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S D Holmes

Publications and source records attributed to S D Holmes.

At least 37 records · Page 2Linked to original sources
PubMed1985

Fasciola hepatica: motility response to metabolic inhibitors in vitro.

The effects of metabolic inhibitors on the in vitro motility of Fasciola hepatica have been determined by means of an isometric transducer system. Sodium fluoride, an inhibitor of glycolysis, causes a long-term suppression of motility; this is also the effect of sodium iodoacetate (another glycolysis inhibitor) at low concentrations (1 X 10(-5) M and below). However, higher concentrations of iodoacetate induce a rapid inhibition of activity leading to a spastic paralysis. Both rotenone and oligomycin, which act as inhibitors of oxidative phosphorylation, produce a long-term suppression of movement. Carbonylcyanide-p-trifluoromethoxyphenylhydrazone and carbonylcyanide-m-chlorophenylhydrazone, which are uncouplers of oxidative phosphorylation, induce a spastic paralysis of the fluke; this is rapid at high concentrations (1 X 10(-4) and 1 X 10(-5) M). A brief stimulation of activity is evident at 1 X 10(-5) M and lasts longer at 1 X 10(-6) and 1 X 10(-7) M, before inhibition sets in. There is no stimulation at low concentrations of carbonyl cyanide-p-trifluoromethoxyphenylhydrazone (1 X 10(-8) and 1 X 10(-9) M), only inhibition leading to a medium-term spastic paralysis. In contrast, a third uncoupler, 2,4-dinitrophenol, causes a flaccid paralysis and the effect is rapid only at high concentrations, being accompanied by an initial increase in muscle tone at 1 X 10(-2) M and a brief stimulation of motility at 1 X 10(-3) M. Stimulation lasts longer at 1 X 10(-4) and 1 X 10(-5) M, but is not evident at concentrations below this. The effects on motility at these lower concentrations are essentially long term in nature. That the rapid effects of the uncouplers on muscle tone and motility are not due primarily to uncoupling is shown by 2,4,6-trinitrophenol and hydroquinone, compounds structurally related to 2,4-dinitrophenol. 2,4,6-Trinitrophenol is a membrane-impermeable compound devoid of uncoupling activity; at 1 X 10(-3) M, it causes an immediate inhibition of activity and increase in muscle tone. The antioxidant hydroquinone produces an initial stimulation of motility with some increase in tone, but this is followed by a sharp decline and a short-term flaccid paralysis. The results are discussed in relation to the postulated effects of certain fasciolicides on the energy metabolism of the liver fluke.

2,4-Dinitrophenol↗
PubMed1985

Ion exchange, chromatofocusing and size exclusion high-performance liquid chromatography of the human uterine progesterone receptor.

The human uterine progesterone receptor was subjected to high-performance liquid chromatography on size exclusion, anion exchange and chromatofocusing columns. For the rapid isolation of the receptor, recovery of [3H]progesterone as well as protein from the columns was essential. The size exclusion columns (G2000 SW and G3000 SW) as well as Mono P HR 5/20 chromatofocusing column adsorbed [3H]progesterone and thus were not useful for separation purposes. The anion exchange (polyanion SI-17) and chromatofocusing columns, AX500, and IEX 540 DEAE gave very good recoveries of protein (greater than 90%) and [3H]progesterone; 80, 66 and 88% respectively. These columns gave rapid and reproducible separation of the progesterone receptor from other cytosol proteins.

Affinity Labels↗
PubMed1985

Rapid method for quantitation of androgen binding protein in Sertoli cell cultures and its use for measurement of binding kinetics.

The accurate measurement of the kinetics of binding of 5 alpha-dihydrotestosterone to the Sertoli cell specific protein, androgen binding protein (ABP), has been frustrated by the extremely rapid rate of dissociation of the ABP-dihydrotestosterone complex. We describe a rapid and highly sensitive assay suitable for ABP quantitation which utilizes DEAE Bio-Gel and [3H]dihydrotestosterone. The assay has been used to accurately measure the rate of dissociation (8.25 X 10(-4) s-1, t1/2 14 min) and the rate of association (2.04 X 10(5) M s-1) of the binding of [3H]dihydrotestosterone to rat ABP. The ratio of these rate constants is in perfect agreement with the equilibrium dissociation constant determined by Scatchard analysis (4.0 nM). This multipoint assay is extremely rapid such that binding can be measured at equilibrium, it has high precision (coefficient of variation 3%), and is particularly useful at low protein concentrations (50 ng/ml); furthermore, the assay background of nonspecific 3H-binding is extremely low (0.2%). Since at such low protein concentrations a 10 point Scatchard analysis can be performed on 1 ml culture medium containing as little as 3 fmol ABP, the assay is suitable for monitoring changes in ABP secretion resulting from manipulations of cells in culture. The assay which utilizes DEAE Bio-Gel A is compared to five alternative methods: the standard method of steady state gel electrophoresis, Dextran-coated charcoal assay, hydroxylapatite assay, DEAE filter assay, and radioimmunoassay. The DEAE Bio-Gel assay has advantages over all of these alternative methods. In summary, this new assay is particularly useful for monitoring temporal changes in the secretion of ABP, and the method is equally effective in quantitating ABP in rat, rabbit and hamster Sertoli cell cultures.

Adsorption↗
PubMed1985

Peritoneal fluid plasminogen activator activity in endometriosis and pelvic adhesive disease.

Plasminogen activator activity in PF was assayed by the fibrinolysis method described by Strickland and Beers. In 45 patients studied, there were no discernible differences according to whether patients had endometriosis and/or pelvic adhesive disease. No differences were detected according to when in the menstrual cycle the sample of PF was obtained. These data are in concordance with a previous report and taken together suggest that there is no difference in fibrinolytic mechanisms in PF in patients with or without endometriosis and/or pelvic adhesive disease, when compared with control subjects. If such differences exist, they may be present in the tissues, per se, but are not discernible in PF.

Ascitic Fluid↗
PubMed1984

Fasciola hepatica: the effects of neuropharmacological agents upon in vitro motility.

The effects of a wide range of neuropharmacological agents on the motility in vitro of Fasciola hepatica have been determined using an isometric transducer system. The neuromuscular blocking agents tubocurarine and decamethonium cause a long-term stimulation of the basal activity of the fluke. Acetylcholine causes an inhibition of activity. This effect is mimicked by the cholinergic agonists carbachol and nicotine, antagonised by the cholinergic blocking agents atropine and mecamylamine, and potentiated by eserine, a cholinesterase inhibitor. With nicotine and atropine the effects are accompanied by an increase in muscle tone at a concentration of 1 X 10(-2) M. Noradrenaline and adrenaline also cause some inhibition of activity, an effect antagonised by guanethidine, which blocks the release of noradrenaline. In contrast, dopamine stimulates fluke motility, whilst its antagonist dihydroergotamine causes an inhibition of activity. The monoamine oxidase inhibitors iproniazid and p-chloromercuribenzoic acid induce a stimulation of activity; with the latter there is an increase in muscle tone at a concentration of 1 X 10(-3) M. The amine depleting agents chloroamphetamine and reserpine, and the monoamine uptake inhibitors desipramine and nortriptyline produce an inhibition of fluke activity, as does the serotonin uptake inhibitor fluoxetine. High concentrations of chloroamphetamine (1 X 10(-2) M) and the uptake inhibitors (1 X 10(-3) M and above) also induce an increase in muscle tone. Serotonin causes a marked stimulation of motility. The pharmacological evidence is consistent with a neurotransmitter role of acetylcholine (inhibitory), dopamine (excitatory), and noradrenaline (inhibitory). The status of serotonin is discussed.

Animals↗
PubMed1984

Fasciola hepatica: motility response to fasciolicides in vitro.

The effects of a wide range of fasciolicides on the in vitro motility of Fasciola hepatica have been determined by means of an isometric transducer system. Carbon tetrachloride and diamphenethide do not affect movement at concentrations up to 500 and 100 micrograms/ml, respectively; at 1000 micrograms/ml, however, carbon tetrachloride induces a rapid tonic paralysis. Brotianide and the deacetylated metabolite of diamphenethide cause a rapid flaccid paralysis of the fluke at concentrations of 1.0 micrograms/ml and above. In contrast, the effect of MK-401 is a long-term one, a flaccid paralysis occurring after 20 hr only at 200 micrograms/ml. Praziquantel also produces a flaccid paralysis of the fluke, but this follows an initial increase, then decrease in muscle tone. The effect is rapid at 500 micrograms/ml, but long-term at 100 and 200 micrograms/ml; at these lower concentrations there is also a stimulation of activity. Oxyclozanide , rafoxanide, niclofolan , bithionol, and hexacholorophene induce a rapid spastic paralysis of the fluke at concentrations of 1.0 micrograms/ml and above. Both phasic and tonic components are evident in the response at concentrations of 1.0 micrograms/ml and below; the phasic component disappears at higher concentrations. Nitroxynil produces a similar effect, evident at higher concentrations. Among the benzimidazoles, mebendazole, oxfendazole, and albendazole sulphoxide cause a suppression of motility, whilst thiabendazole and albendazole produce a stimulation of movement. The effects are not rapid, however, for only mebendazole at 500 micrograms/ml causes total inactivity of the fluke within a 12-hr period. Possible explanations for these effects on fluke motility are discussed.

Albendazole↗
PubMed1984

Regulation of transferrin secretion by human Sertoli cells cultured in the presence or absence of human peritubular cells.

Transferrin represents 1-4% of the total proteins secreted by human Sertoli cells, and the amount secreted by the cells was maximal after a 4- to 5-day period in culture, the time chosen for each medium change. During this first 4- to 5-day period, the addition of FSH, insulin, (Bu)2cAMP, and isobutylmethylxanthine had no effect on transferrin secretion; however, from days 4-5 to 8-10, each of the above compounds significantly stimulated transferrin secretion compared to control values. Testosterone (in the absence or presence of insulin) had no effect. Transferrin secretion increased for the first 5 days in culture, with a similar magnitude in the presence or absence of the above stimulators, and thereafter declined, more so in untreated cultures. These results suggest that these agents do not stimulate, but, rather, limit the decline in transferrin secretion. When human peritubular cells were cocultured with Sertoli cells, transferrin secretion was significantly elevated compared to that by Sertoli cells alone. Interestingly, in the cocultures (Bu)2cAMP stimulated transferrin secretion when added for the first 4- to 5-day culture period. Human fibroblasts or spent medium from the peritubular cell cultures did not mimic the effect found when peritubular and Sertoli cells were cocultured. These results provide evidence that peritubular cells play a critical role in regulating human Sertoli cell function.

1-Methyl-3-isobutylxanthine↗
PubMed1983

Identification of histidine and methionine residues in the active site of the human uterine progesterone receptor with the affinity labels 11 alpha- and 16 alpha-(bromoacetoxy)progesterone.

The affinity labels 11 alpha- and 16 alpha-(bromo[2'-3H]acetoxy)progesterone (BAP) react covalently with amino acids present in the progesterone binding site of the human uterine progesterone receptor. Hydrolysis of the affinity labeled receptor followed by separation and analysis of the amino acid products demonstrated the sites of affinity labeling. The 11 alpha-BAP alkylates the 1-position of a histidine residue. The 16 alpha-BAP alkylates the 3-position of histidine, and a methionine residue. Affinity labeling did not occur in the presence of excess progesterone, and under the optimum conditions for affinity labeling of the receptor, heat-denatured receptor, bovine serum albumin, and 20 beta-hydroxysteroid dehydrogenase were not affinity labeled. This is the first report of the identification of specific amino acid residues in the binding site of a steroid hormone receptor.

Affinity Labels↗
PubMed1983

Fasciola hepatica: a technique for monitoring in vitro motility.

An apparatus utilizing a force and displacement transducer is described for the direct and long-term recording of the motility in vitro of Fasciola hepatica. Normal movement is typically rhythmical, with bursts of more powerful contractions alternating with periods of lesser activity. Such rhythms and the overall level of activity are maintained for more than 30 hr. The fluke remains active for much longer periods of time: recordings of fluke movements have been made for up to 4 days. Potential damage to the fluke caused by the attachment system within the recording apparatus has been determined by the Evans' Blue Technique and scanning electron microscopy. It is restricted to the attachment sites, and does not spread to other parts of the body over the 30-hr normal activity period. Transmission electron microscope studies have shown that the tegument retains its structural and functional integrity over this period of time. There are advantages of the recording apparatus over previous kymographic methods for studying fluke motility.

Animals↗
PubMed1983

Transferrin binds specifically to pachytene spermatocytes.

We have examined the secretion and binding of transferrin to rat testicular cells. The only testicular cells found to secrete transferrin were the Sertoli cells (control 549 +/- 6; FSH 1020 +/- 17 ng/day X 10(6) cells, mean +/- SEM). The Sertoli cells also contained specific binding sites for transferrin with a Kd of 2.0 X 10(-9)M. Of the other testicular cells examined only fractions rich in pachytene spermatocytes possessed specific transferrin-binding sites. Late pachytene spermatocytes (97% pure) bound [125I]iodotransferrin with a similar affinity as Sertoli cells (Kd 1.7 X 10(-9)M). Fractions of early and mid pachytene spermatocytes contained transferrin-binding sites with a higher affinity (Kd 0.3 X 10(-9)M). This is the first report of a protein that has specific binding sites on germ cells.

Animals↗
PubMed1983

Effect of cannabinoids on human Sertoli cell function in vitro.

Exposure to marijuana adversely affects spermatogenesis in humans and rodents. Since the Sertoli cell interfaces between changes in the serum hormonal milieu and the adluminal compartment and acts in various ways to support the germinal epithelium, this adverse marijuana mediated effect might be transmitted locally in the testes of humans by interference with Sertoli cell function. This report describes the effect of three active marijuana components: delta-9-tetrahydrocannabinol (THC), cannabidiol (CD) and cannabinol (CN) on various human Sertoli cell markers: transferrin, protein secretion and gamma glutamyl transpeptidase activity utilizing cultured human Sertoli cells. THC, CD, and CN tested in concentrations up to 200 ng/ml did not change transferrin secretion by these human Sertoli cells. Transferrin represents 1-4% of the total newly synthesized proteins of human Sertoli cells in culture. Even when the Sertoli cells were incubated for 30 days with THC there was no effect on transferrin secretion. The presence or absence of follicle-stimulating hormone, testosterone (T) or Fe3+ in the culture media did not modify the effect of THC. THC, CD, and CN also did not alter total protein secretion by Sertoli cells nor affect the level of gamma glutamyl transpeptidase activity.

Acyltransferases↗
PubMed1982

Hymenolepis diminuta: the mechanism of egg hatching.

The fine structure and histochemistry of the envelopes surrounding the mature oncosphere of Hymenolepis diminuta have been investigated by transmission electron microscopy and light microscope observations of JB-4 embedded material. The fate of these envelopes during the hatching sequence in vitro has been followed by phase-contrast and scanning electron microscopy. Hatching is considered to comprise 4 stages. Stage 1 involves the mechanical breakage and removal of the shell and the outer cytoplasmic layer of the inner envelope; Stage 2 the activation of the oncosphere and the swelling of the gelatinous layer of the inner envelope; and Stage 3 the digestion and rupture of the embryophore. This is accomplished both by secretions from the penetration gland and by the action of external digestive enzymes, together with hook activity. Trypsin is more effective than amylase in digesting the embryophore. Stage 4 involves the enzymatic weakening of the gelatinous layer which helps the oncosphere to tear itself free with its hooks. Amylase is more effective than trypsin in attacking the gelatinous layer. On emergence from the gelatinous layer, the oncosphere is still enveloped by the 'oncospheral membrane', although this covering is soon lost. Once activated, the oncosphere is capable of completing the hatching sequence by itself, without the addition of enzymes. This process is a lengthy one, however, taking up to 2 h, and the expenditure of its glandular and energy reserves makes successful gut penetration by the oncosphere unlikely.

Amylases↗
PubMed1982

Transferrin and gonadal dysfunction in man.

Transferrin concentrations were quantitated in the seminal fluid of normal, oligozoospermic, and azoospermic patients and related to other known parameters of testicular function. Transferrin concentration in the semen of patients 2 months after vasectomy (13.2 +/- 1.8 micrograms/ml) was significantly less than that obtained from pregnancy-proven donors (65.6 +/- 10.1 micrograms/ml). This indicates that approximately 80% of the seminal fluid transferrin is derived from the testes. The concentration of transferrin in semen from patients with azoospermia (14.4 +/- 1.8 micrograms/ml), severe oligozoospermia (17.5 +/- 1.7 micrograms/ml), and moderate oligozoospermia (21.8 +/- 4.3 micrograms/ml) was significantly lower than normospermic groups. Serum follicle-stimulating hormone (FSH) was measured in a group of infertile patients; those having an elevated FSH had a significantly lower concentration of semen transferrin, 14.1 +/- 1.6 micrograms/ml, compared with patients who had FSH levels within the normal range (33.7 +/- 5.3 micrograms/ml). It is possible that the underlying cause in decreased spermatogenesis associated with both an elevated FSH and a decreased transferrin concentration is impaired Sertoli cell function.

Follicle Stimulating Hormone↗
PubMed1981

Effects of interferon on the cAMP-adenylate cyclase system of human, mouse, and bovine thyroid tissue.

This report studied the action of interferon on the thyroidal adenylate cyclase-cAMP system. It was found that human interferon did not increase cAMP levels in human or bovine thyroid slices during a 60-min incubation. Mouse interferon also had no effect on cAMP levels in mouse thyroidal lobes over the 60-min incubation, nor did it increase adenylate cyclase activity in mouse homogenates.

Adenylyl Cyclases↗
PubMed1981

Affinity labelling of the human uterine progesterone receptor with 21-, 16 alpha- and 11 alpha-bromoacetoxyprogesterones.

This report describes the use of 21-, 16 alpha- and 11 alpha -[2'-3H]bromoacetoxyprogesterone as affinity labels to characterize the human uterine progesterone receptor (HPR). These three derivatives can bind to and displace progesterone bound to the HPR. This affinity labelling was inhibited by an excess of radioinert progesterone and could not be demonstrated if bovine serum albumin was used in place of the HPR. Bromoacetic acid alone did not affinity label the HPR. Polyacrylamide gel electrophoresis under denaturing conditions showed that all three derivatives bound to a 45,000 molecular weight protein.

Affinity Labels↗
PubMed1980

Effect of increased circulating thyroid-stimulating hormone on in vitro thyroid-stimulating hormone stimulation of thyroid and adipose tissues.

Hormones have been shown to regulate the number and/or binding properties of their own receptors. The present studies examined the effect of chronic increased endogenous TSH levels, induced by tapazole or thyroidectomy, on in vitro TSH responsiveness and binding in thyroid and adipose tissues. The results showed that TSH and prostaglandin E1 significantly increased cAMP levels in the thyroids of weight- and age-matched controls, whereas thyroids from tapazole-treated rats responded only to prostaglandin E1. Iodide organification was also measured, and the thyroids from tapazole-treated rats showed a significantly reduced effect of TSH compared to weight- and age-matched controls, although stimulation by dibutyryl cAMP was equivalent in all three groups. TSH or epinephrine stimulation of cAMP and glucose oxidation was equivalent in adipose tissue from control and hypothyroid rats. There was a significant 50% reduction in the number TSH-binding sites in thyroids from tapazole-treated rats: the affinity remained unchanged. [125I]TSH binding to adipose tissue plasma membranes was similar in control and hypothyroid groups. These studies demonstrate that elevated levels of TSH appear to regulate the number of TSH receptors in thyroid, but not adipose, tissue.

Adipose Tissue↗