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Biomedical subjects

D R Jones

Publications and source records attributed to D R Jones.

At least 253 records · Page 14Linked to original sources
PubMed1988

Effect of denervation of carotid labyrinths on breathing in unrestrained Xenopus laevis.

The effect of denervation of the carotid labyrinths on breathing responses to simultaneously applied aerial and aquatic normoxia, hypoxia, or hypercapnia has been studied in unrestrained Xenopus laevis. Denervation significantly reduced VI of normoxic toads compared with VI in intact and sham-operated toads, due to a significant reduction in the volume of each buccal pumping movement (VB) in denervates. Breathing increased significantly in response to environmental hypoxia or hypercapnia in intact and sham-operated toads as well as in denervates. Breathing frequency (fRESP) was the major determinant of the increase in VI for VB was unchanged and even fell slightly in denervates in hypercapnia. Dive time (DT) was significantly reduced in both hypoxia and hypercapnia, from that in normoxia. DT fell significantly more in hypoxia than in hypercapnia in both denervates and intact and sham-operated toads. It is concluded that the carotid labyrinth does not play a major role in regulating breathing in hypoxia or hypercapnia in unrestrained Xenopus.

Animals↗
PubMed1988

X-ray microscopy of the prostate gland.

A technique is described for investigating the internal structure of the prostate gland (including calcification) by projection X-ray microscopy (microradiography). The results show that the technique can be used in conjunction with the corresponding histological preparations to complement the examination of the prostate gland by demonstrating tissue density and the structure and location of microcalcification less than 5 microns in diameter.

Humans↗
PubMed1988

Intracerebral metastases from ocular melanoma.

A blind painful eye may harbour an unsuspected malignant melanoma. We report a case of ocular melanoma that presented with confusion owing to direct extension via the optic nerve into the anterior cranial fossa.

Aged↗
PubMed1988

Heparin and acute inflammation in the rat.

The subcutaneous injection of heparin into the dorsal cervical region of rats 30 min before the intrapedal administration of carrageenin significantly impaired the local inflammatory reaction from 2 h through to 6 h. This observation implies that the release of endogenous heparins from tissue mast cells may play a role in modulating the extent of the response to inflammatory insults.

Acute Disease↗
PubMed1988

Brain uptake of benzodiazepines: effects of lipophilicity and plasma protein binding.

The rapid intracarotid injection technique was used to determine the unidirectional brain uptake of a number of benzodiazepines in the rat. The drugs varied considerably in their lipophilicity and, within the series oxazepam, lorazepam, chlordiazepoxide, desmethyldiazepam and diazepam, brain extraction of unbound moiety was enhanced as the octanol-water (pH = 7.4) partition coefficient increased. However, with flunitrazepam and midazolam, two fluorine-containing benzodiazepines, extraction was more and less extensive, respectively, than predicted from their lipophilicities. Importantly, the uptake findings were consistent with the characteristic onsets of central effects of the drugs established clinically in humans. The effects of reversible protein binding on uptake also were investigated by the addition of albumin (0-8 g.dl-1) to the injectate. This affected markedly the unbound fraction, determined in vitro by equilibrium dialysis, and also the brain uptake of all drugs. As the unbound fraction was reduced, the unidirectional brain extraction ratio decreased in a curvilinear fashion toward zero. However, attempts to describe the data were unsuccessful using a conventional model based on transcapillary uptake of only unbound drug whose binding kinetics with albumin were assumed to be the same as those indicated by equilibrium dialysis. The observed brain extraction was greater than predicted, and the discrepancy became more apparent as binding and albumin concentration increased. The data for all of the benzodiazepines could be fitted, however, if the equilibrium association constant was assumed to be smaller in vivo than in vitro, so that the effective unbound fraction in the brain capillaries was substantially higher (5- to 25-fold, dependent on the particular drug) than that estimated in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Unemployment and mortality: comparison of the 1971 and 1981 longitudinal study census samples.

Mortality in the period 1981-3 among men in the Office of Population Censuses and Surveys longitudinal study who were seeking work in 1981 was examined to investigate whether the finding of a high mortality rate among a comparable group of men who were followed up from the 1971 Census was repeated despite appreciable changes in the size and structure of the labour force over the intervening years. The pattern of mortality shortly after both censuses suggests that sick unemployed men were not categorised as seeking work, and it is concluded that for both samples the mortality of those who were reported to be seeking work was raised for reasons other than initial poor health. Other findings from the two censuses are also broadly similar. If confirmed after longer follow up this will add considerably to the evidence of the adverse health consequences of unemployment.

Adolescent↗
PubMed1987

Prospectively randomized clinical trial to compare in situ and reversed saphenous vein grafts for femoropopliteal bypass.

Two hundred and fifteen femoropopliteal bypass procedures using autologous saphenous vein grafts were randomly allocated to either the reversed or in situ technique. Eleven veins (5 per cent) were rejected at operation on the basis of their small size, nine in the reversed group and two in the in situ group, and there were two (2 per cent) perioperative deaths in each group, leaving 102 reversed and 98 in situ grafts for further study. The cumulative patency at 3 years of the reversed grafts was 77 per cent and that of the in situ grafts was 68 per cent (n.s.). The patency of all grafts was affected adversely by small veins (P less than 0.005), long grafts (P less than 0.05), low volume of blood flow in the grafts (P less than 0.001) and poor run-off (P less than 0.05). These factors influenced the outcome of the in situ and reversed operations to a similar degree and there was no statistically significant difference between them within any subgroup. The mean compliance of the in situ grafts measured 3 months or more after operation with an ultrasonic echo-tracking system was 0.024 +/- 0.01 per cent/mmHg (+/- s.d.) compared with 0.017 +/- 0.01 per cent/mmHg for the reversed grafts (t = 2.43, P less than 0.02). The incidence of fibrous stricture formation as shown by intravenous digital subtraction angiography was 29 per cent in both the reversed and the in situ grafts. The results of the study to date indicate that reversed and in situ vein grafts are equally effective for femoropopliteal bypass.

Adult↗
PubMed1987

Heart disease mortality following widowhood: some results from the OPCS Longitudinal Study. Office of Population Censuses and Surveys.

Many studies have suggested that following the experience of 'stressful' life events the risks of myocardial infarction, accidents and perhaps other diseases are elevated. In the OPCS Longitudinal Study routinely collected data on deaths, and deaths of a spouse occurring in a 1% sample of the population of England and Wales in the period 1971-1981 are linked together, and with 1971 census records of sample members. The timing and patterns of death following the potentially very stressful event of conjugal bereavement may thus be analysed. Overall the mortality (from ischaemic heart disease) was less than 10% in excess of that in all members of the LS sample. As in many earlier studies, some increases in death rates shortly after widowhood are observed. Unusually, for deaths from all causes these increases are more marked in widows than in widowers with, for example, a two-fold increase in mortality from all causes in the first month after widowhood. However, no peak of post-bereavement mortality from ischaemic heart disease is clearly established in either sex. Although the study is large, with a well-chosen control group, only a limited characterisation of study members from data collected in the census is possible. In particular, no measures of personality, behaviour or diet are available. Investigation of potential effects of social or familial support, as measured by household structure and numbers of children, led to equivocal results. Several possible explanations for the increased mortality rates are examined. Hypotheses based on common marital environment, homogamy or simultaneous accidental death are seen to be of very limited value. The observed patterns, although consistent with an early effect of a stressful life event, do not suggest that stress following bereavement leads to an excess of ischaemic heart disease mortality.

Coronary Disease↗
PubMed1987

An enzyme-linked antiglobulin test for the detection of erythrocyte-bound antibodies in canine autoimmune haemolytic anaemia.

A method has been developed which allows identification and quantitation of red cell-bound immunoglobulins and complement in canine blood. The technique utilizes ELISA methodology and the assay identifies cases of autoimmune haemolytic anaemia which are negative by the Direct Coombs test. Further, the amount of antibody present on the red cells shows a close correlation to the haemoglobin level; suggesting that the degree of sensitization of the RBCs influences their rate of destruction. Favourable response to treatment correlates with a decrease in the levels of bound antibody and complement.

Anemia, Hemolytic, Autoimmune↗
PubMed1987

The ultrasound appearances of prostatic cancer with histological correlation.

An analysis of the ultrasound appearances of the prostate with its capsule and periprostatic structures was performed in 221 patients with a histologically confirmed diagnosis of prostatic cancer. The cancers were histologically graded into well, moderate and poorly differentiated adenocarcinoma and transitional cell carcinoma. The results of this study indicate that an ill-defined hypoechoic area is the commonest appearance of prostatic cancer; this was seen in 96% of our 221 patients. The cancers were staged by ultrasound into confined (T0, T1, T2) and unconfined (T3) cancers. A breach of the capsule was seen in 55% of cases. In this unconfined group all cancers were hypoechoic in comparison with 92% in the confined group. In the confined cancer group the areas of abnormal echogenicity were present in more than one prostatic quadrant in 76%. Mostly commonly two prostatic quadrants were affected. The abnormal echogenicity was noted in the posterior quadrants of the prostate more commonly (58%) than in the anterior quadrants. The prostate gland appeared round in 67%, semicircular in 25% and crescentic in 8%. The gland was symmetrical in 68%. The prostatic capsule appeared regular in 86% of patients with a confined cancer. In 70% of cases of extensive but confined cancer there was loss of demarcation between the central and peripheral zones of the gland. The unconfined cancer group all had a breach of the capsule and all glands were heterogeneous due to hypoechoic areas. The breach affected more than one quadrant in 81% and most commonly the capsular breach involved two prostatic quadrants. An anterior breach of the capsule was noted much more frequently than a posterior breach. Forty-four per cent of cases had three or four quadrants of the gland involved. In 3% of cases of proven prostatic cancer no definite ultrasound abnormality could be detected. Calcification was seen within the gland in association with the cancer in 63% with approximately equal frequency in confined and unconfined disease. The seminal vesicles showed definite evidence of infiltration in 10%. Both seminal vesicles were seen in 61% and thought to be normal. In 8% only one was seen. Failure to demonstrate either seminal vesicle occurred in 21%. There was no correlation between the ultrasound appearances of prostatic cancer and the histological grading of the tumour.

Adenocarcinoma↗
PubMed1987

Separan AP-273 and renal function: a novel natriuretic substance.

Recent studies have demonstrated that an anionic polyacrylamide (Separan, Union Carbide Corp.) decreased the formation of atherosclerotic lesions in the rabbit (Separan AP-30) and increased cardiac output (Separan AP-273) in the rat. Since the effect of these compounds on renal function was unknown, we investigated the dose-response relationship between Separan AP-273 and the renal excretion of electrolytes and water. In the anesthetized rat, intravenous injections of Separan at 0.01, 0.03, 0,10, and 0.30 mg/kg produced a dose-related increase in urine volume, sodium excretion, and osmolar clearance. Potassium excretion was increased less than twofold only at the maximal dose tested. At this high dose, the effect on sodium and water excretion was greater (five- and seven-fold, respectively). Creatinine clearance was not altered by these interventions. As well, the maximal dose studied was previously shown to have no effect on blood flow. These results indicate that Separan AP-273 is a potent diuretic and natriuretic substance. Taken together with similar studies using the poly(ethylene oxide) Polyox WSR N-60K, these results suggest that drag-reducing polymers may represent a novel group of compounds with diuretic and natriuretic effects.

Acrylic Resins↗
PubMed1987

Acid-base balance in ducks (Anas platyrhynchos) during involuntary submergence.

Measurements of all the major independent variables [arterial CO2 tension (PaCO2); strong-ion difference ([SID]), and total protein content, which approximate total weak acid concentration in plasma] are essential for understanding changes in acid-base balance in plasma. During involuntary submergence of 1, 2, or 4 min, PaCO2 in ducks increased and arterial pH (pHa) decreased. During 1-min dives there were no significant changes in any strong ions. In both 2- and 4-min dives, there was a significant increase in [lactate-], but because of an increase in equal magnitude of [Na+], [SID] did not change. During recovery from all dives the plasma remained acidotic for several minutes, although PaCO2 fell below predive levels in less than 1 min. [Lactate-] increased in the recovery period. There were no changes in total protein content during submergence or recovery. Breathing 100% O2 before 2-min dives caused a reduction in [lactate-] production and release during and after the dive, although due to a marked increased in PaCO2, pHa fell as low as in 4-min dives after breathing air. After 1 min of recovery, pHa returned to normal along with the restoration of the predive level of PaCO2. We conclude that the acidosis during involuntary submergence is due solely to an increase in PaCO2, whereas in recovery it is caused by decreased [SID].

Acid-Base Equilibrium↗
PubMed1987

Adrenal gland denervation and diving in ducks.

The extreme elevation in plasma levels of free norepinephrine (NE) and free epinephrine (EP), which occurs during forced diving of ducks (Anas platyrhynchos), was studied before and after denervation of the adrenal glands. In intact animals both NE and EP concentration increased by up to two orders of magnitude in a 4-min dive but by a significantly lesser amount if the duck breathed O2 before the dive. Denervating the adrenal glands reduced the amounts of both catecholamines (CA) released during dives, plasma EP decreased to 10%, and NE to 50% of values obtained before denervation. Breathing O2 before a dive virtually eliminated CA release in denervates, indicating that hypoxia was the important non-neural releasing agent. Hypoxia was also the most important neural releasing agent compared with hypercapnia, acidosis, or hypoglycemia. Adrenal denervation did not cause significant changes in heart rate, blood pressure, arterial blood gas tensions, pH, or plasma glucose during dives, although denervation caused increased variation in some of these variables. In ducks CA release in dives is largely due to decreasing arterial O2 partial pressure, and full expression of the response is dependent on intact innervation of the adrenal gland.

Adrenal Glands↗