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Biomedical subjects

J R Jones

Publications and source records attributed to J R Jones.

At least 73 records · Page 4Linked to original sources
PubMed1986

The locked knee.

Fifty patients presenting themselves with a locked knee were investigated prospectively by examination under anaesthesia and arthroscopy. Definite abnormality was found in 92 per cent. Torn menisci were present in 68 per cent and isolated ruptures of the cruciate ligament in 10 per cent. Loose bodies were found in 3 patients, degenerative changes alone in 2 patients and a pathological medial synovial shelf in 1 patient. No abnormality was demonstrated in 8 per cent. Sixteen per cent of the knees remained locked following the induction of anaesthesia. This study demonstrates that a true mechanical block is not necessarily present and that the position of an unstable meniscal fragment is not consistently related to the fixed position of the knee under anaesthetic. There were no clinical features that allowed the normal knees to be distinguished preoperatively from those with internal derangement. It is proposed that these patients should be managed by prompt examination under anaesthesia, arthroscopy and definitive surgery.

Adolescent↗
PubMed1985

A comparative examination of the in vitro metabolism of five cyclopenta[a]phenanthrenes of varying carcinogenic potential.

Metabolites of 15,16-dihydrocyclopenta[a]phenanthren-17-one and its 1- and 12-methyl homologues (all non-carcinogens) along with those from the 11-methyl and 11,12-dimethyl-17-ketones (carcinogens), produced in vitro by hepatic microsomes from methylcholanthrene induced rats, were separated by reverse phase h.p.l.c. Identifications of individual metabolites were based upon elution times, u.v. spectra, and in some cases by mass spectrometry, circular dichroism, and identity with synthetic derivatives. All five compounds were biologically oxidised at their terminal A and D rings to yield 1,2-dihydrodiols and 15- and 16- ols; with the exception of the 1-methyl compound, all also gave similar amounts of 3,4-dihydrodiols. The 1-methyl compound by contrast failed to produce this metabolite, furnishing instead the 4-phenol and five other, probably related phenolic derivatives. Previous work has established that for the 11-methyl-17-ketone, the 3,4-dihydrodiol is the proximate carcinogen. Thus, whereas lack of biological activity with the 1-methyl compound can be ascribed to its failure to produce a 3,4-dihydrodiol, in the case of the unsubstituted parent ketone and its 12-methyl derivative other determining factors must come into play.

Animals↗
PubMed1985

Comparison of the binding of some carcinogenic and non-carcinogenic cyclopenta[a]phenanthrenes to DNA in vitro and in vivo.

After microsomal activation in vitro, both the strong carcinogen 15,16-dihydro-11-methylcyclopenta[a]phenanthren-17-one and its inactive 12-methyl isomer bind covalently to added DNA, in the ratio approximately 6:1 (1595 and 254 mu mol/mol of DNA phosphorus, respectively). Over a thousand times less binding was observed when DNA was isolated from the skin of groups of mice that had received a topical dose of 1000 nmol of these two compounds, and of the unsubstituted ketone (non-carcinogen) and its 11,12-dimethyl derivative (carcinogen), 48 h previously; the binding ratios were 458, 155, 19 and 974 nmol/mol DNA phosphorus, respectively. Covalent binding of the 11-methyl compound to mouse skin DNA, measured 48 h after topical application, was linear with dose over the range 50 - 1000 nmol. It has previously been demonstrated for groups of mice initiated with 200 or 400 nmol of this carcinogen and promoted by repeated application of croton oil that skin tumour incidences were 50 and 70%, respectively. For a topical dose of 1000 nmol of the inactive 12-methyl isomer DNA binding in skin falls in this range, equivalent to DNA binding given by approximately 340 nmol of the carcinogen. Thus although the inactive unsubstituted parent compound essentially fails to bind to skin DNA after topical application, there does not seem to be a consistent relationship between extent of DNA binding in vivo and carcinogenicity among these cyclopenta[a]phenanthrenes. However, loss of the 12-methyl adducts from skin followed a logarithmic course over the first 10 days following application, with a half life of 3.5 days. In contrast, it was previously shown that removal of the 11-methyl adducts could not be measured above the normal rate of DNA turnover for this mouse tissue (half life, 6-7 days). It is suggested that active DNA repair of the 12-methyl lesions may contribute to the lack of activity of this isomer.

Animals↗
PubMed1984

The physical digestion of perennial ryegrass (Lolium perenne) and white clover (Trifolium repens) in the foregut of sheep.

Sheep were fed once daily with 300 or 600 g dried perennial ryegrass (Lolium perenne) or white clover (Trifolium repens). Total rumen contents were sampled once daily at various intervals up to 24 h after feeding for 6 d. Total weight of fresh rumen contents and dry matter (DM), organic matter and particulate matter concentrations were measured and the particle size distribution of rumen contents was analysed using a wet sieving technique. There was a similar exponential loss of DM from the rumen with time after feeding for both perennial ryegrass and white clover. The rate of DM disappearance during the first 3 h after feeding was ten times greater for the higher intake and seven times greater for the lower intake than during the subsequent 21 h. The percentage of particulate material disappearing during the first 3 h was greater for white clover (57%) than for perennial ryegrass (49%). Particle size distribution analysis of rumen contents showed that the most rapid rate of particle size reduction occurred during the first 3 h after feeding. Despite a rapid rate of breakdown there was no increase in the total weight of small particles in the rumen. The rate of reduction in particle size during this period was greater for white clover than perennial ryegrass. Microscopic examination of rumen particles showed a difference in particle geometry between white clover and perennial ryegrass which appeared to be related to anatomical features of the plant.

Animal Feed↗
PubMed1983

Hyperprolactinemia and headaches.

We investigated the frequency of headaches in women with menstrual abnormalities and hyperprolactinemia. Twenty-seven of 46 (58%) women with hyperprolactinemia indicated that headache episodes occur once or more per week; patients with sellar abnormalities (macroadenoma) or previous cranial or pituitary operation were excluded from this group of hyperprolactinemic patients. The headache episodes occurred significantly more frequently than in the control group (N = 56), where 27% indicated one or more headaches per week (p less than 0.01). In the vast majority of the women with hyperprolactinemia, headaches had preceded the finding of elevated prolactin levels for years and had not developed after the patients had become concerned about the pituitary gland. The clinical impression was that the headaches of these patients typically lack features of prodromal signs and unilaterality and resemble, in general, tension headaches; they may last for hours and often require medication. We could not demonstrate a relationship between prolactin levels and frequency or severity of these headache episodes. The etiology of these headaches is unclear. The therapeutic effect of bromocriptine deserves further investigation. In conclusion, we present data to suggest that headaches are commonly an associated finding in hyperprolactinemic women who have no evidence of significant pituitary enlargement.

Adenoma↗
PubMed1983

Sequential clomiphene citrate-menotropin therapy for induction or enhancement of ovulation.

Either to induce ovulation in anovulatory infertility patients or to enhance ovulation in patients with mild endometriosis or luteal phase inadequacy, we utilized a sequential regimen of low-dose clomiphene citrate (CC) followed by human menopausal gonadotropin (hMG) injections on alternate days; duration and dosage of menotropin therapy was individualized by using serum estradiol levels for monitoring until the time of administration of human chorionic gonadotropins. Previous therapeutic efforts without menotropins had been unsuccessful in all patients. One third of 70 treated patients conceived during 156 treatment cycles. The pregnancy rate was 44% in anovulatory patients (n = 34), and 26% in patients with ovulation dysfunction (n = 23). Pregnancy rates declined with patient's age. Four of the 23 patients that conceived had a spontaneous abortion (17%). The multiple gestation rate was 10.5%. A relative inhibition of cervical mucus development was noted and shown to be caused by CC. Hyperstimulation occurred in three patients. The discussed CC-hMG regimen approaches the effectiveness of standard hMG therapy; but compared with standard hMG therapy, it has significant economic advantages and seems to have a markedly lower rate of multiple gestation. However, like standard hMG therapy, CC-hMG therapy requires careful monitoring specifically, because hyperstimulation may occur.

Adult↗
PubMed1982

Antenatal diagnosis of sickle cell disease: amniotic fluid cell DNA analysis.

Using recombinant DNA methods and amniocentesis, the antenatal diagnosis of sickle cell disorders can be accomplished. This article presents the authors' experiences with 21 pregnancies at risk using HpaI and Hind III restriction enzyme digestions of adult leukocytic and fetal amniotic fluid cell DNA. The authors were able to establish direct beta A- and beta S-globin gene linkages to the restricted fragments in 9 families. In 8 families no direct linkages could be determined and estimates of exclusion of fetal beta S homozygosity were used. These estimates were made on the basis of the frequencies of association of the HpaI fragments with the beta S and beta A genes in the Afro-American population. In 4 families, no estimates or linkages could be established, and the patients were counseled in reference to fetoscopy. The data also indicated the frequencies of association of the HpaI fragments with the beta A and beta S gene in the New Jersey-New York population. These studies did not seem to indicate any exclusive preferential segregation of the HpaI and Hind III polymorphisms.

Amniotic Fluid↗