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Biomedical subjects

W L Gordon

Publications and source records attributed to W L Gordon.

15 recordsLinked to original sources
PubMed1993

Computed tomography for nontraumatic headache: current utilization and cost-effectiveness.

A retrospective study was performed at two teaching hospitals--one in the United States and one in Canada--to determine the results of computed tomography (CT) examinations of the head in patients with nontraumatic headache. Of 1111 examinations performed over a 3-year period, 120 (10.8%) demonstrated an acute intracranial abnormality, such as hemorrhage, infarction or tumour; the frequency of such abnormalities was highest among inpatients and subjects over 40 years of age. Cranial and extracranial abnormalities, such as sinusitis and metastases to the calvarium, were found in 40 (3.6%) of the cases. Chronic abnormalities, such as cerebral atrophy or remote infarction, were the most significant findings in 202 (18.2%) of the cases. The cost of finding each case of acute intracranial abnormality was $5962 (US); for subarachnoid hemorrhage among patients in the emergency department, it was $15,837 (US).

Adolescent↗
PubMed1992

Identification and characterization of a neutralization site within the second variable region of human immunodeficiency virus type 1 gp120.

Two monoclonal antibodies designated BAT085 and G3-136 were raised by immunizing BALB/c mice with gp120 purified from human immunodeficiency virus type 1 (HIV-1) IIIB-infected H9 cell extracts. Among three HIV-1 laboratory isolates (IIIB, MN, and RF), BAT085 neutralized only IIIB infection of CEM-SS cells, whereas G3-136 neutralized both IIIB and RF. These antibodies also neutralized a few primary HIV-1 isolates in the infection of activated human peripheral blood mononuclear cells. In indirect immunofluorescence assays, BAT085 bound to H9 cells infected with IIIB or MN, while G3-136 bound to H9 cells infected with IIIB or RF, but not MN. Using sequence-overlapping synthetic peptides of HIV-1 IIIB gp120, the binding site of BAT085 and G3-136 was mapped to a peptidic segment in the V2 region (amino acid residues 169 to 183). The binding of these antibodies to immobilized gp120 was not inhibited by the antibodies directed to the principal neutralization determinant in the V3 region or to the CD4-binding domain of gp120. In a competition enzyme-linked immunosorbent assay, soluble CD4 inhibited G3-136 but not BAT085 from binding to gp120. Deglycosylation of gp120 by endo-beta-N-acetylglucosaminidase H or reduction of gp120 by dithiothreitol diminished its reactivity with G3-136 but not with BAT085. These results indicate that the V2 region of gp120 contains multiple neutralization determinants recognized by antibodies in both a conformation-dependent and -independent manner.

Amino Acid Sequence↗
PubMed1989

Comparative binding of FSH to chicken and rat testis.

The binding characteristics of two highly purified preparations of follicle-stimulating hormone (FSH), one from equine (e) and one from porcine (p), were compared in a chicken testis radioreceptor assay. A two-component binding model was adequate to explain the binding of eFSH or pFSH to the chicken testis homogenate (CTH) FSH binding sites in the Scatchard study. The affinity of eFSH for the FSH binding site of CTH was 10-fold greater than that of pFSH by Scatchard analysis. This is consistent with the observation that in competitive protein binding studies approximately 10-fold greater quantities of pFSH were required to displace [125I] eFSH from the CTH FSH binding site than eFSH. Qualitatively, the order of relative potencies for various gonadotropin preparations was the same in either the CTH or a rat testis receptor radioligand assay. However, quantitatively, higher potency estimates were obtained with the CTH. The ability of LH preparations to displace radioiodinated pFSH or eFSH from CTH was generally very low with the notable exception of equine LH. The relative potency of highly purified eLH was approximately equal to that of the NIH-FSH-S16 standard (0.906 x NIH-FSH-S16) indicating that in the chicken, as in the rat, (Bousfield and Ward, Biochim. Biophys. Acta 885: 327, 1986), eLH has significant FSH activity. It is concluded that the chicken testis is a convenient and suitable source of FSH receptor (binding sites) for the bioassay of FSH, but that quantitative estimates of potency are not directly comparable when different sources of receptor are used. Finally the data show that eFSH has intriguing structural attributes which provide higher affinity to the chicken testis receptor than pFSH.

Animals↗
PubMed1987

Beta-microseminoprotein (beta-MSP) is not an inhibin.

Beta-microseminoprotein (beta-MSP), a sperm-coating antigen isolated from human seminal plasma, has apparent structural identity with "beta-inhibin" isolated from the same source. Publication of the amino acid sequence of beta-MSP revealed a greater than 96% homology with "beta-inhibin," with only a proline-threonine substitution at positions 39 and 40, and the omission of a glycine at position 93. Due to the nearly identical sequences of "beta-inhibin" and beta-MSP, we examined the ability of beta-MSP and its tryptic peptides to inhibit basal follicle-stimulating hormone (FSH) secretion from rat pituitary cells in culture, the inhibin bioassay. Whole pituitaries collected from 250- to 300-g male rats were dispersed enzymatically and plated onto 24-well culture dishes for 3 days. beta-MSP and its tryptic peptides were dissolved in cell culture medium, applied to the pituitary monolayer cell cultures, and incubated for an additional 3 days. FSH levels in the medium were determined by radioimmunoassay. A partially purified preparation of inhibin and our in-house inhibin standard, both prepared from porcine follicular fluid (pFFl), were included in the same assay. Whereas the partially purified inhibin from pFFl showed a dose-dependent inhibition of FSH secretion, with a 50% inhibitory dose (ID50) of 50 ng, which paralleled that of the standard, beta-MSP and its tryptic peptides failed to depress FSH levels in the medium at any of the doses tested (10-10,000 ng/ml). We conclude that beta-MSP is not an inhibin under our assay conditions.

Animals↗
PubMed1986

Inhibin fractionation: a comparison of human and porcine follicular fluid, with particular reference to protease activation.

A novel treatment has been devised in our studies of the purification of inhibin from porcine and human follicular fluids (pFFl and hFFl, respectively). Both pFFl and hFFl were precipitated with acetone and extracted with acetic acid to provide a starting material for subsequent gel filtration and reverse-phase high-pressure liquid chromatography (HPLC). Inhibin from pFFl was purified 4200-fold using this methodology. Inhibin from hFFl could not be purified to this degree since recoveries were relatively poorer than for pFFl and yielded too little material for the HPLC step. In our fractionation scheme, protease activities were assessed with a gel electrophoresis assay system. Protease activity at approximately 90 kDa was observed in raw pFFl. When inhibin was fractionated by extraction or chromatography, additional bands of protease activity appeared near 150 kDa, 66 kDa and at less than 45 kDa. In raw hFFl, only faint bands of protease activity were observed at approximately 90 kDa and at 85-90 kDa. Upon further fractionation of hFFl, protease activity was reduced below the ability of this method to detect it. Our results suggest that, with our treatment of follicular fluid, protease activity is present in pFFl and additional protease activity appears upon fractionation; proteases, although present, do not eliminate the possibility of obtaining a highly purified inhibin preparation with acceptable recoveries of inhibin activity during purification; and although protease activity could be reduced or eliminated from hFFl, the low yields of inhibin activity from this method mandate a different approach to purification of inhibin from hFFl.

Amino Acid Sequence↗
PubMed1984

Porcine inhibin: initial fractionation as a high molecular weight complex.

A high molecular weight complex or aggregate of inhibition was obtained by chromatography of porcine follicular fluid in Fractogel TSK65F. Recovery of activity was good (usually 80-100%), but only 30-60% was recovered as a high molecular weight complex (greater than 160,000) free of albumin and gamma globulin (the two major proteins in follicular fluid). The balance of the activity was distributed in the gamma globulin-albumin region of the chromatogram (i.e., 160,000 down to 65,000 daltons). Distribution in this region of the chromatogram in part reflected the prior processing of the sample (e.g., it was augmented by ethanol or acetone precipitation prior to chromatography). The utility of Fractogel chromatography lies in its ability to resolve a large portion of the inhibin activity from the major proteins (albumin and gamma globulin), plus an efficient recovery of activity. Maximum purification on the Fractogel chromatograms was approximately 20-fold. This product and the other Fractogel fractions were tested for protease activity by a sensitive slab gel procedure. All fractions contained detectable protease activity that could potentially affect inhibin activity during further fractionations. This was shown with a protease fraction isolated from porcine follicular fluid by affinity chromatography. When added to a partially purified inhibin preparation, this protease fraction destroyed 77% of the inhibin activity.

Animals↗
PubMed1984

Managed reduction of unnecessary skull radiography.

A program to reduce unnecessary skull radiography for trauma was instituted in a teaching hospital in 1970 and eventually proved successful. In 1970, 2 976 skull examinations were made for all purposes and this fell to 791 examinations in 1983. A similar reduction occurred concurrently in the other university teaching hospital departments without the formal program. Only recently has this trend begun in urban hospitals and there is still no change in rural hospitals and urban private radiology offices. The reasons for the decline are attempts to moderate radiation dose, cost containment, clinical use of high yield criteria, and early employment of computed tomography head scanning for trauma. The savings in skull radiography match the related costs of computed tomography with improved patient care.

Adult↗
PubMed1983

Evidence for a role of prostaglandins in the antepartum release of relaxin in the pregnant rat.

The relationship of the antepartum elevation in serum relaxin levels in pregnant rats to luteolysis was examined by determining the effects of the luteolysin prostaglandin F2 alpha (PGF2 alpha) and the prostaglandin synthetase inhibitor indomethacin on antepartum serum relaxin levels, as well as on luteolysis and birth. Intravenous administration of PGF2 alpha on the morning of Day 20 elevated serum relaxin levels approximately fourfold within 15 min. Administration of the prostaglandin synthetase inhibitor indomethacin from Day 19 until Day 23 protracted luteolysis, delayed or prevented birth, and delayed the antepartum elevation of serum relaxin levels, until after indomethacin treatment had been terminated. Collectively, these results indicate that prostaglandins, in particular PGF2 alpha, may promote the antepartum increase in serum relaxin levels, as well as luteolysis and birth in rats.

Animals↗
PubMed1983

Influence of light-dark cycle on antepartum serum relaxin and progesterone immunoactivity levels and on birth in the rat.

Relaxin and progesterone are produced by the corpora lutea in the pregnant rat. Relaxin immunoactivity levels are elevated in peripheral sera during the last 12 days of pregnancy. In rats maintained under a conventional photoperiod of 14 h of light (0600-2000 h) and 10 h of darkness (2000-0600 h), there is an antepartum elevation in serum relaxin to maximal levels coincident with the rapid decline in serum progesterone to basal levels during the light phase of the photoperiod 1 day before birth. Therefore, we postulated that this maximal elevation in serum relaxin levels may be temporally associated with functional luteolysis and linked to the photoperiod. In the present study the photoperiod was advanced near midpregnancy in order to examine further the relationship of the antepartum elevation in serum relaxin levels with both functional luteolysis and the photoperiod. Three groups of rats were maintained under a conventional photoperiod of 14 h of light (0500-1900 h) and 10 h of darkness until days 7 and 8 of pregnancy when the photoperiod was advanced 8 h in group 2 (G2) and advanced 18 h in G3 relative to the conventional photoperiod that was maintained in G1. Serum relaxin and progesterone levels were determined in blood samples obtained at 4-h intervals from 2000 h on day 19 of pregnancy until birth. The times of occurrence of birth, maximal relaxin levels, and decline of progesterone to basal levels in G2 and G3 were generaly advanced 50-60% of the advancement of the photoperiod. There was a close temporal association between the attainment of maximal relaxin levels and basal progesterone levels; they both occurred during the light phase of the photoperiod, approximately 24 h before birth in all three groups. We conclude that the antepartum elevation of serum relaxin to maximal levels may be associated with functional luteolysis and that its time of occurrence is influenced by the photoperiod. This study also provides evidence that the antepartum elevation of relaxin levels consists of two phases which occur at a 24-h interval. It is proposed that these two phases in the elevation of relaxin levels may be indicative of an increasingly effective endogenous circadian luteolytic process whose time of occurrence is influenced by the light-dark schedule.

Animals↗
PubMed1983

Computerized cranial tomography in the evaluation of pituitary tumours in rats.

The use of the rat as an animal model in studies of pituitary tumours has been hampered by the great individual variation and the necessity of killing the animal to assess the development and progression of tumour growth. A study was designed to determine whether computed tomography (CT) could be used to monitor the growth of pituitary tumours in female Sprague-Dawley rats. Animals were injected with oestradiol valerate 2 mg/3 weeks sc, an amount known to lead to development of pituitary tumours (from 45 to 378 mg pituitary weight). Control rats were treated with vehicle alone. Anaesthetized rats injected with contrast were studied by computerized axial tomography and the single CT scans (coronal cuts) were correlated with direct anatomical measurements obtained after pituitary dissection. All pituitaries weighing more than 54 mg were detected by the CT scanner. A good correlation between measurements made after anatomical dissection was found in the two main axes of the coronal cuts. In conclusion, CT scanning can be used for assessment of pituitary tumour size in the rat. This technique should be especially helpful in studies where individual evaluation and/or repeated measurements over time are necessary.

Animals↗
PubMed1980

Radioimmunoassay of relaxin throughout pregnancy and during parturition in the rat.

Relaxin immunoactivaity concentrations in the peripheral sera been measured during pregnancy and parturition in rats with a homologous rat relaxin RIA. Relaxin was not detected until day 10 of pregnancy (day 10). Relaxin levels increased markedly over the next 4 days and generally ranged between 50-100 ng/ml from days 14-20. A prepartum surge in relaxin levels, which appeared to be associated with the photoperiod, occurred on day 21 in unanesthetized rats bled via indwelling jugular cannulas. Mean relaxin levels in these animals increased sharply from less than 80 ng/ml on day 20 to approximately 140 ng/ml at 1400 h on day 21 and declined to less than 60 ng/ml during the 12-24 h preceding parturition. The prepartum surge in relaxin immunoactivity may be associated with luteolysis, since there was an accelerated decline in progesterone concentrations concurrent with the prepartum relaxin surg. Rats also experienced a surge in relaxin concentrations during parturition. The mean maximal level of relaxin during parturition was approximately 180 ng/ml. The rate of decline of rat relaxin immunoactivity levels after bilateral ovariectomy on day 21 demonstrated characteristics of a multiexponential curve. The mean clearance t 1/2 from 0-30 min was 22 +/- 3 min (+/- SEM), and the mean t 1/2 from 30-180 min was 56 +/- 7 min (+/0 SEM).

Animals↗