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Biomedical subjects

V Padmanabhan

Publications and source records attributed to V Padmanabhan.

At least 19 recordsLinked to original sources
PubMed2000

Changes in serum inhibin, activin and follistatin concentrations during puberty in girls.

Serum concentrations of inhibin A, inhibin B, activin A and follistatin were determined using two-site enzyme-linked immunosorbent assays (ELISA) during pubertal ovarian development in 28 girls and five follicular phase women. Blood obtained every 15 to 20 min overnight was pooled for peptide determination. Serum inhibin A concentrations increased in mid puberty, exhibiting positive correlations with bone age (r = 0.527, P = 0.0016) and oestradiol concentrations (r = 0.581, P = 0.0005). Inhibin B concentrations peaked in mid puberty and declined thereafter, but remained greater than concentrations seen in prepubertal girls, and correlating positively with oestradiol (r = 0.362, P = 0.046) and follicle stimulating hormone (FSH) concentrations (r = 0.369, P = 0.038). Total activin A concentrations did not vary significantly across pubertal stages. Total follistatin concentrations, determined by radioimmunoassay, decreased with advancing puberty, exhibiting negative correlations with bone age (r = -0.634, P = 0.0001) and oestradiol concentration (r = -0.687, P = 0.0001). Follistatin concentrations determined by an ELISA specific for follistatin 288 were greatest in mid-pubertal girls, but concentrations in late puberty were less than those in early puberty. The free follistatin assay indicated that all circulating follistatin was activin-bound. These results suggest that significant changes in serum concentrations of FSH-regulatory peptides accompany the onset of puberty.

Activins↗
PubMed2000

Endocrine alterations that underlie endotoxin-induced disruption of the follicular phase in ewes.

Two experiments were conducted to investigate endocrine mechanisms by which the immune/inflammatory stimulus endotoxin disrupts the follicular phase of the estrous cycle of the ewe. In both studies, endotoxin was infused i.v. (300 ng/kg per hour) for 26 h beginning 12 h after withdrawal of progesterone to initiate the follicular phase. Experiment 1 sought to pinpoint which endocrine step or steps in the preovulatory sequence are compromised by endotoxin. In sham-infused controls, estradiol rose progressively from the time of progesterone withdrawal until the LH/FSH surges and estrous behavior, which began approximately 48 h after progesterone withdrawal. Endotoxin interrupted the preovulatory estradiol rise and delayed or blocked the LH/FSH surges and estrus. Experiment 2 tested the hypothesis that endotoxin suppresses the high-frequency LH pulses necessary to stimulate the preovulatory estradiol rise. All 6 controls exhibited high-frequency LH pulses typically associated with the preovulatory estradiol rise. As in the first experiment, endotoxin interrupted the estradiol rise and delayed or blocked the LH/FSH surges and estrus. LH pulse patterns, however, differed among the six endotoxin-treated ewes. Three showed markedly disrupted LH pulses compared to those of controls. The three remaining experimental ewes expressed LH pulses similar to those of controls; yet the estradiol rise and preovulatory LH surge were still disrupted. Our results demonstrate that endotoxin invariably interrupts the preovulatory estradiol rise and delays or blocks the subsequent LH and FSH surges in the ewe. Mechanistically, endotoxin can interfere with the preovulatory sequence of endocrine events via suppression of LH pulsatility, although other processes such as ovarian responsiveness to gonadotropin stimulation appear to be disrupted as well.

Animals↗
PubMed2000

Differential effects of the charge variants of human follicle-stimulating hormone.

FSH is synthesized and secreted by the anterior pituitary gland in multiple molecular forms; the release of these isoforms depends on the endocrine status of the donor at the time of sample collection. In the present study, we analysed the possibility that the FSH charge isoforms may exert differential effects at the target cell. Seven FSH isoform mixes were isolated from pooled anterior pituitary glycoprotein extracts by high resolution chromatofocusing, followed by affinity chromatography, which removed nearly 90% of the LH that co-eluted with the FSH isoforms during chromatofocusing. The isoforms (isoform I, pH >7.10; II, pH range 6.60-6.20; III, pH 5. 47-5.10; IV, pH 5.03-4.60; V, pH 4.76-4.12; VI, pH 4.05-3.82 and VII, pH <3.80) were then tested for their capacity to stimulate cAMP release, androgen aromatization and tissue-type plasminogen activator (tPA) enzyme activity and cytochrome P450 aromatase, tPA and inhibin alpha-subunit mRNA production by rat granulosa cells in culture. cAMP and oestradiol production were determined by RIA, tPA enzyme activity by SDS-PAGE and zymography and all mRNAs by northern blot hybridization analysis and semiquantitative RT-PCR. All isoforms, with the exception of isoform I, stimulated synthesis and release of cAMP, oestrogen and tPA enzyme activity in a dose-dependent manner; the potency of the less acidic isoforms (pH 6. 60-4.60) was greater than that exhibited by the more acidic/sialylated analogs (pH 4.76 to <3.80; potencies II>III>IV>V>VII>VI). A similar trend was observed in terms of cytochrome P450 aromatase and tPA mRNA production. In contrast, when FSH-stimulated production of alpha-inhibin mRNA was analysed, isoforms V-VII were significantly more potent (two- to threefold) than the less acidic/sialylated counterparts (II-IV). In contrast to isoforms II-VII (which behaved as FSH agonists), isoform I (elution pH >7.10) completely blocked P450 aromatase and tPA mRNA expression, without altering that of a constitutively expressed gene (glyceraldehyde-3-phosphate dehydrogenase). These results show for the first time that the naturally occurring human FSH isoforms may exhibit differential or even unique effects at the target cell level.

Analysis of Variance↗
PubMed1999

Automatic measurement of long-term heart rate variability by implanted single-chamber devices.

Heart rate variability (HRV) measurement is an established technology for the assessment of cardiac autonomic status. Recently 24 h HRV has been shown to correlate with disease severity in heart failure. This potentially makes continuous 24 h HRV measurement suitable for monitoring of heart-failure patients. Day-to-day 24 h measurement of HRV is, in principle, feasible when implemented using implanted devices (pacemakers and defibrillators) used in patients who are predominantly in the sinus rhythm. However, a number of such devices used in heart-failure patients are single-chamber devices, in which the distinction between sinus rhythm beats and ectopic beats is problematic. The study investigates whether a reasonably accurate 24 h HRV measurement can be achieved by automatic algorithms, suitable for implementation using implanted devices, without the need for identification of ectopic beats. A set of 5321 nominal 24 h Holter recordings of cardiac patients are used. Each of the recordings contains at least one ectopic beat; approximately 30% of the recordings have more than 1% of ectopic beats. Conventional 24 h measures of HRV, that is the SDNN, HRV index, and SDANN indices, are obtained from each recording after elimination of the ectopic beats and are approximated by HRV measures computed by the same formulas without exclusion of the ectopic beats. The SDANN values are also approximated by the standard deviation of 5 min medians of all RR intervals (SDMRR measure). The errors introduced by including the ectopic beats in the HRV computation were evaluated using the Bland-Altman statistics and by Cohen's kappa statistics investigating the precision of identifying patients with depressed and preserved 24 h HRV. The SDNN measure is very sensitive to the quality of the RR interval sequence and cannot be reasonably used without distinction between sinus rhythm and ectopic beats. The HRV index measure is marginally more acceptable when used without ectopic elimination. The SDANN is rather insensitive, and its replacement by SDMRR values leads to relative errors in the region of 2-5% that are almost independent of the number of ectopic beats included. Even in recordings with a substantial proportion of ectopic beats, a practically acceptable (kappa > 0.9) identification of depressed and preserved SDANN values is possible without ectopic elimination. Thus, continuous monitoring of 24 h HRV is technically feasible within implanted devices, provided the SDANN measure is monitored and either computed from the sequence of all RR intervals or, potentially preferably, replaced by the SDMRR measure.

Defibrillators, Implantable↗
PubMed1999

Follicle-stimulating isohormones: regulation and biological significance.

Follicle-stimulating hormone (FSH) is a key hormone in the regulation of follicular development. Although the existence of FSH heterogeneity is well established, the physiological significance of this pleomorphism remains unknown. Observed changes in circulating FSH heterogeneity during critical reproductive events such as puberty and reproductive cyclicity suggest that different combinations of FSH isoforms reach the target sites during different physiological states to influence a variety of biological end points such as cellular growth, development, steroidogenesis and protein synthesis. Considering that these FSH isoforms have different physicochemical properties and potential to bind not only their cognate receptors but also structurally related, non-FSH receptors with various affinities, the regulatory implications of FSH heterogeneity in modulating the various FSH-induced functions are enormous. However, assigning functional significance to FSH heterogeneity has been hampered because of (1) difficulties associated with procurement of highly purified, naturally occurring, circulating FSH isoforms; (2) absence of reference standards that contain the entire repertoire of FSH isoforms present in biological fluids; and (3) specificity issues inherent to the detection systems used. If particular FSH isoforms do possess selective biological functions, specific combinations of FSH isoforms could be generated to regulate fertility in farm animals and humans.

Animals↗
PubMed1998

Follicle-stimulating hormone is secreted more irregularly than luteinizing hormone in both humans and sheep.

Recently introduced statistical tools capable of discerning differences between the pattern of luteinizing hormone (LH) secretion and that of follicle-stimulating hormone (FSH) could be valuable in understanding ovulation and menopause, and ultimately in making diagnostic decisions and treating infertility and polycystic ovary syndrome. We assessed the validity and scope of the hypothesis that FSH is secreted more irregularly than LH in ewes and fertile women. We compared secretory irregularity of LH to that of FSH in both ovariectomized ewes (n = 7) and women of proven fertility (n = 5) during the follicular and luteal phases of their reproductive cycles. In each sheep, time series from both hypophyseal portal blood (HPB) and peripheral blood were evaluated in 72 samples obtained every 5 min; in each human, both luteal and follicular periods were studied in 192 samples obtained every 7.5 min. To quantify serial irregularity, we used approximate entropy (ApEn), a scale- and model-independent statistic. FSH secretion was consistently more irregular than that of LH in each subject. For sheep HPB, ApEn(FSH) = 1.415+/-0.097 was larger than ApEn(LH) = 0. 822+/-0.213, P < 0.0001 (mean+/-SD, paired t test). This difference persisted peripherally: ApEn(FSHper) = 1.431+/-0.101 > ApEn(LHper) = 1.252+/-0.086, P = 0.024. In women, ApEn(FSH) = 1.467+/-0.217 > ApEn(LH) = 0.923+/- 0.305, P < 0.0001. ApEn(FSH) > ApEn(LH) in 100% of women (peripheral) and sheep HPB. Secretion during the follicular phase was more irregular than during the luteal phase for both FSH and LH (P < 0.01). LH mean level secretion showed a wake/sleep difference in women, P < 0.005, with higher values awake. The consistency and statistical significance of these findings suggest that this LH/FSH difference may be broadly based within higher mammals. Ranges of normative and abnormal regularity values of LH, FSH, and their difference can be used in a number of settings, both (currently) research and (potentially ultimately) clinical milieus.

Animals↗
PubMed1998

Characterization of endocrine events during the periestrous period in sheep after estrous synchronization with controlled internal drug release (CIDR) device.

The Controlled Internal Drug Releasing (CIDR) device is an intravaginal pessary containing progesterone (P4) designed for synchronizing estrus in ruminants. To date, there has been little information available on the timing, duration, and quality of the follicular phase after CIDR removal and how those characteristics compare with natural periovulatory endocrine events. The present communication relates the results of methods we used to characterize the endocrine events that followed CIDR synchronization. Breeding-season ewes were given an injection (10 mg) of Lutalyse (PGF2 alpha), and then studied during three consecutive estrous cycles, beginning in the luteal phase after the estrus induced by PGF2 alpha. Cycle 1 estrus was synchronized with 1 CIDR (Type G) inserted for 8 d beginning 10 d after PGF2 alpha. Cycles 2 and 3 were synchronized with two CIDRs for 8 d beginning 10 d after previous CIDR removal. Cycle 1 estrous behavior and serum gonadotropins showed a follicular phase (the interval from CIDR withdrawal to gonadotropin surge [surge] peak) of 38.2 +/- 1.5 hr. Two CIDRs lengthened the interval to 46.2 +/- 1.5 hr (P < 0.0001). At CIDR removal, circulating P4 concentrations were higher in ewes treated with two CIDRs (5.1 +/- 0.3 and 6.4 +/- 0.4 ng/mL in Cycles 2 and 3 vs. 2.7 +/- 0.3 ng/mL in Cycle 1), whereas estradiol concentrations were higher in the 1 CIDR cycle (3.3 +/- 0.5 pg/mL in Cycle 1 vs. 0.5 +/- 0.1, and 0.7 +/- 0.2 pg/mL in Cycles 2 and 3), suggesting that the lower levels of P4 achieved with one CIDR was not sufficient to arrest follicular development. There were no differences in any other endocrine variable. Both one and two CIDR synchronization concentrated surges within a 24-hr period in 92% of the ewes in Cycles 1 and 2. Cycles 3 ewes were euthanized at estimated luteal, early follicular, late follicular, LH surge, and secondary FSH rise timepoints. Endocrine data and ovaries showed that 88% of the ewes synchronized with two CIDRs were in the predicted stage of the estrous cycle. These data demonstrate that the CIDR device applied during the luteal phase effectively synchronizes estrus and results in a CIDR removal-to-surge interval of similar length to a natural follicular phase.

Animals↗
PubMed1998

Glycoform composition of serum gonadotrophins through the normal menstrual cycle and in the post-menopausal state.

The heterogeneity of follicle stimulating hormone (FSH) and luteinizing hormone (LH) was investigated in five women aged 29.4 +/- 3.2 years (mean +/- SD) throughout their menstrual cycles and in five post-menopausal women aged 53.8 +/- 5.6 years. Chromatofocusing (pH range 7-4) revealed menstrual cycle stage- and postmenopausal-related differences in the serum gonadotrophin charge. There were differences in the proportion of FSH with an isoelectric point (pl) > 4.3 across phases of the menstrual cycle (P = 0.019): midcycle (MC) 50%; early to mid-follicular (EMF) 36%; late follicular (LF) 37%, luteal (L) 29% and following the menopause (PM) 17%. There was no significant difference in the proportion of LH with pl > 6.55 between midcycle (53%) and EMF, LF or L phases (36, 43 and 32% respectively); although all were greater than that found in the menopause (13%). Concanavalin A chromatography revealed less (P < 0.005) complex FSH and LH glycoforms at midcycle (63 and 13%) than in the EMF, LF and L phases (90 and 18; 90 and 20 and 93 and 24% respectively). Menopausal gonadotrophins were least complex (FSH 34%, LH 4%). There was a direct relationship between serum FSH and FSH pl/complexity, and less acidic FSH was associated with reduced FSH complexity. Increased oestradiol was associated with basic FSH isoforms during the menstrual cycle and reduced follicular phase FSH complexity. We conclude that changes in gonadotrophin glycoforms occur through the menstrual cycle which are related to changes in the prevailing steroid environment. Following the menopause oestrogenic loss resulted in acidic, relatively simple glycoforms.

Adult↗
PubMed1998

Resumption of follicular waves in beef cows is not associated with periparturient changes in follicle-stimulating hormone heterogeneity despite major changes in steroid and luteinizing hormone concentrations.

To test the hypothesis that emergence of follicle waves postpartum is associated with a change in circulating FSH isoform distribution, 10 Limousin-cross suckler cows were blood sampled daily from 5 wk prepartum until first ovulation postpartum for FSH, LH, estradiol (E2), and progesterone assay. Follicular growth was monitored daily by ultrasonography from Days 5 to 10 postpartum until first ovulation. Distributions of circulating FSH isoforms were characterized (n = 4 per group) by chromatofocusing at 1) 18-33 days prepartum, 2) 3-5 days prepartum, 3) the first postpartum FSH rise responsible for emergence of the first follicle wave, and 4) the FSH rise that stimulated the ovulatory follicle wave. The interval to detection of the first postpartum dominant follicle (DF) was 9.6 +/- 0.58 days. The number of DF before first ovulation was 2.1 +/- 0.18, and first ovulation occurred at 28.6 +/- 1.54 days postpartum. Serum E2 concentrations were higher (p = 0.0001) in cows during the 5-wk period prepartum (53.8 +/- 6.29 pg/ml) than in the postpartum period up to first ovulation (1.5 +/- 0.15 pg/ml). In late pregnancy, there was an absence of recurrent FSH rises and LH concentrations were decreased (p < 0.0001) compared with those in the postpartum period. The emergence of each follicle wave postpartum was preceded by a 2- to 4-day rise in FSH concentrations. The pattern of FSH isoform distribution did not differ (p > or = 0.75) between the pre- and postpartum periods.

Animals↗
PubMed1998

In pubertal girls, naloxone fails to reverse the suppression of luteinizing hormone secretion by estradiol.

Estradiol (E2) negative feedback on LH secretion was examined in 10 pubertal girls, testing the hypothesis that E2 suppresses LH pulse frequency and amplitude through opioid pathways. At 1000 h, a 32-h saline infusion was given, followed 1 week later by an E2 infusion at 13.8 nmol/m2 x h. During both infusions, four iv boluses of saline were given hourly beginning at 1200 h, and four naloxone iv boluses (0.1 mg/kg each) were given hourly beginning at 1200 h on the following day. Blood was obtained every 15 min for LH determination and every 60 min for E2 determination from 1200 h to the end of the infusion. E2 infusion increased the mean serum E2 concentration from 44+/-17 to 112+/-26 pmol/L (P < 0.01). The mean LH concentration between 2200-1200 h decreased from 3.19+/-0.89 to 1.99+/-0.65 IU/L (P = 0.014), and LH pulse amplitude decreased from 3.4+/-0.6 to 2.6+/-0.5 IU/L (P = 0.0076). Although there were 1.2 fewer pulses during E2 infusion compared to saline infusion, differences did not reach significance (P = 0.1; 95% confidence interval for the difference, -3.5, 1.1). Pituitary responsiveness to GnRH, assessed at the end of the infusion by administering 250 ng/kg GnRH iv, did not change during E2 infusion. The effect of naloxone blockade of opioid activity on LH secretion was determined by assessing the area under the curve (AUC) from 1200-1600 h. During saline infusion, the LH AUC was 1122+/-375 IU/L during saline boluses and 1575+/-403 IU/L during naloxone boluses (P = 0.39). When E2 was infused, the LH AUCs during saline and naloxone boluses were 865+/-249 and 866+/-250 IU/L, respectively. Thus, in pubertal girls: 1) E2 decreases the LH concentration and LH pulse amplitude; 2) the main site of negative feedback effect of E2 appears to be at the level of the hypothalamus; 3) an increase in LH secretion after naloxone administration could not be demonstrated in these girls and may depend on the maturity of the hypothalamic-pituitary-gonadal axis; and 4) opioid receptor blockade does not reverse the E2 inhibition of LH secretion even in the most mature girls. Thus, E2 suppression of LH secretion in pubertal girls appears to be mediated by a decrease in hypothalamic GnRH secretion that is independent of opioid pathways.

Adolescent↗
PubMed1998

A two-site chemiluminescent assay for activin-free follistatin reveals that most follistatin circulating in men and normal cycling women is in an activin-bound state.

Follistatin (FS) is a monomeric protein that binds and regulates the bioavailability of activin. Previously, we found circulating levels of total FS to be similar in men and cycling women. Because relative amounts of activin-bound and free FS are important considerations in determining activin bioavailability, we asked here whether the relative proportions of these two changed during different physiologic states. For this, we developed a two-site, solid-phase, immunochemiluminescent assay for free FS. The assay recognizes the 288 or 315 amino acid variants of human FS and has a detectable limit of 1 ng/mL. Inhibin, transforming growth factor-beta, or alpha-2-macroglobulin do not cross-react or interfere in this assay. Preincubation of FS with activin results in dose-dependent loss of immunoreactivity, confirming specificity of the assay for free FS. Human follicular fluid, pituitary extract, and serum with added FS dilute parallel with the recombinant human FS-288 standard. Recovery of recombinant human FS-288 from serum is quantitative. Using this assay, we found circulating concentrations of free FS to be at or below the detection limit of the assay throughout the menstrual cycle. Comparison of circulating total and free FS levels in postmenopausal or cycling women and normal men suggested that at least 90% is activin-bound. In contrast, measurable quantities of free FS were found in follicular fluid and pituitary extracts. The results of this study, showing that most circulating FS is normally activin-bound, argue against an endocrine role for FS and suggest that a major role of circulating FS is to bind and neutralize the bioactivity of circulating activin. The roles of FS as a local autocrine or paracrine regulator of activin in target tissues, where FS exists in free form, or as an endocrine regulator in human pathophysiology, warrants further investigation.

Activins↗
PubMed1998

Net increase in stimulatory input resulting from a decrease in inhibin B and an increase in activin A may contribute in part to the rise in follicular phase follicle-stimulating hormone of aging cycling women.

Recent studies suggest that an age-related decline in ovarian inhibin B may play a role in the increase in follicular phase FSH in menstrual cycles of older women. Considering that the peripheral feedback regulation of FSH is dictated by the overall tone of inhibins, activins, and follistatins as well as estradiol, it is essential to determine the relative inputs of all of these regulators in assessing whether the collective peripheral input to FSH is one of inhibition or stimulation. To test the hypothesis that changes in the overall tone of peripheral feedback may contribute to this hallmark sign of aging, we compared the concentrations of dimeric inhibin A, inhibin B, activin A, and total and free follistatin in 7 young (mean age, 27.9 +/- 2.6 yr) and 10 older (mean age, 43.6 +/- 0.9 yr) cycling women during the follicular (FOLL; cycle day 6) and midluteal (ML; 7 days post-LH surge) phases of the menstrual cycle. Subjects were preselected on the basis of FOLL phase FSH levels (older, > or = 8.0 mIU/mL; younger, < 8 mIU/mL). Circulating FSH regulatory peptide concentrations were determined from samples pooled from blood drawn every 10 min for 8 daytime h using specific 2-site assays. In the older group, cycle length was shorter (29.1 +/- 0.5 vs. 26.1 +/- 0.5, young vs. older; P < 0.001), mean LH levels during the follicular phase were higher (LH, 5.6 +/- 0.8 vs. 8.8 +/- 1.1 mIU/mL, young vs. older; P < 0.001). Mean FSH levels for the older and younger groups averaged 10.8 +/- 0.8 and 6.2 +/- 0.3 mIU/mL, respectively. Estradiol levels were higher, but not statistically different, than those in the younger group (99 +/- 13 vs. 169 +/- 25 pmol/L, young vs. older; P = 0.06). In both age groups, inhibin B levels were higher in the FOLL vs. ML phase, inhibin A levels were higher in the ML vs. FOLL phase, but total activin A and total and free follistatin did not differ across cycle days. FOLL phase inhibin A levels were higher in the older group (16.3 +/- 2.4 vs. 26.4 +/- 3.4 pg/mL, young vs. older; P = 0.024), but levels of inhibin B were lower (323 +/- 80 vs. 163 +/- 24 pg/mL, young vs. older; P = 0.03). Overall, the estimated total inhibin activity (inhibin A plus inhibin B) was lower in older cycling than in younger women (339 +/- 82 and 189 +/- 24 pg/mL, young vs. older). Total and free follistatin levels were not different among the 2 groups of women. In contrast, total activin A levels were higher in the older cycling group (0.51 +/- 0.05 and 0.68 +/- 0.05 ng/mL, young vs. older; P = 0.02). No differences in age groups were observed during the ML phase for any of the variables measured. These data suggest that a net increase in stimulatory input resulting from a decrease in inhibin B and an increase in activin A may contribute in part to the monotropic FSH increase in aging women.

Activins↗
PubMed1997

Nonclassical secretory dynamics of LH revealed by hypothalamo-hypophyseal portal sampling of sheep.

Continuous withdrawal of hypophyseal portal blood from unrestrained sheep has permitted detailed assessments of the pulsatile secretion of gonadotrophin-releasing hormone (GnRH). To determine if this blood can also be used to characterize the sensory dynamics of pituitary hormones, patterns of luteinizing hormone (LH) in the hypophyseal portal blood of ovariectomized ewes was compared with previous patterns of GnRH and peripheral LH. Hypophyseal portal blood and jugular vein blood were collected every 5 min from six ovariectomized ewes over 6-12 h. Hypophyseal portal blood contained GnRH-associated, sharply defined LH pulses that were much larger than in the periphery. Pulses of secreted LH (hypophyseal portal LH less peripheral LH) showed much faster rates of rise and fall than peripheral and followed pulses of GnRH by an average of 1.26 min. In contrast to pulses in jugular blood, secreted LH pulses often reached a relatively unchanging interpulse nadir-plateau and thereby approached closely algorithm-estimated, extrapolated baselines. The interpulse baseline concentrations of secreted LH (99.6 ng/mL) in hypophyseal portal blood were 31-fold higher than those for jugular LH (3.23 ng/mL). These elevated concentrations also exceeded mean jugular peak concentrations (11.1 ng/mL) and, thus, primarily must represent newly secreted LH. The non-Gaussian profiles of this secreted LH were substantially more complex than the inputs predicted from jugular LH measurements by deconvolution. Furthermore, regardless of the analytical approach, estimations of the mass of secreted LH in each pulse did not correlate well with inputs predicted by deconvolution or Kushler-Brown pulsefit analysis of corresponding pulses in jugular blood (r2 ranging 0.40-0.48). Among alternative explanations is the possibility of heterogeneity in concentrations of GnRH in the portal vessels and variable distribution within the hypophysis. In summary, assay of hypophyseal portal blood obtained directly from the pituitary provides a method for direct assessment of secretory responses to hypothalamic peptides, and thereby serves as an unmatched method for studying the dynamics of LH secretion in vivo. With this approach, LH is revealed to be secreted as complex, non-Gaussian pulses that are far more sharply defined that those in the periphery, include non-GnRH-dependent, secretory components that cannot be predicted by deconvolution and are followed by periods of relatively constant, basal secretion.

Algorithms↗
PubMed1997

Validation of a sensitive radioimmunoassay to measure serum follicle-stimulating hormone in cattle: correlation with biological activity.

Meaningful biological interpretation of the role of follicle-stimulating hormone (FSH) requires use of a validated radioimmunoassay (RIA) that closely estimates biologically active FSH, which was the objective of this work. Three FSH antibodies [NIDDK anti ovine FSH (oFSH); JAD anti oFSH; USDA anti bFSH] were screened against three tracer preparations [USDA oFSH-19-SIAFP-I2(USDA oFSH I2); LER1976a oFSH; USDA bFSH I2] in a RIA using USDA bFSH B1 or I2 as the assay standard. Sera obtained from three heifers at 4- to 8-h intervals for 5 days after injection of PGF2 alpha during the luteal phase were assayed for both FSH immunoactivity using each of the three optimized assay formats (NIDDK anti oFSH and JAD anti oFSH with USDA oFSH I2 as tracer; USDA anti bFSH with USDA bFSH I2 as tracer), and FSH bioactivity, using a rat Sertoli cell bioassay. Cross reactivity of bLH (NIH bLH B9) in all three assay formats was minimal (0.7, 0.9 and < 0.4% at 50% binding for the NIDDK, JAD and USDA antibodies, respectively). There was parallel displacement of tracer between bovine serum dilutions of 10 to 500 microliters and the two FSH standards. Correlations between JAD and USDA RIA data and bioassay results were not significant (P > or = 0.10), but were significant (r = 0.78; P = 0.0001) for the NIDDK RIA FSH and the bioactive FSH measurements. The assay sensitivity of the NIDDK RIA was 0.55 ng USDA bFSH B1 (0.013 ng USDA bFSH I2)/ml. The inter- and intra-assay CV were between 5.8 and 7.9 %. This RIA detected a pre-ovulatory FSH surge coincident with the LH surge, in all heifers studied. Furthermore, the emergence of each wave of follicle growth (up to day 12 of the cycle), was preceded by a transient increase (P < 0.02; days 0.5 to 1.5 and 8 to 10.5 of the cycle) in serum FSH, while LH concentrations remained unchanged. In conclusion, the RIA utilising NIDDK anti oFSH and USDA oFSH I2 as tracer provides a good estimate of bioactive FSH in cattle, and detects physiologically relevant increases in serum FSH related to emergency of each new wave of follicle growth.

Animals↗
PubMed1997

Expression analysis of a gene family in loblolly pine (Pinus taeda L.) induced by water deficit stress.

A cDNA clone (lp3) from loblolly pine induced by water deficit stress (WDS) has been isolated. It is preferentially induced in roots with a constitutive basal level of expression also observed in stems and needles. Northern blot analysis with well irrigated ABA-treated seedlings indicated that the overall accumulation of lp3 transcripts in the roots was lower than that of water deficit-stressed seedlings. However, within roots, lp3 was induced by ABA indicating that the expression of lp3 in roots under WDS conditions was partly mediated by ABA. The lp3 clone is similar to a group of genes called asr (ABA stress and ripening) genes identified in several species. A genomic clone (lp3-1) was identified and its putative protein has the hydrophylicity profile similar to that of lp3 except for two deletions in the 5' region. The genomic Southern and RT-PCR (reverse transcriptase-polymerase chain reaction) analyses indicate that the lp3 gene belongs to a small multigene family of at least four members with a distinct pattern of expression during WDS.

Amino Acid Sequence↗
PubMed1997

Phyllodes tumor with lobular carcinoma in situ and liposarcomatous stroma.

We describe a patient with a malignant phyllodes tumor with both lobular carcinoma in situ and liposarcomatous stromal differentiation. Although lobular carcinoma in situ and adipose differentiation have been reported as separate features rarely seen in the phyllodes tumor, we are unaware of any cases in which both of these features have been seen within the same tumor. The prognosis for this patient related not only to the malignant stromal component of the tumor but also to her increased risk of developing carcinoma in the remaining breast tissue.

Biomarkers↗
PubMed1997

Prevention of hypertension during trans-sphenoidal surgery--the effect of bilateral maxillary nerve block with local anaesthetics.

BACKGROUND: Severe cardiovascular responses are known to occur during trans-sphenoidal excision of the pituitary gland despite adequate depth of anaesthesia. This study was undertaken to evaluate the effects of bilateral maxillary nerve block with local anaesthetics on the cardiovascular responses to various stimuli during this procedure. METHODS: In a group of 32 patients, 5-10 ml of a mixture of bupivacaine 0.5% and lignocaine 2% (1:1) was injected in the pterygopalatine fossa after induction of general anaesthesia. Seven control group patients did not receive any nerve block. In all the patients, general anaesthesia was induced with thiopentone and maintained with nitrous oxide-oxygen, pentazocine, boluses of thiopentone and halothane. Pancuronium was used for neuromuscular blockade. RESULTS: In both the groups, maximum hypertension occurred on opening the blades of the bivalve nasal speculum. In the study group, hypertensive response was significantly less following nasal infiltration with adrenaline containing solution (10.26% increase vs. 23.08% in the control group, P < 0.05), nasal dissection (2.82% vs. 9.45%, P < 0.01) and on application of the nasal speculum (14.93% vs. 35.16%, P < 0.01). The effect on heart rate response was not significant. CONCLUSION: The described technique is a useful adjunct to general anaesthesia for suppressing the haemodynamic responses during trans-sphenoidal surgery.

Adult↗