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Biomedical subjects

G Jones

Publications and source records attributed to G Jones.

At least 523 records · Page 29Linked to original sources
PubMed1979

Pathogenesis of rickets in chronic hepatobiliary disease in children.

To investigate whether hepatobiliary rickets is caused by defective intestinal absorption of vitamin D or by impaired hepatic hydroxylation of the vitamin, we studied three children who developed severe rickets, hypocalcemia, and hypophosphatemia, two despite having received 400 to 800 IU vitamin D per day by mouth, and one despite prolonged treatment with 10,000 IU daily. On oral vitamin D therapy, plasma vitamin D and 25-hydroxyvitamin D levels were low. When two children were treated with weekly intravenous doses of 3,000 IU vitamin D to approximate the recommended prophylactic allowance, their plasma calcium and phosphate values improved promptly, the radiographic lesions healed, and the plasma concentrations of vitamin D and 25-hydroxyvitamin D became normal. Our studies indicate that the primary cause of hepatobiliary rickets is intestinal malabsorption of vitamin D, not impairment of the hepatic metabolism of the vitamin.

Biliary Tract Diseases↗
PubMed1979

The effect of phenylephrine on excretion of fluid and electrolytes by the parotid and mandibular glands of the rat.

The effect has been investigated of the alpha-adrenergic agonist, phenylephrine, on excretion of water and electrolytes (Na, K, and HCO3) by the parotid and mandibular glands of the rat. In the mandibular glands the agonist was as effective as acetylcholine (or parasympathetic nerve stimulation) in stimulating secretion, and the electrolyte excretory patterns seen in the two modes of stimulation were similar. In the parotid gland, phenylephrine was only one-fifth as potent as acetylcholine (or parasympathetic nerve stimulation) in evoking a secretory response but, when due allowance for flow rate differences is made, the electrolyte excretion patterns were similar. In both glands the secretory response to phenylephrine was totally different, in magnitude and in electrolyte excretion pattern, to that evoked by the beta-adrenergic agonist, isoprenaline. It is concluded, as has already been established for secretion of exportable protein, that alpha-adrenergic agonists have very similar effects to muscarinic agonists both on endpiece and on duct cells and that these actions are completely different from those evoked by activation of beta-adrenergic receptors.

Animals↗
PubMed1979

Role of photosensitization and oxygen in chromosome stability and "spontaneous" malignant transformation in culture.

Visible light and oxygen enhanced both chromosome instability and malignant transformation of mouse cells in culture. Nine cell lines were initiated from 8 pools of 10- to 13-day C3H embryos. Each cell line was divided into sublines, which were either maintained shielded from light or were exposed for 3 or 24 hours to fluorescent light (approximately 150 foot-candles) two or three times weekly. Cultures of the sublines were also maintained with either a gaseous phase of 0-1% oxygen or atmospheric (18%) oxygen. Each line was monitored for cytologic manifestations of malignant neoplastic transformation, and 8 lines were monitored for chromosome alterations. Seven lines were assayed for tumorigenicity by intraocular implantation into syngeneic hosts. Repeated light exposure and/or high oxygen increased the frequency of minute chromosomes, which result from chromatid breaks, and also increased the rate of shift from diploid to heteroploid state. Four cell lines showed no cytologic changes indicative of neoplastic change during the test period. Two of these were assayed in vivo and failed to grow as tumors. In the remaining 6 lines, cytologically neoplastic colonies appeared earlier or more abundantly in the light-exposed cultures and/or those gassed with high oxygen. In 3 of these lines, tumors developed only from the light-exposed cultures; in the other 2, tumor latency periods were significantly shorter in the cultures exposed to light or gassed with atmospheric oxygen.

Animals↗
PubMed1979

The elution profile of vitamin D2 metabolites from sephadex LH20 columns.

A metabolite of vitamin D2 in the tissues of primates fed this vitamin co-migrates to a significant extent with 24,25-dihydroxyvitamin-D3 on columns of Sephadex LH20, with chloroform/n-hexane (60/40 by vol) as eluent. In individuals receiving vitamin D2 and in individuals with scant exposure to sunlight this metabolite, which we believe to be 25,26-dihydroxyvitamin-D2, may yield falsely higher concentrations of apparent 24,25-dihydroxyvitamin-D3 if separation on LH20 is used.

Animals↗
PubMed1978

Limitations of the cholecystogram.

There is a little doubt that the spontaneous passage of gallstones occurs sometimes without pain or jaundice. This is probably more frequent than is realised. While the cholecystogram is a reliable investigation and of great assistance to the clinician, occasionally a normal gallbladder will be demonstrated, when it has previously been the resting place of small gallstones. Four cases are described in which patients suffering clinically from cholelithiasis are shown to have a normal cholecystogram, but on repeat examinations gallstones are demonstrated in each case over intervals of one or two years. It is suggested that gallstones had been present in all these cases at the time of the initial symptoms, but could well have passed prior to the first examination.

Adult↗
PubMed1978

Linked Aryl Aryloxypropanolamines as a new class of lipid catabolis agents.

The synthesis of a series of stilbene, biaryl, tolane, diaryl ether, sulfide, sulfoxide, and sulfone oxypropanolamines as potential antiobesity agents is described. These compounds were evaluated in a mouse lipid catabolism screen, and the more active members of the series, 4, 57, and 58, were further investigated in rats and dogs. 1-(2,6-Ditert-butyl-4-trans-styrylphenoxy)-3-isopropylamino-2-propanol (4) possessed considerable lipid catabolic activity in mice and caused a significant reduction in the body weight of rats after 5 weeks and of dogs after 6 weeks. Only hematological irregularities in a chronic toxicity study precluded further development of this compound as an alternative antiobesity treatment.

Adipose Tissue↗
PubMed1978

Acute transverse myelopathy in childhood. A study of four cases.

Four cases and a literature survey show acute transverse myelopathy to be a dramatic but rare pediatric problem. Neurologic deficits can be significant but generally improve with the passage of time. The prognosis for complete recovery, however, is poor.

Acute Disease↗
PubMed1978

Assay of vitamins D2 and D3, and 25-hydroxyvitamins D2 and D3 in human plasma by high-performance liquid chromatography.

I describe a new assay that is capable of measuring vitamin D2, vitamin D3, 25-hydroxyvitamin D2, and 25-hydroxyvitamin D3 in 2 ml of plasma or serum. Plasma is extracted by the Bligh and Dyer technique [Can. J. Biochem. Physiol. 37, 911 (1959)], the lipid component is fractionated by two high-performance liquid-chromatographic systems based upon adsorption and reversed-phase chromatography, and each of the four vitamin D metabolites is measured by its absorbance at 254 nm. The method has a sensitivity limit of 0.5 mug/liter of plasma. The identity of metabolite peaks was confirmed by mass spectrometry, ultraviolet absorption spectrophotometry, and rechromatography, and there was good correlation (r=0.84) between plasma 25-hydroxyvitamin D as measured by the present method and by a protein binding assay developed in our laboratory. Mean concentrations of vitamin D and 25-hydroxyvitamin D in normal adults (n=25) in December were 2.2 +/- 1.1 (SD) and 16 +/- 3.9 (SD) mug/liter, respectively. 25-Hyroxyvitamin D2 made up 31% of the total 25-hydroxyvitamin D. Patients receiving pharmacological doses of vitamin D had values for vitamin D and 25-hydroxyvitamin D that were 10- to 100-fold normal. This method provides a rapid, reliable physico-chemical assay that appears to have advantages over existing protein binding assays and can be used to measure circulating vitamin D.

Adult↗
PubMed1978

Cytotoxic T lymphocyte sequential killing of immobilized allogeneic tumor target cells measured by time-lapse microcinematography.

Sequential killing of allogeneic target cells by immune cytotoxic T lymphocytes (CTL) was directly observed by time-lapse microcinematography. Target cells (EL4 lymphoma cells from C56BL/6 mice), coated with Fab fragments of goat antibody to EL4, were immobilized by binding to the floor of a polystyrene tissue culture flask that had been precoated with specifically purified anti-goat Fab. On adding immune BALB/c spleen CTL to such target cell monolayers it could be verified by direct observation that individual CTL could sequentially kill several target cells, that the CTL usually separated from the target cell before target cell death, that not all contacted target cells were killed, and that duration of contact was variable and not correlated with subsequent target cell death.

Animals↗
PubMed1977

Neonates at risk. Screening for deafness--practical or not?

Over a six-year period, 3,507 neonates in King George V Memorial Hospital, classified as being at risk for deafness, were screened for hearing. Although 144 failed to respond in the nurseries, 88 of them were cleared at a later test. The remainder, whether suspect, untraceable or still to return, would all be outside the neonatal period by now. No sensorineural impairment of hearing was detected in all neonates in the programme.

Australia↗