPL result, findings at laparotomy, and outcome.

RESULTS

During a 4-year period, 429 consecutive DPLs were performed for GSWA at our urban Level I trauma center. One hundred fifty DPLs were positive, with more than 10,000 RBC/mm3. Six of these patients were found to have no peritoneal penetration at laparotomy (false-positive). The remaining 144 patients with positive DPLs were found to have operative injuries (true-positive). Of the 279 patients with DPL counts less than 10,000 RBC/mm3, 2 developed indications for laparotomy and were found to have intraperitoneal injuries (false-negative). The remaining 277 patients had no peritoneal injuries (true-negative). This was demonstrated either by laparotomy done for another indication (n = 7) or by uneventful inpatient observation for 24 hours (n = 270). The sensitivity, specificity, and accuracy of DPL in determining peritoneal penetration in GSWA is therefore 99, 98, and 98%, respectively.

CONCLUSION

For patients who sustain GSWA for whom peritoneal penetration is unclear, DPL is a sensitive, specific, and accurate test to determine the need for laparotomy. It remains our test of choice when confronted with these patients.

Effect of adrenocorticotrophic hormone on gonadotrophin releasing hormone-induced luteinizing hormone secretion in vitro

An in vitro perifusion study investigated the effect of different forms of adrenocorticotrophic hormone (ACTH) on gonadotrophin releasing hormone (GnRH)-induced luteinizing hormone (LH) secretion, particularly GnRH self-priming, and oestradiol sensitisation of the ovine pituitary. Fragments of pituitaries were obtained from mixed-breed adult nonpregnant female sheep (without corpora lutea, unless otherwise stated). The amount of LH released by different doses of GnRH (2.5 x 10(-10) M (n = 9 chambers), 1 x 10(-10) M (n = 9), or 5 x 10(-11) M (n = 6)) was evaluated by giving two GnRH pulses (5 min each) 2 h apart. In a duplicate set of chambers, ACTH1-24 (5 x 10(-7) M) was included in the perifusate 0.5 h before the first GnRH challenge. Potassium chloride (KCl; 100 mM) was administered 2 h after the second GnRH challenge to assess the viability of the tissue and the size of the releasable LH pool. Results were expressed as percentage of LH secretion. The influence of ACTH1-24 on oestradiol sensitisation was also examined using pituitaries obtained during the luteal phase. Pituitary tissues were perifused throughout with 1 x 10(-9) M or 6 x 10(-11) M oestradiol in the medium. The LH response to the second GnRH challenge (GnRH 2) was significantly greater (p < 0.01) than after the first (GnRH 1) at the highest dose of GnRH (2.5 x 10(-10) M; 2547 +/- 804 vs. 4547 +/- 1013%), but at the lower doses (1 x 10(-10) M or 5 x 10(-11) M), the self-priming effect of GnRH was not evident (3016 +/- 550 vs. 2932 +/- 490% and 841 +/- 205 vs. 711 +/- 87%). Treatment with ACTH1-24 (5 x 10(-7) M) did not affect tonic LH secretion nor the LH response to the first or second GnRH challenge at any of the GnRH doses tested. The LH released in response to KCl was also similar from control and ACTH1-24-treated tissue at all GnRH doses. Both lower doses of GnRH (1 x 10(-10) M or 5 x 10(-11) M) produced the self-priming effect when the pituitary tissue was sensitised with the higher dose of oestradiol (1 x 10(-9) M; 1711 +/- 239 vs. 5085 +/- 1307%, and 1502 +/- 376 vs. 2619 +/- 629%). In the presence of lower concentrations of oestradiol (6 x 10(-11) M), self-priming was observed only after the higher dose of GnRH (1 x 10(-10) M; 1293 +/- 214 vs. 2865 +/- 436%), not the lower dose (5 x 10(-11) M; 985 +/- 203 vs. 1271 +/- 436%). In spite of these differences, ACTH1-24 treatment did not affect LH secretion (neither basal nor potassium-induced). The effect of ACTH1-39 (1 x 10(-8) M or 5 x 10(-7) M; n = 6 chambers per combination) on GnRH-induced LH secretion was examined using the higher (2.5 x 10(-10) M) or lower dose of GnRH (1 x 10(-10) M), with or without oestradiol sensitisation (1 x 10(-9) M). At the lower dose (1 x 10(-8) M), ACTH1-39 influenced neither tonic nor GnRH-induced LH secretion. The LH released by KCl was also similar to the control and ACTH-treated tissue. In contrast, the higher dose of ACTH1-39 (5 x 10(-7) M) increased tonic LH secretion immediately after inclusion in the medium (104 +/- 3 vs. 161 +/- 20%), but suppressed the GnRH self-priming effect after 2.5 x 10(-10) M, i.e., the LH responses to GnRH 1 and 2 were similar (1786 +/- 294 vs. 1553 +/- 373%). However, the LH response to KCl was not significantly different (p > 0.05) between the control and ACTH-treated tissues (2333 +/- 286 vs. 2638 +/- 431%). When the effect of this higher dose of ACTH1-39 on oestradiol-priming was investigated, ACTH increased tonic LH secretion but suppressed the self-priming effect of GnRH (1 x 10(-10) M GnRH; 945 +/- 274 vs. 922 +/- 323%; p > 0.05), and decreased (p < 0.05) the LH released in response to KCl compared to the controls (1803 +/- 409 vs. 4302 +/- 1017%). In summary, in vitro, ACTH1-24 did not affect either tonic LH secretion, the GnRH self-priming effect, or oestradiol sensitisation. The entire ACTH1-39 increased tonic LH secretion, but reduced GnRH self-priming and oestradiol sensitisation. (ABSTRACT TRUNCATED)

Effects of cone-induction treatments on black spruce (Picea mariana) current-year needle development and gas exchange properties

Both drought and root pruning (RP) increased the number of cones induced when black spruce (Picea mariana (Mill.) B.S.P.) grafts were injected with gibberellins A(4/7) (GA), but their effects on predawn shoot water potential and current-year needle development differed. Drought decreased predawn shoot water potential (Psi(pd)), but only during the period when irrigation was withheld, and it had no effect on the growth or gas exchange properties of current-year needles. Conversely, root pruning had little effect on Psi(pd), but it resulted in trees with smaller current-year needles that had lower nitrogen and chlorophyll concentrations and reduced rates of gas exchange up to the later stages of shoot elongation compared with needles of control trees. These findings are discussed in relation to potential effects on the development of induced cones in the following growth cycle.

Amino acid substitutions preserve protein folding by conserving steric and hydrophobicity properties

We present a comprehensive analysis of amino acid substitution patterns (sets of residues in a position of a multiple alignment) and conservation of physicochemical properties in alignments of protein sequences. Of the one million possible substitution patterns, only a few hundred account for the majority of aligned positions. Very similar distributions of substitution patterns are observed in all but one of the diverse databases of multiple alignments. In these substitution patterns we analyzed the conservation of 511 physicochemical and steric amino acid properties. Highest conservation was observed in those steric and transfer free energy-related properties that are crucial for folding. The best conserved steric properties include the minimal width of the side chains and their interactions with other residues. Among the hydrophobicity-related properties, charge and those properties that provide information on propensities to form secondary structures or side chain conformation, appear to be better conserved than pure hydrophobicity measures. Physicochemical sequence analysis based on the most conserved properties is expected to aid searching a protein sequence query against a database of multiple alignments, prediction of secondary and tertiary structures and protein engineering.

Geometric characterization of stenosed human carotid arteries

RATIONALE AND OBJECTIVES

The geometry of stenosed carotid bifurcations was analyzed to determine average representations for several stenosis grades.

METHODS

Film angiograms of 62 patients with internal carotid artery stenoses were digitized. Residual lumen boundaries were manually outlined. The outlines were processed with a computer to extract geometric measurements. The measurements were grouped according to stenosis grade and used to create average representations.

RESULTS

Accuracy and precision of the outlining technique were +/- 0.020 common carotid diameters (CCD) and +/- 0.025 CCD, respectively. Maximum narrowing of the internal carotid artery occurred at 0.3 CCD +/- 1.5 (mean +/- standard deviation) distal to the flow divider. The region of significant narrowing extended axially 1.2 CCD +/- 1.0. Poststenotic dilatations were observed, with enlargement of 1.3 +/- 0.7 times the normal diameter of the distal internal carotid artery. A tendency toward smaller bifurcation angles with increasing stenosis severity was observed.

CONCLUSION

Three-dimensional geometric models could be created for carotid bifurcations that were disease free (normal) and of arbitrary stenosis grade.

Perspectives: sequence data base searching in the era of large-scale genomic sequencing

Large-scale sequencing of human and model organism genomes will have a profound impact on our ability to use sequence data base searching to predict the biochemical functions of sequences of interest. Despite the great value of more sequences in the data bases, a huge increase in data base size will also have adverse effects on data base searches. Upcoming problems will include (1) greatly increased search times, (2) an increase in background noise of high-scoring but biologically irrelevant matches, (3) inaccurate coding region prediction, leading to problems in protein data base searching, and (4) limited first-pass sequence annotation, making it difficult to determine the biological relevance of data base hits. Improved data base annotation tools and construction of smaller data bases of representative and highly-annotated sequences for first-pass analyses will be essential to deal with the impending flood of new genomic sequence.

Safety of 65 degrees C intravenous fluid for the treatment of hypothermia

BACKGROUND

To demonstrate the safety and efficacy of 65 degrees C (149 degrees F) centrally administered intravenous fluid (CIVF) compared to conventional 40 degrees C (104 degrees F) CIVF in the treatment of hypothermia.

METHOD

Ten beagles (9-13 kg) were prospectively randomized to receive 65 degrees C or 40 degrees C CIVF. They were anesthetized and data were collected at baseline, during hypothermia, and after 1 and 2 hours of rewarming. The plasma free/total hemoglobin (PFHb/THb) was measured to detect hemolysis. Each subject was cooled to 30 degrees C (86 degrees F) and then received either 65 degrees C or 40 degrees C CIVF through a specialized catheter in the superior vena cava for 2 hours in addition to conventional rewarming techniques. All subjects survived 7 days, after which they were sacrificed and a complete autopsy was performed.

RESULTS

The rewarming rate was 3.7 degrees C/hr in the 65 degrees C CIVF group and 1.75 degrees C/hr in the 40 degrees C CIVF group. Core temperatures were significantly different after 1 hour (33.4 degrees +/- 0.77 degrees versus 31.7 degrees +/- 0.57 degrees, P < 0.01) and 2 hours (37 degrees +/- 1.03 degrees versus 33.4 degrees +/- 0.89 degrees, P < 0.001). PFHb/THb was not different. Two intimal injuries occurred in each group but these were remote from the infusion site. Blinded examination by two pathologists could not differentiate the etiology of these injuries from mechanical trauma.

CONCLUSION

CIVF at 65 degrees C is a safe and effective means of treating hypothermia.

FASTA-SWAP and FASTA-PAT: pattern database searches using combinations of aligned amino acids, and a novel scoring theory

We introduce two new pattern database search tools that utilize statistical significance and information theory to improve protein function identification. Both the general pattern scoring theory with the specific matrices introduced here and the low redundancy of pattern databases increase search sensitivity and selectivity. Pattern scoring preferentially rewards matches at conserved positions in a pattern with higher scores than matches at variable positions, and assigns more negative scores to mismatches at conserved positions than to mismatches at variable positions. The theory of pattern scoring can be used to create log-odds pattern scores for patterns derived from any set of multiple alignments. This theoretical framework can be used to adapt existing sequence database search tools to pattern analysis. Our FASTA-SWAP and FASTA-PAT tools are extensions of the FASTA program that search a sequence query against a pattern database. In the first step, FASTA-SWAP searches the diagonals of the query sequence and the library pattern for high-scoring segments, while FASTA-PAT performs an extended version of hashing. In the second step, both methods refine the alignments and the scores using dynamic programming. The tools utilize an extremely compact binary representation of all possible combinations of amino acid residues in aligned positions. Our FASTA-SWAP and FASTA-PAT tools are well suited for functional identification of distant relatives that may be missed by sequence database search methods. FASTA-SWAP and FASTA-PAT searches can be performed using our World-Wide Web Server (http://dot.imgen.bcm.tmc.edu:9331/seq-search/Op tions/fastapat.html).

A comparative transcription map of the murine bare patches (Bpa) and striated (Str) critical regions and human Xq28

The X-linked developmental mouse mutations bare patches (Bpa) and striated (Str) may be homologous to human X-linked dominant chondrodysplasia punctata (CDPX2) and incontinentia pigmenti (IP2), respectively, based on their genetic mapping and clinical phenotypes. Bpa and Str have been localized to an overlapping critical region of 600 kb that demonstrates conserved gene order with loci in human Xq28 between DXS1104 and DXS52. As part of efforts to isolate the genes involved in these disorders, we have begun to develop a comparative transcription map spanning this region in both species. Using techniques of cross-species conservation and hybridization, exon trapping, and cDNA selection we have identified four known genes or members of gene families--caltractin, a member of the gamma-aminobutyric acid (GABAA) receptor gene family, a member of the melanoma antigen gene (MAGE) family, and several members of the murine-specific, X-linked lymphocyte regulated gene (Xlr3) family. Trapped exons and, in some cases, longer cDNAs have been isolated for potentially 7-9 additional genes. One cDNA demonstrates highly significant homology with members of the Krüppel family of zinc finger transcription factors. A second novel cDNA demonstrates homology at the 3' end of the predicted amino acid sequence to a LIM domain consensus. Gene order appears conserved among those cDNAs determined to be present in both human and mouse. Three of the murine transcripts appear to be present in multiple copies within the Bpa/Str critical region and could be associated with a predisposition to genomic rearrangements. Reverse transcriptase PCR (RT-PCR) and Northern analysis demonstrate that several of the transcripts are expressed in mid-gestation murine embryos and neonatal skin, making them candidates for the Bpa and Str mutations and their respective homologous human disorders.

BCM Search Launcher--an integrated interface to molecular biology data base search and analysis services available on the World Wide Web

The BCM Search Launcher is an integrated set of World Wide Web (WWW) pages that organize molecular biology-related search and analysis services available on the WWW by function, and provide a single point of entry for related searches. The Protein Sequence Search Page, for example, provides a single sequence entry form for submitting sequences to WWW servers that offer remote access to a variety of different protein sequence search tools, including BLAST, FASTA, Smith-Waterman, BEAUTY, PROSITE, and BLOCKS searches. Other Launch pages provide access to (1) nucleic acid sequence searches, (2) multiple and pair-wise sequence alignments, (3) gene feature searches, (4) protein secondary structure prediction, and (5) miscellaneous sequence utilities (e.g., six-frame translation). The BCM Search Launcher also provides a mechanism to extend the utility of other WWW services by adding supplementary hypertext links to results returned by remote servers. For example, links to the NCBI's Entrez data base and to the Sequence Retrieval System (SRS) are added to search results returned by the NCBI's WWW BLAST server. These links provide easy access to auxiliary information, such as Medline abstracts, that can be extremely helpful when analyzing BLAST data base hits. For new or infrequent users of sequence data base search tools, we have preset the default search parameters to provide the most informative first-pass sequence analysis possible. We have also developed a batch client interface for Unix and Macintosh computers that allows multiple input sequences to be searched automatically as a background task, with the results returned as individual HTML documents directly to the user's system. The BCM Search Launcher and batch client are available on the WWW at URL http:@gc.bcm.tmc.edu:8088/search-launcher.html.