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Biomedical subjects

D J Phillips

Publications and source records attributed to D J Phillips.

At least 73 records · Page 4Linked to original sources
PubMed1994

Serum gonadotropin isoforms become more basic after an exogenous challenge of gonadotropin-releasing hormone in children undergoing pubertal development.

Recent clinical studies have questioned whether there is a qualitative change in the circulating isoforms of LH and FSH after stimulation by GnRH. The present study investigated the median charge of serum gonadotropin isoforms before and after an exogenous challenge of 100 micrograms GnRH in 10 girls and 10 boys undergoing pubertal development. All of the children had basal serum levels of LH and FSH and responses 30 and 60 min after GnRH treatment that were considered normal for puberty. LH and FSH in serum and eluates after electrophoresis in 0.10% agarose suspension were measured with sandwich fluoroimmunoassays. The increases in serum gonadotropin concentrations were generally similar for both sexes, but girls had significantly (P < 0.05) higher LH levels at 30 and 60 min than boys and a larger (P < 0.05) relative increase in serum FSH levels after GnRH treatment. In terms of the median charge of serum isoforms, the girls had significantly less negative (i.e. more basic) isoforms of LH (P < 0.05) and FSH (P < 0.001) than the boys. There was a change to more basic isoforms of both LH and FSH in all children 30 min after GnRH administration. For LH, the charge had returned to pretreatment values by 90 min after GnRH, but for FSH, the charge was still significantly (P < 0.05) more basic at this time (n = 4/sex). When the LH isoforms were more acidic before GnRH treatment, the change in median charge was larger than when the isoforms were more basic beforehand. A similar relationship was not found for FSH. Conversely, there was for FSH, but not for LH, a significant (P < 0.001) relationship between the relative increase in serum concentrations and the change in charge of the isoforms 60 min after GnRH treatment. These findings show that the circulating forms of LH and FSH become more basic after an exogenous challenge of GnRH in children undergoing pubertal development and suggest that the differences in the responses of LH and FSH isoforms may be due to differing degrees of selective secretion and/or survival.

Adolescent↗
PubMed1994

Femur fractures with femoral or popliteal artery injuries in blunt trauma.

The treatment and results of 13 blunt femoral fractures with an arterial injury were reviewed. Two of the 13 patients (15%) sustained segmental (two levels) arterial injuries. Stabilization of the femur fractures were performed before arterial repair in 10 of the 13 femurs. The results were determined at an average of 4.5 years. For the eight open fractures, two patients had above-knee amputations, no limb regained > 90 degrees of knee motion, four patients required a brace or cane, and three patients have intermittent wound drainage. The five closed fractures all regained full function with full knee motion. Due to the 15% incidence of segmental arterial injury, "wide-field" arteriography is advised for the evaluation of this injury. Femoral stabilization may be performed before arterial repair if the procedure does not encroach on the viability of the limb. The functional results depend on the soft-tissue damage, as illustrated by the poor results seen in open fractures.

Adolescent↗
PubMed1993

Differential patterns of dynamic cardiovascular regulation as a function of task.

In cardiovascular reactivity studies, interpretations of the processes supporting the blood pressure response may become problematic when systolic blood pressure, diastolic blood pressure, and heart rate all increase in response to a behavioral challenge. Therefore, in addition to evaluating these cardiovascular responses, this study examined cardiac output, total peripheral resistance and systolic time intervals derived from impedance cardiogram, electrocardiogram and phonocardiogram recordings during a speech stressor, a mirror tracing task, and a foot cold pressor test. All of the behavioral stressors elicited increases in blood pressure and heart rate, with the largest changes occurring during the overt speech. Based on the examination of the response patterns of the underlying hemodynamic variables it would appear that, in both men and women, the blood pressure increase during the speech preparation period was supported by increased cardiac output; the speech itself resulted in a mixed pattern of increased cardiac output and total peripheral resistance; whereas, the mirror tracing and cold pressor tasks produced increased total peripheral resistance. Although men and women produced similar response patterns to the behavioral challenges, sex differences in the estimates of myocardial contractility were observed during rest. These results provide evidence that different behavioral stressors can produce a distinct yet integrated pattern of responses, whose differences may be revealed, when impedance cardiography is used, to derive sufficient response measures for assessing dynamic cardiovascular processes.

Adult↗
PubMed1993

Biopotency in vitro and metabolic clearance rates of five pituitary preparations of follicle stimulating hormone.

Five pituitary preparations of follicle stimulating hormone (FSH), namely NIDDK-oFSH-17, Bioscan oFSH, Ovagen, Folltropin-V and F.S.H.-P., were examined for biological activity in terms of their potency in an in vitro bioassay, receptor assay and heterologous radioimmunoassay and in terms of their metabolic clearance rates. In the three assays, Bioscan oFSH was the most potent (P < 0.05) (3- to 5-fold the potency of NIDDK-oFSH-17), with Ovagen being 25-50% the potency of the NIDDK standard (P < 0.05). Folltropin-V and F.S.H.-P. had the lowest potencies in all three assays. For each preparation, the ratio of activities between the assays was not consistent, suggesting that the preparations behaved differently in each assay. In 9 of 10 cases, potency estimates in the heterologous radioimmunoassay were greater than those in the in vitro bioassay or receptor assay. Polyacrylamide gel electrophoresis of the preparations showed banding consistent with the molecular weight of FSH, but also indicated that the preparations were contaminated with other proteins to varying extents. The half-lives of these preparations when injected into the bloodstream of mature female mice were 28.0, 8.6, 13.4, 11.6 and 17.4 min for NIDDK-oFSH-17, Bioscan oFSH, Ovagen, Folltropin-V and F.S.H.-P. respectively. The slopes of the decay rates were significantly different from each other (P < 0.05) except between Ovagen and Folltropin-V. The results of these studies show that a number of widely available FSH preparations have differing biopotencies. Moreover, the biopotency of a preparation in vitro is not related to its metabolic clearance rate, and not all FSH preparations behave identically in different assays. Measures of biopotency in vitro combined with those of metabolic clearance rate may provide useful information on the properties of FSH preparations used for research purposes and for superovulation of farmed livestock.

Animals↗
PubMed1993

Ovaries of ewes homozygous for the X-linked Inverdale gene (FecXI) are devoid of secondary and tertiary follicles but contain many abnormal structures.

Ewes homozygous (II) for the Inverdale prolificacy gene (FecXI) located on the X chromosome are infertile with "streak" ovaries. The aims of this study were to examine the ovarian morphology and plasma and tissue (or extracellular fluid) hormone concentrations in II ewes in comparison to control (++) animals. All II animals (n = 11) were found to contain no normal ovarian follicles beyond the primary stage of development despite their being similar in number of germ cells to the ++ ewes. The II animals had high plasma gonadotropin levels and undetectable estradiol and progesterone, and in addition 6 of 9 ewes had undetectable plasma inhibin concentrations. II ewes contained large numbers of oocyte-free follicles ("nodules") that were often found as clusters in the innermost regions of the cortex. In addition, 6 of 11 ewes contained abnormal luteal- or granulosa cell-like structures and other unusual formations. In three II animals the abnormal structures were visible on the ovarian surface, and the plasma inhibin concentrations in these ewes were significantly higher than in the ++ ewes (p < 0.05). Collectively these findings suggest that two copies of the FecXI mutation impair the resumption of growth of primordial follicles and may in some instances lead to the development of abnormal structures having a morphology consistent with that observed for ovarian tumors.

Animals↗
PubMed1993

Short-term regulation of gonadotropin subunit mRNA levels by estrogen: studies in the hypothalamo-pituitary intact and hypothalamo-pituitary disconnected ewe.

In this study the levels of mRNA for the pituitary gonadotropin hormone subunits luteinizing hormone beta (LHbeta), follicle stimulating hormone beta (FSHbeta) and the common alpha-subunit were assessed during the acute feedback stages of estradiol benzoate (EB) action in ovariectomized (OVX) ewes with and without hypothalamo-pituitary disconnection (HPD). In OVX/HPD ewes maintained on hourly pulses of 250 micrograms of gonadotropin-releasing hormone (GnRH) a single i.m. injection of EB in oil caused a biphasic (decrease and then increase) change in plasma LH levels and a monophasic decrease in FSH levels. There was a decrease in pituitary alpha-subunit and FSHbeta mRNA levels during the acute negative (8 h post EB) and through the positive feedback (20 h post EB) stages of the response. No significant change was seen in LHbeta mRNA levels following treatment with EB. In hypothalamic-pituitary intact OVX ewes the same EB treatment as above caused a biphasic change in LH secretion with the positive feedback component being much greater than in GnRH-pulsed OVX-HPD ewes. The levels of mRNA for all three gonadotropin subunits were reduced by 8 h after EB injections and remained low throughout the positive feedback period. These data suggest that the LH surge in this experimental model does not require an increase in LHB mRNA levels. Furthermore, the fall in LHbeta subunit mRNA seen after estrogen injection of OVX ewes is most likely due to an effect of estrogen to decrease GnRH secretion, since pulsatile GnRH replacement prevents this effect. These data also show that estrogen feedback can effect rapid alterations in pituitary gonadotropin subunit mRNA levels. Short-term changes in FSHbeta mRNA are reflected in changes in FSH secretion; the same is not true for LH.

Animals↗
PubMed1993

Protein S, an antithrombotic factor, is synthesized and released by neural tumor cells.

Protein S, an anticoagulant factor in the protein C antithrombotic pathway, was found to be synthesized and released by six tumor cell lines of neural origin by western blotting and ELISA. The rate of synthesis ranged from three- to 11-fold higher than that of a microvascular endothelial cell line and 36-144% that of a hepatoma cell line. The secreted protein S displayed specific anticoagulant activity similar to that of purified plasma protein S, implying that it was fully gamma-carboxylated. Ten primary brain tumor tissues also expressed protein S antigen, as shown by western blot analysis. Expression of anticoagulantly active protein S by neural cells raises important questions concerning possible physiologic roles for this multidomain protein beyond its function in control of thrombosis.

Blotting, Western↗
PubMed1993

Effects of the Booroola gene (FecB) on body weight, ovarian development and hormone concentrations during fetal life.

The aim of this study was to determine whether the FecB gene influenced some aspects of fetal development in sheep. Carrier (BB/B+) and non-carrier (++) female fetuses were recovered at specific times of gestation, namely, days 40, 55, 75, 90, 95 and 135. The results showed that the FecB gene influenced litter size, body weight and ovarian development during fetal life. The mean litter sizes were larger (P < 0.05) and body weights were lighter (P < 0.05) at most gestational ages in BB/B+ than in ++ fetuses. Morphometric studies of the ovary showed that the development of the BB/B+ ovaries was retarded: the ++ genotype had more oogonia at day 40 (P < 0.01), more germ cells entering meiosis at day 55, more primordial follicles developing at days 75, 90 and 95 (P < 0.05), a greater loss of germ cells by atresia at day 90 (P < 0.01) and more growing follicles (P < 0.01) and more antral follicles (P < 0.05) at day 135. Differences between the BB/B+ and ++ genotypes in the plasma concentrations of immunoreactive (i) inhibin, i-FSH, bioactive (b)-FSH or (i)-LH were not apparent at any age except for i-LH at day 75 (BB/B+ > ++; P < 0.05). Likewise no differences were noted in the contents of ovarian or adrenal oestradiol or i-inhibin except for i-inhibin in the adrenal at day 75 (++ > BB/B+, P < 0.01). No differences between the genotypes were noted in the i-inhibin contents of the mesonephros at day 40. In mid- to late but not early gestation (i.e. days 40 and 55) significant correlations (i.e. P < 0.05) were noted between litter size and body weight at days 75, 90 and 135, and between litter size and ovary weight, ovary volume, adrenal weight and pituitary weight at day 135. To eliminate the effect of litter size, equal numbers of BB/B+ and ++ embryos were transferred to respective recipient ewes, and fetuses were recovered at the equivalent of days 40 and 90 of gestation. The results showed that the genotypic difference in fetal body weight at day 40 (++ > BB, P < 0.001) and in number of oogonia at day 90 (++ > BB/B+, P < 0.05) were independent of litter size.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Gonadotrophin-releasing hormone and the control of ovulation rate by the FecB gene in Booroola ewes.

Booroola sheep carry a FecB gene that confers high fecundity. The aims of the present studies were to determine in homozygous carriers (BB) and non-carriers (++) of the Booroola FecB gene whether there are FecB differences in the secretory characteristics of GnRH in hypophyseal-portal blood of ovariectomized ewes (Expt 1) and whether differences in ovulation rate would occur following the administration of PMSG and pulsatile GnRH to ovary-intact Booroola ewes with hypothalamic-pituitary disconnection (HPD) (Expt 2). In Expt 1, no FecB gene-specific differences were noted for GnRH with respect to pulse frequency, pulse amplitude or overall secretion rate. Irrespective of genotype there were 1.9 +/- 0.2 GnRH pulses h-1 (n = 20 ewes; 10 BB and 10 ++ animals) and 1.9 +/- 0.1 pulses of immunoreactive (i) LH h-1. In Expt 2, ovulation was induced in the HPD ovary-intact animals on three occasions (e.g. 56, 393 and 423 days after HPD surgery) using a PMSG (200 or 400 iu)-GnRH pulse (250 ng i.v. for 96 h)-GnRH bolus (10 micrograms i.v.) regimen after pretreating the animals with GnRH pulses (250 ng i.v. for 14 days). On all occasions the ovulation rates were significantly higher (P < 0.05) in BB ewes (n = 6 or 7) than in ++ animals (n = 7). No differences between the genotypes were noted with respect to the mean concentrations of progesterone in plasma notwithstanding the differences in ovulation rates.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Effects of ovariectomy and genotype on bioactive FSH in plasma and pituitary of Booroola ewes.

Blood samples were collected for 13 days before and 20 days after ovariectomy from carrier (BB) and non-carrier (+ +) ewes of the Booroola FecB gene (n = 12 per genotype), at known stages of the oestrous cycle, after which the pituitary glands from these ewes were recovered. Pituitary glands were also collected from cyclic ewes (about day 12; n = 5 per genotype) to compare the effects of ovariectomy on pituitary gonadotrophins. Plasma samples and pituitary extracts were assayed for bioactive (B) FSH, immunoreactive (I) FSH and I-LH. Overall, BB ewes had significantly (P < 0.05) higher plasma I-FSH concentrations than did + + ewes before ovariectomy; the mean value was higher on 16 of the 17 days of the oestrous cycle (P < 0.01). For B-FSH, there were no overall genotypic differences, although the mean for the BB ewes was significantly higher on 13 of the 17 days of the oestrous cycle (P < 0.05), and significantly (P < 0.05) higher between days 13 and 16. No genotypic differences were noted for the plasma bioactive:immunoreactive (B:I) ratio for FSH before ovariectomy. After ovariectomy, there were significant (P < 0.001) increases in plasma for B-FSH, I-FSH and I-LH and a significant (P < 0.05) decrease in the B:I ratio for FSH, irrespective of genotype.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Evaluation of monoclonal antibodies having specificity for human IgG subclasses: results of the 2nd IUIS/WHO collaborative study.

Following the 1st IUIS/WHO Collaborative Study of monoclonal anti-IgG subclass antibodies, a panel of WHO Specificity Reference Reagents (SRR) was established [Jefferis, R., et al. (1985) Immunol. Lett., 10, 223]. At the time, the hope was expressed that further reagents particularly for IgG2, and other allotypic specificities would become available which could be applied in a wide range of assay protocols. The 2nd study reports the evaluation of nineteen anti-subclass and seven anti-allotype monoclonal antibodies. The anti-IgG1 antibody HP6187 was equivalent in performance to the SRR. Others, that were not of the mouse IgG1 isotype, may be useful for particular applications. The anti-IgG2 antibody HP6200 could be a valuable addition to the WHO SRR; it is specific for an epitope in the Fab region but does not have the light chain bias of HP6014. Antibodies of putative allotype specificity exhibited the claimed specificity when used within protocols similar to those employed by the originating laboratory. It appears to be inherent in the nature of the epitopes (allotopes) recognized that it will take several years before reagents applicable to a wide range of techniques will become available.

Antibodies, Anti-Idiotypic↗
PubMed1992

Flow separation in the carotid bulb: prognostic significance.

It has been previously shown that boundary layer or flow separation occurring in the carotid bulb and detected by duplex scanning denotes minimal or no carotid atherosclerotic disease as demonstrated by angiography and reliably predicts aetiology other than carotid artery disease in symptomatic patients. To evaluate outcome at long-term follow-up we prospectively studied 94 patients (48 males, 46 females) who demonstrated bilateral flow separation. Mean age was 61.2 years (27 to 86 years). Mean follow-up was 57 months (5 to 113 months). There was one death during follow-up at 69 months. It was stroke related. Using age and sex specific death rates for the general population 14.3 deaths would be expected for the same average period. By life table analysis, survival was 98.7% at five years compared to a general population expected 5 year survival of 85.9%. There were no strokes at 5 years of follow-up. (Age and sex specific stroke-free survival for Rochester, MN 1970-1974 is 98% at 5 years). TIA-free survival was 99% at one year (n = 87) and 96% at five years (n = 46). It is concluded that the presence of boundary layer separation in the carotid bulb not only indicates absent or minimal atherosclerotic disease, but is predictive of a favourable long-term outcome with respect to mortality and neurological events.

Age Factors↗
PubMed1992

PCR regimen for enhanced specificity and yield of targeted genomic DNA sequences: ras and p53.

By weighting the PCR reaction in favor of specificity for the target sequence in the beginning cycles and for continued efficient amplification of the sequence into later cycles, we were able to show an improvement in the specificity and quantity of amplified ras and p53 sequences. Increased purity and yield of specific products favorably enhanced post-PCR evaluation and interpretation of results using direct sequencing and single-stranded conformation polymorphism (SSCP) analysis when point mutations were present in DNA from tumor cell lines and tissues.

Base Sequence↗
PubMed1992

Bioactive and immunoreactive FSH and immunoreactive inhibin concentrations in the ovine fetus.

The bioactive (B) and immunoreactive (I) pituitary contents/concentrations of FSH, together with the plasma concentrations of B-FSH, I-FSH and I-inhibin were determined in ovine fetuses at days 55, 75, 90 and 135 of gestation (day 145 = term). The pituitary contents and concentrations of B-FSH and I-FSH increased in both sexes with gestational age. The female fetuses had significantly (P < 0.01) higher pituitary contents/concentrations of B-FSH and I-FSH than the male fetuses at days 75 and 135. The pituitary B/I ratios of FSH were not significantly different with age or sex. The plasma concentrations of B-FSH remained relatively constant from days 75 to 135, with no significant differences between sexes or with age. In contrast, the plasma concentrations of I-FSH reached a peak at day 90 and then declined towards term in both sexes. At all gestational ages except day 55, the female fetuses had significantly (P < 0.05) higher plasma concentrations of I-FSH than the males. In both sexes, the plasma B/I ratios of FSH were lowest at day 90 and had increased again by day 135, with the male fetuses having significantly (P < 0.05) higher B/I ratios compared with the female group at days 75 and 135 but not at day 90. At all gestational ages, the plasma concentrations of I-inhibin declined throughout gestation in the female fetuses, whereas in the males they reached a nadir at day 75 and then increased towards term. The concentrations of I-inhibin were significantly (P < 0.01) higher in the male fetuses compared with the females.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

A triangulation method for the quantitative measurement of arterial blood velocity magnitude and direction in humans.

A triangulation method has been applied to a duplex ultrasound scanner to quantify blood flow velocities in two dimensions. A position locating system (PLS) connected to the scanhead locates the sample volume (SV) in 3-D space to a precision of 1 mm. The PLS is used to obtain flow velocity data from two independent lines of sight in the human femoral artery. Data are gathered from anatomic sites of interest along one line of sight. Later the computer directs the SV to interrogate the same points in space from a second line of sight. Water tank studies using both constant velocity and pulsatile string targets were used to validate the method. Velocity magnitudes could be calculated to within 5% error for Doppler angles below 75 degrees for various string depths and speeds; the error in Doppler angle calculation was usually less than 3 degrees. Results from the superficial femoral artery show flow velocity vectors are nearly parallel to the vessel walls. Peak systolic velocity magnitudes range from 63-66 cm/s in three presumed normal individuals. Following the validation studies addressed in this paper, this triangulation approach is intended in future work to document the complex nonaxial character of blood flow that occurs normally at branch points and in regions of intraluminal disease.

Blood Flow Velocity↗
PubMed1990

Effects of the synthetic glucocorticoid dexamethasone on reproductive function in the ewe.

Glucocorticoids have been found to inhibit reproductive function in most domestic species studied but, in the ewe, preliminary reports suggest that glucocorticoids may have little or no effect. This study investigated the effects of the synthetic glucocorticoid dexamethasone on oestrus and ovulation rate in ewes during the breeding season and gonadotrophin secretion in the breeding and non-breeding seasons. In cyclic ewes, dexamethasone treatment at rates of up to 2 mg/day did not affect the natural or pregnant mare serum gonadotrophin-stimulated ovulation rate, or the timing and incidence of behavioural oestrus (P greater than 0.05). Dexamethasone administration (2 mg/day) had no effect on LH secretion or the plasma LH response to a 1 micrograms injection of gonadotrophin-releasing hormone (GnRH) in ovariectomized ewes in the breeding and non-breeding seasons, and did not compromise the inhibition of plasma LH levels during chronic treatment with oestrogen. Similarly, dexamethasone had no effect on plasma FSH concentrations, but significantly (P less than 0.05) reduced the plasma FSH response to a 1 micrograms GnRH injection during chronic negative treatment with oestrogen in ovariectomized ewes. Collectively, these data show that in these experiments dexamethasone did not significantly modify reproductive function in the ewe, a finding that is in contrast to that found in other domestic species.

Animals↗