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Biomedical subjects

S R Jones

Publications and source records attributed to S R Jones.

At least 91 records · Page 5Linked to original sources
PubMed1993

Differentiation of acute from chronic renal impairment by detection of carbamylated haemoglobin.

Detection of carbamylated haemoglobin, measured as valine hydantoin per g haemoglobin (VH/g Hb), may be useful in differentiating between patients with acute or chronic renal failure. To assess this test, we measured carbamylated haemoglobin prospectively in 42 consecutive patients referred to the regional renal unit with a serum creatinine in excess of 500 mumol/L and a provisional diagnosis of acute renal failure (ARF). Patients were subsequently classed on clinical criteria as having ARF (20) or acute on chronic renal failure (AonCRF, 22). 24 patients with stable chronic renal failure (CRF), matched for degree of renal impairment, were also studied. Standard biochemical tests and haemoglobin were similar among the three groups. Patients with ARF of 10 or less days duration had a lower median (interquartile range [IQR]) carbamylated haemoglobin concentration than those with a longer duration of ARF (29 [27-35] vs 72 [60-83] micrograms VH/g Hb; p < 0.01). Carbamylated haemoglobin concentration was lower in the ARF group than in the AonCRF or CRF groups (42 [31-67], 116 [83-119], and 148 [122-210] micrograms VH/g Hb, respectively; p < 0.001). All patients with a degree of acute and potentially, reversible renal failure (ARF and AonCRF) had a carbamylated haemoglobin concentration below 190 micrograms VH/g Hb (sensitivity 100%, positive predictive value 62% for this cut-off). When the ratio of carbamylated haemoglobin to serum creatinine was calculated, to correct for degree of renal failure, a value of less than 0.2 had a 100% sensitivity and 80% positive predictive value for dividing patients with potentially reversible renal failure from those with CRF. Measurement of carbamylated haemoglobin was useful in identifying patients with acute and potentially reversible forms of renal failure. This test could be of clinical value in deciding which patients require urgent referral for further management and treatment in hospitals without specialist nephrological care.

Acute Kidney Injury↗
PubMed1993

Effects of inoculum route and dose on the immune response of common carp, Cyprinus carpio to the blood parasite, Trypanoplasma borreli.

Carp were inoculated intramuscularly (im) or intraperitoneally (ip) with different doses of live Trypanoplasma borreli. Prepatent period was shortened by using the im route and by increasing the dose. Haematocrit was reduced following im inoculation with 9.5 x 10(5) parasites. Most fish recovered between 8 and 13 weeks post-inoculation (wpi). Neither parasitaemia nor anaemia was detected in any recovered fish following homologous challenge. An enzyme-linked immunosorbent assay was developed to quantitate antibody response elicited by the parasite. Antibody levels rose rapidly during the first 4 wpi. The response elicited by increased dose was significantly higher only at 4 wpi. Route of exposure did not affect antibody response. Peak responses coincided with decline and eventual absence of parasitaemia.

Analysis of Variance↗
PubMed1993

Thyroxine replacement therapy and circulating lipid concentrations.

OBJECTIVE: Hypothyroidism is a common disorder and while the association of overt hypothyroidism with hypercholesterolaemia is clear, the effect upon lipids of the minor abnormalities of thyroid function often found in those receiving T4 replacement therapy is unclear. The aim of the present studies was to define in those with hypothyroidism the effect upon circulating lipids of subtle changes in thyroid status, indicated by serum TSH values below or above the normal range. DESIGN: (i) Prospective study of short-term T4 treatment of those with subclinical hypothyroidism. (ii) Cross-sectional study of long-term T4 treatment, comparing non-T4 treated controls and T4 treated patients with serum TSH values either below or within the normal range. PATIENTS: Short-term T4 therapy was examined in 11 post-menopausal females with subclinical hypothyroidism (high TSH, normal free T4) studied before therapy and 6 weeks after T4 at incremental doses (50, 100, 150 micrograms/day). Long-term T4 treatment for hypothyroidism was investigated in 105 females on therapy for at least 1 year compared with 105 controls matched for age and menopausal status. MEASUREMENTS: Fasting levels of total cholesterol, low density lipoprotein (LDL) cholesterol, high density lipoprotein (HDL) cholesterol and HDL subfractions were determined in patients and controls. RESULTS: (i) T4 treatment of subjects with subclinical hypothyroidism resulted in reductions in total and LDL cholesterol with increasing T4 dose (P < 0.001). Comparison of lipid results pretreatment with those when TSH was restored to normal revealed no significant difference in lipids; in contrast, comparison of lipids in those with normal TSH compared with the same subjects when TSH was suppressed revealed reductions in total and LDL cholesterol. (ii) Long-term T4 treatment was associated with a reduction in total and LDL cholesterol measurements in those over 55 years receiving suppressive doses of T4 but no significant difference in lipids in those with normal serum TSH compared with non-T4 treated controls. CONCLUSION: Effects of T4 upon lipid measurements suggest that patients with subclinical hypothyroidism should receive replacement therapy. Doses of T4 which suppress TSH to below normal may have a more significant influence upon lipids than doses of T4 which restore TSH to the normal range.

Aged↗
PubMed1993

Evoked extracellular dopamine in vivo in the medial prefrontal cortex.

The measurement of evoked extracellular dopamine in the medial prefrontal cortex by using fast-scan cyclic voltammetry with carbon-fiber microelectrodes was established and release characteristics of mesoprefrontal dopamine neurons were examined in vivo in anesthetized rats. Despite the sparse dopaminergic innervation and the presence of more dense noradrenergic and serotonergic innervations overall in the medial prefrontal cortex, the measurement of extracellular dopamine was achieved by selective recording in dopamine-rich terminal fields and selective activation of ascending dopamine neurons. This was confirmed by electrochemical, pharmacological, and anatomical evidence. An increased release capacity for mesoprefrontal dopamine neurons was also demonstrated by the slower decay of the evoked dopamine response after inhibition of catecholamine synthesis and the maintenance of the evoked dopamine response at higher levels in the medial prefrontal cortex compared with the striatum during supraphysiological stimulation.

Animals↗
PubMed1993

Thyroxine prescription in the community: serum thyroid stimulating hormone level assays as an indicator of undertreatment or overtreatment.

Examination of thyroxine usage in a study in the United States of America revealed that many patients were prescribed thyroxine for non-thyroid indications, such as obesity and fatigue. Many of those receiving thyroxine had high or low serum thyroid stimulating hormone levels, indicating prescription of incorrect doses or lack of patient compliance with therapy. Long term thyroxine therapy may have effects upon the risk of osteoporosis. The aims of this study were to investigate indications for thyroxine prescription in the United Kingdom and to examine the frequency of abnormal serum thyroid stimulating hormone concentrations in those prescribed thyroxine for hypothyroidism. This was in order to determine the relevance of measurement of thyroid stimulating hormone level in monitoring thyroxine therapy. Subjects receiving thyroxine were identified from the computerized prescribing records of four general practices in the West Midlands. Of 18,944 patients registered, 146 (0.8%) were being prescribed thyroxine; 134 of these had primary hypothyroidism and the remainder had other thyroid or pituitary diseases prior to treatment. Of the 97 patients with primary hypothyroidism who agreed to have their thyroid stimulating hormone level measured, abnormal serum levels were found in 48%, high levels in 27% and low levels in 21%. There was a significant relationship between prescribed thyroxine dose and median serum thyroid stimulating hormone level: high hormone levels were found in 47% of those prescribed less than 100 micrograms thyroxine per day, while low levels were found in 24% of those prescribed 100 micrograms or more. Thus, thyroxine prescription was common in the four practices sampled, although indications for its use were appropriate.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Cerebrovascular accident associated with dipyridamole thallium-201 myocardial imaging: case report.

A patient with known aortoiliac occlusive disease and hypertension suffered a cerebrovascular accident 6.5 min after the administration of intravenous dipyridamole during a 201Tl myocardial study. Despite aminophylline administration, the patient developed a completed stroke. The mechanism most likely responsible for precipitating this patient's stroke is dipyridamole-induced vascular steal. Although dipyridamole-201Tl myocardial imaging is relatively free of major complications, the morbidity and mortality associated with a cerebrovascular accident is significant. The possibility of precipitating a cerebrovascular accident during dipyridamole-201Tl imaging should be considered in all patients with significant risk factors for stroke before performing a dipyridamole cardiac study.

Cerebrovascular Disorders↗
PubMed1992

Simultaneous measurement of oxygen and dopamine: coupling of oxygen consumption and neurotransmission.

Fast-scan cyclic voltammetry was used to simultaneously measure increases in dopamine concentration and decreases in O2 concentration evoked by brief electrical stimulation (two pulses at 10 Hz) in slices of rat caudate nucleus. Dopamine concentration began increasing immediately after the first pulse and reached a maximum within 200 ms of stimulation. The O2 concentration began to decrease 300-700 ms after onset of stimulus. Responses for both dopamine and O2 were dependent on external Ca2+ and were Cd2+ and tetrodotoxin sensitive. Only the O2 response was sensitive to CN- (0.15 mM). At short times after exposure to 50 microM ouabain, electrically stimulated dopamine overflow was increased by 150% and electrically stimulated changes in O2 concentration were unaffected. Maximum dopamine concentration was increased 28% by sulpiride (2 microM), 78% by L-DOPA (60 microM), 105% by nomifensine (10 microM) and unaffected by nialamide (10 microM). Maximum decrease in O2 concentration was increased by 25% by sulpiride and unaffected by nialamide, L-DOPA, or nomifensine. The decreases in O2 concentration are indicative of increased O2 consumption and are a measure of oxidative energy production evoked by electrical stimulation. The increase in dopamine is due to the release of dopamine balanced by uptake and serves as an indication of neurotransmitter activity. The results indicate that increases in oxidative energy production following electrical stimulation are dependent on external Ca2+ entry through Cd(2+)-sensitive channels. Possible mechanisms for this coupling are discussed.

Animals↗
PubMed1992

Acute renal failure in adults with uncomplicated acute pyelonephritis: case reports and review.

Acute renal failure is a rare complication of acute pyelonephritis in patients who do not have urinary obstruction. Although urinary tract infections are common in adults, pyelonephritis is rarely considered in the differential diagnosis of acute renal failure nor is renal failure considered a likely consequence of bacteriuria. In this review, the cases of acute renal failure caused by acute pyelonephritis that have been reported in the last quarter century are examined. Including two new cases reported, only 12 cases of acute pyelonephritis resulting in acute renal failure were found. Three of these occurred in patients with a solitary kidney. All cases occurred in individuals who had no history of urinary tract infections, and all were caused by Escherichia coli. In several cases, the administration of non-steroidal antiinflammatory drugs contributed to disease. Three cases occurred after catheter-acquired bacteriuria. Acute renal failure is an uncommon but serious consequence of uncomplicated acute pyelonephritis in adults.

Acute Disease↗
PubMed1992

Circulating lipids and minor abnormalities of thyroid function.

OBJECTIVE: We determined the effect of subclinical hyperthyroidism (defined as low circulating TSH with normal serum free T4) and subclinical hypothyroidism (raised serum TSH with normal free T4) on fasting levels of blood lipids. DESIGN: Prospective study of lipid concentrations in patients identified as having abnormal TSH. PATIENTS: Patients were identified in a population screening study of those over 60 years, with persistently low TSH with normal free T4 (n = 27) or high TSH but normal free T4 (n = 57). Patients were matched to controls with normal serum TSH by age, sex and body mass index. MEASUREMENTS: Serum TSH, free T4, free T3, total cholesterol, low density lipoprotein (LDL) cholesterol and high density lipoprotein (HDL) cholesterol. RESULTS: Serum free T4 measurements were significantly higher in those with subclinical hyperthyroidism than in their controls (P < 0.001) and lower in those with subclinical hypothyroidism than in matched controls (P < 0.001). Measurement of fasting lipids in patients and controls revealed a marked (12.2%) reduction in serum total cholesterol in subclinical hyperthyroidism (P < 0.01); no significant difference in fasting lipids between patients with subclinical hypothyroidism and controls was observed. CONCLUSIONS: Differences in free T4 between those with low or high TSH and controls with normal TSH suggest that abnormalities of TSH directly reflect thyroid hormone excess and deficiency. A reduction in cholesterol in those with subclinical hyperthyroidism suggests a direct influence of thyroid hormone excess on lipid metabolism in these patients.

Aged↗
PubMed1992

Dynamic observation of dopamine autoreceptor effects in rat striatal slices.

Fast-scan cyclic voltammetry has been used to measure dopamine (DA) synaptic overflow in slices of rat caudate nucleus induced by electrical stimulation with one-, two-, and 50-pulse, 10-Hz trains. Synaptic overflow in this preparation is shown to be the result of the competing effects of release and cellular uptake. Release caused by all pulses was attenuated by the D2 agonist quinpirole (1 microM). The rapid time response of the measurements (100 ms) allows the autoinhibition induced by endogenous, released DA to be resolved in real time. The concentration of DA released during the second pulse of a train was 58% of that released by the first pulse, an effect that is partially blocked by the addition of 2 microM sulpiride, a D2 antagonist, to the perfusion buffer. DA release during the first stimulus pulse is unaffected by 2 microM sulpiride, suggesting that autoreceptors are not normally occupied in this preparation. Release caused by the third pulse was 14% of the first pulse and also could be partially enhanced by 2 microM sulpiride. The duration of the inhibition of release induced by endogenous DA was estimated by varying the interval between one-pulse stimulations until the overflow of DA induced by the second pulse was equal to that on the first; a half-time of approximately 17 s was found. The addition of picrotoxin (100 microM) and glutamate (10 microM) to the perfusion buffer did not affect stimulated release of DA, although the addition of atropine (100 microM) attenuated overflow for all the trains tested.

Acetylcholine↗
PubMed1992

Clinical evaluation of a rapid parathyroid hormone assay.

Modifications to the incubation conditions of radioimmunoradiometric assay for whole molecule parathyroid hormone (PTH) permit accurate quantification of the hormone in the peripheral circulation within 1 h of sampling. We assessed the assay intraoperatively in 75 patients undergoing parathyroidectomy. Serum PTH concentration declined to less than 20% of its pre-operative value within 20 min of the successful completion of surgery provided that renal function was normal. In patients with chronic renal failure the rate of decline in serum PTH concentration after parathyroidectomy was slower in some cases. In four cases of unsuccessful parathyroidectomy, serum PTH concentration remained above 60% of its preoperative value. Intraoperative monitoring during parathyroidectomy using this rapid PTH assay offers considerable advantages to the surgeon over frozen section.

Adult↗
PubMed1992

Intermediate efficacy mu opioids: examination of their morphine-like stimulus effects and response rate-decreasing effects in morphine-tolerant rats.

The present study examined the effects of morphine, the intermediate efficacy mu opioids (-)-pentazocine, (-)-metazocine, proxorphan, levallorphan, (-)-NANMY (N-allylnormetazocine) and (-)-cyclazocine, and the mu antagonist naloxone 1) in rats responding under a FR (fixed-ratio) 30 schedule before, during and after a chronic morphine regimen, and 2) in rats trained to discriminate 10.0 [10-MS (morphine sulfate)] or 3.0 mg/kg (3-MS) of morphine from saline. Under the FR30 schedule, chronic administration of morphine produced tolerance to morphine's rate-decreasing effects and conferred cross-tolerance to (-)-metazocine, proxorphan and (-)-pentazocine. However, the effects of these intermediate efficacy mu opioids could be differentiated from those of morphine on the basis of their 1) shallow dose-effect curves, and 2) large differences in the degree to which tolerance developed in individual rats. In the drug discrimination procedure, (-)-metazocine, proxorphan and (-)-pentazocine produced high levels of substitution for the 3-MS stimulus and intermediate levels for the 10-MS stimulus. In contrast to the pattern of substitution observed with morphine in the 10-MS group, the effects of these drugs were characterized by 1) shallow dose-effect curves, 2) large individual differences in the lowest dose of each drug that substituted completely for the 10-MS stimulus and 3) the failure to obtain complete substitution for the 10-MS stimulus in all of the rats tested. The behavioral profile obtained with the intermediate efficacy mu opioids (-)-NANM, levallorphan and (-)-cyclazocine was indicative of opioids with intrinsic efficacy lower than that of (-)-pentazocine, (-)-metazocine and proxorphan. Under the FR30 schedule, chronic administration of morphine produced an enhanced sensitivity to the rate-decreasing effects of (-)-NANM and levallorphan but not (-)-cyclazocine. In the drug discrimination procedure, (-)-NANM, levallorphan and (-)-cyclazocine produced high levels of substitution for the 3-MS stimulus and low levels for the 10-MS stimulus. Like naloxone, these drugs produced a dose-related attenuation of the 10-MS stimulus. The results of the present study suggest that the relative order of intrinsic efficacy among the opioids tested is: morphine > (-)-metazocine = (-)-pentazocine = proxorphan > (-)-cyclazocine = levallorphan = (-)-NANM > naloxone.

Animals↗
PubMed1992

Vector specificity of Trypanosoma catostomi and its infectivity to freshwater fishes.

Trypanosoma catostomi was found in 36.2% of 558 white suckers (Catostomus commersoni) from Ontario, Canada. The abundance of Actinobdella inequiannulata was 35% (68 leeches/197 suckers examined for leeches). The susceptibility of 3 species of leeches (Hemiclepsis marginata, Desserobdella phalera, and A. inequiannulata) and 7 species of fishes (C. commersoni, Amia calva, Anguilla rostrata, Ictalurus nebulosus, Oncorhynchus mykiss, Perca flavescens, and Esox lucius) to infection with T. catostomi was examined. Metatrypanosomes were found in the crop and proboscis sheath of 13 of 21 A. inequiannulata and in the crop of 10 of 12 H. marginata and 1 of 21 D. phalera. Only flagellates from A. inequiannulata were infective to C. commersoni. Cultured T. catostomi infected C. commersoni and A. calva but not any other fish species. Laboratory-reared C. commersoni were more susceptible than wild-caught specimens. Cultured Trypanosoma phaleri did not infect its natural host, A. calva. Host specificity should be established experimentally before a specific diagnosis is made. Cultures may be useful in simulating factors that affect development in the vector.

Animals↗
PubMed1991

Effects of immunosuppressive therapy in biopsy-proved myocarditis and borderline myocarditis on left ventricular function.

Twenty patients with decreased left ventricular (LV) function and endomyocardial biopsy-proved myocarditis (9 patients) or borderline myocarditis (11 patients) were studied to determine whether these 2 histologic subsets of patients with inflammatory heart disease differed in their response to a 6- to 8-week course of immunosuppressive therapy. All patients received a regimen of prednisone, 1.0 mg/kg/day, and azathioprine, 1.5 mg/kg/day, followed by repeat endomyocardial biopsy and reevaluation of LV function. LV function improved significantly in the group with borderline myocarditis, as assessed by LV stroke work--end-diastolic volume ratio (0.26 +/- 0.17 to 0.54 +/- 0.31 kg.m.ml-1, p less than 0.02), heart rate corrected velocity of circumferential shortening (0.49 +/- 0.30 to 0.80 +/- 0.29 circ.s-1, p less than 0.05), and LV ejection fraction (0.30 +/- 0.15 to 0.47 +/- 0.13, p less than 0.05). LV end-diastolic and end-systolic volume indexes also decreased significantly from 129 +/- 40 to 94 +/- 38 (p less than 0.05) and 90 +/- 37 to 49 +/- 26 ml (p less than 0.02), respectively. No significant change in these indexes of LV function or volume occurred in the myocarditis group. Whereas salutory improvements in cardiac output and filling pressures were found in both groups, objective improvement in LV function assessed by complementary indexes of contractility was greatest in the borderline myocarditis group. It is concluded that short-term immunosuppressive therapy improves LV contractile function and appears to be associated with regression of ventricular dilatation in patients with borderline myocarditis to a greater extent than patients with myocarditis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Persistent hyperthyrotropinaemia since the neonatal period in clinically euthyroid children.

We describe three children, now aged between 5 and 6 years, with a persistent mild hyperthyrotropinaemia since the neonatal period and normal levels of thyroid hormones. The increased thyroid stimulating hormone concentration is not artefactual and is not caused by antibody interferences. Their growth and development is normal and none has received thyroid hormone replacement. We believe that they have compensated hypothyroidism, and that before the advent of screening for congenital hypothyroidism these children would have presented in mid-childhood with juvenile hypothyroidism.

Child↗
PubMed1991

A case of spontaneous regression of metastatic testicular teratoma.

We report the apparently spontaneous regression of metastatic disease in a young man who had previously undergone orchidectomy for a primary testicular teratoma. Serial serum tumour marker estimations revealed a sharp rise followed by a spontaneous decline in levels in a patient who had requested that chemotherapy be deferred for personal reasons.

Adult↗