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Biomedical subjects

B Hudson

Publications and source records attributed to B Hudson.

At least 145 records · Page 8Linked to original sources
PubMed1977

Malarial antibodies in tropical splenomegaly syndrome in Papua New Guinea.

Levels of species and class-specific malarial antibody were studied in 249 New Guineans with tropical splenomegaly syndrome (TSS) and in 87 control subjects living in the same area. Titres of IgG and IgM antibody to Plasmodium falciparum, P. vivax and P. malariae were estimated by indirect immunofluorescence. Both Ig and IgM antibody levels were higher in subjects with TSS than in controls; IgM titres were highest in those with the greatest splenic enlargement. Responses to all three species were comparable. It is concluded that there is no evidence from this study to incriminate any one species of malaria parasite in the production of tropical splenomegaly syndrome.

Adolescent↗
PubMed1977

Ethidium analogues with improved resolution in the dye-buoyant density procedure.

Analogues of ethidium chloride with large quaternary side chains have been synthesized and evaluated for improved resolution in the dye-buoyant density system for the separation of open and closed circular DNA. These compounds are similar to propidium which differs from ethidium by the replacement of an ethyl group by a methyldiethylaminopropyl group. The new analogues contain a triethylamino group attached to a methylene chain with 3, 5 or 7 carbons. With PM2 DNA the observed separation for propidium is 1.97 times that of ethidium and the new dyes show separations relative to ethidium of 2.27, 2.66 and 2.77. A correlation is established between the mass of the dye component and the observed separation which is retionalized on the basis of the four component thermodynamics describing this system.

Bacteriophages↗
PubMed1977

[Effect of an ovine pineal gland extract on prolactin release in vitro].

Defatted ovine pineal powder is submitted to acetic acid extraction followed by chromatographic separation. The extracted material and one of the two separated fractions inhibit the secretion of PRL by pituitary cells in monolayer culture. Both basal and TRH stimulated secretions are reduced.

Animals↗
PubMed1976

Resonance enhanced coherent anti-Stokes Raman scattering.

Resonance enhancement of coherent anti-Stokes Raman scattering due to the proximity of the laser frequencies to an electronic transition has been demonstrated for dilute solutions of diphenyloctatetrane in benzene. The Raman contribution to the third order susceptibility is shown to be complex near an electronic resonance and the resulting features of the coherent anti-Stokes Raman scattering spectra are discussed in detail. This work represents one step in the demonstration that the high signal to noise ratio, fluorescence rejection, and low average power levels of the coherent anti-Stokes Raman scattering experiment can be used to advantage in Raman studies of dilute solutions and materials of biological interest.

Benzene Derivatives↗
PubMed1976

Changes in the pituitary-testicular system with age.

In order to provide a comprehensive account of pituitary-testicular function in man, 466 subjects, ranging in age from 2 to 101 years, were studied to examine blood levels of the pituitary gonadotrophins (LH and FSH), the sex steroids testosterone and oestradiol, the binding capacity of the sex hormone binding globulin (SHBG), the free testosterone and oestradiol fractions, and the transfer constant for the peripheral conversion of testosterone to oestradiol. The results were compared with clinical indices of testicular size, sexual function and secondary sex hair distribution. Serum LH and FSH were low before puberty, increased in pubertal adolescents to levels somewhat above those of adults and subsequently increased progressively over the age of 40 years. Testosterone levels fell slowly after the age of 40, while there was a slight rise in plasma oestradiol with increasing age. FSH and testosterone showed small seasonal variations in young adult men, the lowest values being seen in winter. SHBG binding capacity was high in two prepubertal boys, fell in adult men, but increased in old age. Free testosterone and oestradiol levels fell in old age. The metabolic clearance rates (MCR) of testosterone and oestradiol also fell in old age, while the conversion of testosterone to oestradiol was increased. Many correlations were observed between various hormonal and clincial measurements. The evidence is consistent with a primary decrease in testicular function over the age of 40 years.

Adolescent↗
PubMed1976

Selective suppression of FSH by testicular extracts.

Studies were undertaken to determine the effects of intravenous infusions of bovine testicular extracts on plasma levels of FSH and LH in castrate male sheep. Decapsulated bovine testes were homogenized with phosphate buffer, the homogenates centrifuged at 30,000 X g for 30 min, and the supernatants extracted with diethyl ether. The aqueous extracts were filtered using Diaflo XM-100 membranes and the ultra-filtrates lyophilized. The extracts were infused over 24 hours, and plasma FSH and LH were measured prior to, during, and after the infusion. Control studies using infusions of saline and liver extracts demonstrated no decrease in FSH levels in 6 out of 7 controls, while LH levels tended to rise. Following infusions with the testicular extracts, the levels of FSH were selectively decreased to between 42% and 85% of baseline levels, and they subsequently remained suppressed for at least 24 hours. These results suggest that the testis is the site of production of a water-soluble, non-steroidal substance which exerts an inhibitory effect on the production and/or release of FSH.

Animals↗
PubMed1976

Regulation of gonadotrophin secretion in rams from birth to sexual maturity. I. Plasma LH, FSH and testosterone levels.

Plasma LH, FSH and testosterone concentrations were measured by radioimmunoassays in male crossbred Merino/Corriedale sheep from birth to 45 weeks of age. FSH levels were 11 and 22 ng/ml at birth, increased to peak levels (mean value of 47 ng/ml) at 5 weeks and fluctuated between 25 and 35 ng/ml for the next 40 weeks. Similarly, LH (less than 0-5 ng/ml) and testosterone (less than 38 ng/100 ml) levels were low at birth and were significantly elevated by 5 weeks of age. LH values varied betwen 0-9 and 3-0 ng/ml for the next 30 weeks and then a secondary rise occurred reaching levels of 2-4 ng/ml by the 41st week after birth. Concentrations of LH subsequently fell to levels observed in adult rams. Testosterone levels rose gradually between the 5th and the 25th week, and then increased rapidly to values of 270-517 ng/100 ml by the 41st week after birth, a time coincident with the peak LH levels. Histological examination of testicular biopsies demonstrated that Sertoli cell maturation occurred 17-21 weeks after birth and was followed by activation of spermatogenesis leading to the presence of spermatozoa in the seminiferous epithelium by 39-42 weeks of age.

Age Factors↗
PubMed1976

Regulation of gonadotrophin secretion in rams from birth to sexual maturity. II. Response of the pituitary-testicular axis to LH-RH infusion.

The response of the pituitary-testicular axis to LH-RH infusion was investigated in rams from birth to sexual maturity. During early postnatal life ram lambs were responsive to LH-RH stimulation and heightened pituitary sensitivity was observed in rams aged 2-3 months. It is suggested that a change in sensitivity of the pituitary-testicular axis occurs at this time and perhaps represents the time of initiation of the pubertal process.

Age Factors↗
PubMed1976

Studies on the relationship between FSH and germ cells: evidence for selective suppression of FSH by testicular extracts.

The evidence supporting the relationship between the seminiferous epithelium and circulating FSH levels has been reviewed and provides support for the concept that the testis produces a factor capable of specifically controlling FSH concentrations. Detailed quantitative histological studies of the seminiferous epithelium have demonstrated a highly significant inverse relationship between the number of spermatogonia per tubule cross-section and serum FSH levels in men with testicular disorders.

Animals↗
PubMed1976

A study of the endocrine manifestations of hepatic cirrhosis.

The clinical features and hormonal abnormalities were surveyed in 117 men with cirrhosis of the liver. Compared with healthy men of similar ages, the patients had significantly lower metabolic clearance rates, plasma production rates and total and free levels of testosterone, reduced testosterone responses to human chorionic gonadotrophin stimulation, higher oestradiol, luteinizing hormone and follicle stimulating hormone levels and higher binding capacities of sex steroid binding globulin. The peripheral conversion of testosterone to oestradiol was also found to be significantly increased. However, the metabolic clearance and plasma production rates of oestradiol were not significantly different from those of healthy men. Patients who were severely ill with liver failure and one with haemochromatosis had low levels of luteinizing hormone and follicle stimulating hormone and sub-normal responses to clomiphene and luteinizing hormone-releasing hormone. Higher plasma oestradiol levels were found in patients with gynaecomastia and spider naevi than in those without these signs. However, the clinical features of androgen deficiency--that is, testicular atrophy, impotence and loss of secondary sex hair--were only poorly related to the low testosterone levels, and production rates and longtitudinal studies indicated that the hormonal levels, endocrine features and severity of the liver disease could change independently. It is concluded that the clearance of oestradiol from plasma is not limited by liver disease in all patients, and that reduced degradation of oestrogens is not the initial event in the sequence leading to the hormonal abnormalities of cirrhosis. While gonadotrophin deficiency occurs with liver failure and in some patients with haemochromatosis, the more usual findings are of elevated gonadotrophin levels and a poor Leydig cell response to chorionic gonadotrophin. These suggest that the hypogonadism is primary in most patients with cirrhosis. The causes of the high oestradiol levels were not discovered. Increased peripheral conversion of precursors to oestradiol or increased testicular secretion of oestradiol are possibilities. The high binding capacities of sex steroid binding globulin were not significantly correlated with either the low testosterone or high oestradiol level and the cause of this abnormality remains uncertain. The low metabolic clearance rates of testosterone appeared to result from the increased plasma protein binding of testosterone. The discrepancies in the expected relationships between the hormone and clinical changes suggest that factors other than those studied are also involved in the genesis of the endocrine features of hepatic cirrhosis.

Adult↗