Effects of benextramine on the adrenergic inhibition of insulin secretion in isolated rat pancreatic islets

Insulin secretion from isolated rat islets of Langerhans in the presence of 4 mM glucose averaged 2.26 +/- 0.20 (S.E.M.) ng/islet per 90 min and was significantly (P less than 0.001; n = 30) increased to 3.28 +/- 0.21 ng/islet per 90 min by the covalent alpha-adrenoceptor antagonist benextramine (10 microM). Glucose (20 mM) also increased the secretion rate (to 6.24 +/- 6.0 ng/islet per 90 min) but, under these conditions, the response was not further enhanced by benextramine. Clonidine and noradrenaline (1 nM-10 microM) each caused dose-dependent inhibition of glucose-induced insulin secretion which was maximal at 1 microM. Benextramine, when added simultaneously with the agonist, relieved, in a dose-dependent manner, the inhibition of secretion induced by either clonidine or noradrenaline with similar sensitivity. Even after a 30-min preincubation with benextramine the antagonist failed to differentiate between noradrenaline, adrenaline and clonidine with respect to inhibition of insulin secretion. In contrast to its effects on adrenergic responses, short-term treatment with benextramine did not significantly affect muscarinic-cholinergic receptor-mediated 45Ca2+ efflux from rat islets of Langerhans perifused in Ca2+-depleted medium. These data suggest that benextramine does not differentiate between clonidine and noradrenaline in rat islets of Langerhans but that it does show preference for alpha-adrenoceptors in this tissue.

HLA typing in the Hong Kong Chest Service/British Medical Research Council study of factors associated with the breakdown to active tuberculosis of inactive pulmonary lesions

As part of a multifactorial study of the causes of breakdown to active tuberculosis of inactive pulmonary lesions, HLA-A, -B, and -DR typing was performed on 256 Hong Kong Chinese patients and 100 healthy control subjects. Patients were classified into those with smear-positive, active pulmonary tuberculosis (n = 103), those with inactive disease (n = 113), and those with breakdown to active disease after 6 months or more of inactivity (n = 40). Separately, 21 multiple-case families comprising 38 available parents and 93 offspring were examined for HLA haplotype segregation in relation to infection. Results of both studies indicate that among Hong Kong Chinese there is no statistically significant association between HLA and susceptibility to pulmonary tuberculosis.

Benefits of dual chamber pacing in sick sinus syndrome

The effects of DDD (fully automatic) and VVI (ventricular demand) pacing modes on exercise tolerance, symptom diary cards, and Holter monitoring were investigated in a randomised double blind crossover study of 16 patients who had had DDD pacemakers implanted because of frequent syncope. Eight patients presented with sick sinus syndrome and, with one exception, retrograde atrioventricular conduction and eight age and sex matched patients presented with 2:1 or complete atrioventricular block. Maximal symptom limited exercise in those with atrioventricular block was significantly higher after one month of DDD pacing than after VVI pacing. In those with sick sinus syndrome, however, maximal effort tolerance was not significantly different for the two pacing modes. In all but one patient with sick sinus syndrome sinus rhythm developed during exercise in VVI pacing. For both VVI and DDD modes maximal atrial rates were significantly lower in those with sick sinus syndrome. Palpitation and general wellbeing were significantly improved during DDD pacing in the eight patients with sick sinus syndrome. Shortness of breath was improved by DDD pacing in the eight patients with atrioventricular block but not in those with sick sinus syndrome. Holter monitoring showed that sick sinus syndrome patients remained in paced rhythm, either DDD or VVI, for most of the 24 hour period. DDD pacing was better than VVI pacing in sick sinus syndrome with retrograde atrioventricular conduction. Despite their ability to show sinus rhythm and inhibit their pacemakers on exercise patients with sick sinus syndrome are just as likely to have symptomatic benefit from DDD pacing as patients with atrioventricular block.

Total skin electron irradiation for mycosis fungoides: relationship between acute toxicities and measured dose at different anatomic sites

From June 1978 to June 1986, 50 patients with primary and recurrent mycosis fungoides were treated with total skin electron irradiation (TSEI), using the Stanford technique, to a total dose of 3600 cGy. TSEI was used alone, or in combination with low dose total body photon irradiation, or MOPP. Thermoluminescent dosimeter (TLD) measurements of the prescribed skin dose were obtained on twenty patients. The dorsum of the foot was 24% higher. The axillae, the bottom, and the arch of the foot were significantly underdosed. Frequencies of acute toxicities noted at 2000 cGy were: Skin, Grade I-II (RTOG) 80%. Partial epilation: scalp, 100%; eyebrows and at eyelashes, 20%. Nail dystrophy, 48%. Edema: hands and feet, 44%. Bullae: dorsum of feet, 8%; hands, 4%; and 3600 cGy: Skin, grade III 22%. Total epilation: scalp, 66%; eyebrows and eyelashes, 56%. Nail loss, 38%. Edema: hands and feet, 76%. Bullae: dorsum of feet, 34%; hands, 12%. Conjunctivitis, 4%. Large bullae, were more significant on the dorsum of the feet. Severe moist desquamation occurred in eight patients who had ulcerated lesions on initial presentation. Three patients were hospitalized due to ulceration and skin infection. All patients completed treatment after a short to moderate break. No patient developed skin necrosis, or corneal ulceration. No correlation exists between dose level, degree and onset of toxicity with previous chemotherapy or TBI. We conclude that the overall toxicity of TSEI is well tolerated.

Male infertility: diagnosis and treatment

The evaluation of the subfertile male starts with the basic history and physical examination, which often provide indication of probable cause. Aside from analysis of properly collected semen, most cases require very few tests. Etiology can be classified as pretesticular, testicular, and post-testicular. Treatment can be more specific if a definite cause is found. Unfortunately, about 25% of patients are idiopathic, and non-specific treatments generally yield unacceptably low conception rates. Improvement will occur as more becomes known, through animal research and clinical application, about the physiology of spermatogenesis and the pathological processes that can affect it.

High-performance liquid chromatographic method for isolating organic contaminants from tissue and sediment extracts

Interest in the assessment of the anthropogenic contamination of the marine environment has accelerated in recent years. Existing methods to analyze environmental samples (e.g., sediments or tissues) for trace amounts of organic contaminants such as aromatic hydrocarbons and chlorinated compounds are tedious and costly. We report a rapid, efficient high-performance liquid chromatography (HPLC) procedure which uses a size-exclusion column to separate the analytes of interest from interfering compounds in the sample matrix. Analytical results from the HPLC method were, in general, comparable to a gravity-column method which had been used for several years. The HPLC method had several other advantages: improved precision; the ability to monitor chromatographic conditions; the potential for automating analyses; and reduced consumption of solvents and other materials.

The importance of genetics for the optimization of radiation therapy. A hypothesis

There is growing evidence that a fraction of cancer patients, perhaps as high as 15%, is radiation sensitive because of the action of specific genes. It seems likely that in the near future we shall be able to identify these patients by DNA probes. Therefore, we have calculated the impact on radiation therapy of removing these patients and treating the rest more aggressively. In particular, we assumed that the radiation oncologist will treat with an effective therapeutic dose corresponding to a 5% risk of serious normal tissue injury. Our results, in several instances, show a considerable increase in local control when the 5, 10, or 15% of the most radiosensitive patients are removed from the treated group. This is so, even if we assume that the tumor cells, as well as the normal cells, in radiosensitive patients are more radiosensitive than the tumor cells in patients of normal radiosensitivity.

Radiological progression and lung function in silicosis: a ten year follow up study

Chest radiographs and spirometric tests were performed on 81 patients who had silicosis from two granite quarries in 1975, 73 of whom were followed up for two to 10 (mean 7.2) years. Each patient's initial and most recent chest radiographs were assessed independently by three experienced readers, and the yearly declines in forced expiratory volume in one second and forced vital capacity were estimated from two to four (mean 3.45) serial spirometric readings. Estimates of individual dust exposure were based on extensive historical data on hygiene. All but 11 patients were no longer exposed to dust by the start of follow up, but 24 (45%) of 53 patients who had simple silicosis and 11 (55%) of 20 who had the complicated disease showed radiological evidence of disease progression. In patients who had simple silicosis and showed no radiological progression the yearly declines in forced expiratory volume in one second and forced vital capacity were modest (64 ml/year and 59 ml/year, respectively), whereas significantly greater declines in lung function were seen in those who showed radiological evidence of progression (97 ml/year and 95 ml/year, respectively). In addition to radiological progression the previous average dust concentration to which patients had been exposed also influenced declines in both forced expiratory volume in one second and forced vital capacity after allowing for the effects of age, smoking, duration of exposure, history of tuberculosis, initial state of disease, and baseline lung function. The probability of radiological progression was most strongly influenced by the average dust concentration previously exposed to. The progression of simple silicosis is thus accompanied by appreciable declines in lung function and is strongly affected by previous levels of exposure to dust.

A survey of the respiratory health of silica-exposed gemstone workers in Hong Kong

Respiratory symptoms and radiographic and lung function alterations were studied in a cross-sectional survey of gemstone workers in Hong Kong. The study population included a group of grinders, polishers, and buffers who were heavily exposed to dust (principally free silica) and a less exposed group of cutters and carvers. Among all 218 male workers who answered the respiratory questionnaire, heavily exposed workers reported significantly higher prevalence of respiratory symptoms suggestive of mucus hypersecretion. Radiological pneumoconiosis defined as opacities with profusion of 1/0 and above was found in 27% of 157 workers who accepted radiographic and lung function examination. Radiological opacities were significantly related to increasing years of employment in both groups of workers after taking into account age and smoking habits. Decline in forced vital capacity (FVC) was significantly related to increasing years of employment in both groups after allowing for the effects of age, height, and smoking. A modest decline in forced expiratory volume in one second (FEV1) was related to dust exposure which was of borderline statistical significance in polishers and buffers who smoked. Radiological pneumoconiosis did not have an independent effect on lung function when allowance was made for dust exposure.

Field and laboratory studies of the etiology of liver neoplasms in marine fish from Puget Sound

A series of field studies was conducted between 1979 and 1985 in Puget Sound, Washington State, to investigate etiological relationships between prevalences of hepatic neoplasms in bottom-dwelling marine fish species, with emphasis on English sole (Parophrys vetulus), and concentrations of toxic chemicals in sediments and affected fish. Statistically significant (p less than or equal to 0.05) correlations have been found between the prevalences of hepatic neoplasms in English sole and the following parameters: sediment concentrations of aromatic hydrocarbons, and concentrations of the metabolites of aromatic compounds in the bile of affected sole. A significant difference (p less than 0.001) was also found between the relative concentrations of aromatic free radicals in the liver microsomes of English sole with liver lesions compared to sole without liver lesions. Laboratory studies designed to evaluate the etiology of the liver neoplasms in English sole have also yielded evidence that is consistent with the view that high molecular weight aromatic hydrocarbons, e.g., benzo[a]pyrene (BaP), are hepatocarcinogens in English sole. The current status of a series of long-term (up to 18 months) exposures of English sole and rainbow trout (Salmo gairdneri) to selected fractions of Puget Sound sediment extracts, enriched with aromatic hydrocarbons and nitrogen-containing aromatic compounds, and to individual carcinogens (e.g., BaP) is discussed.

The bioavailability of isoniazid, rifampin, and pyrazinamide in two commercially available combined formulations designed for use in the short-course treatment of tuberculosis

The bioavailability of isoniazid, rifampin, and pyrazinamide in 2 combined formulations of the 3 drugs (Rifater) for use primarily in the short-course chemotherapy of tuberculosis has been studied in Chinese patients in Singapore and Hong Kong. One formulation, containing 50 mg isoniazid, 120 mg rifampin, and 300 mg pyrazinamide per tablet is suitable for daily use, whereas the other, containing higher proportions of isoniazid and pyrazinamide, is designed for intermittent treatment, each tablet containing 125 mg isoniazid, 100 mg rifampin, and 375 mg pyrazinamide. Appropriate dosages for the Chinese patients, whose average weight was approximately 50 kg, were 5 and 6 tablets, respectively. Plasma concentrations of the 3 drugs after giving such dosages of the 2 combined formulations were compared in 16 patients, 8 in Singapore and 8 in Hong Kong, by means of a crossover study, with the concentrations obtained when identical doses of the 3 drugs were given using standard separate drug formulations. The concomitant urinary excretions of the drugs and their major metabolites were also estimated. Very similar results were obtained whether the drugs were given as the combined preparations or in their standard separate formulations, demonstrating the excellent bioavailability of all 3 drugs in each of the 2 combined formulations.

Toxic chemicals in sediments and biota from a creosote-polluted harbor: relationships with hepatic neoplasms and other hepatic lesions in English sole (Parophrys vetulus)

High prevalences of idiopathic hepatic lesions, including neoplasms (e.g., hepatocellular carcinomas, cholangiocellular carcinomas) (27%, 20 of 75 fish) and foci of cellular alteration (putative 'preneoplastic' lesions) (44%, 33 of 75 fish), were found in English sole (Parophrys vetulus) exposed to creosote-contaminated sediments in Eagle Harbor, Puget Sound, WA. Sediments from the contaminated region of the harbor contained particularly high concentrations of aromatic hydrocarbons (e.g., benzo[a]pyrene and benz[a]anthracene), and a variety of nitrogen-containing aromatic compounds (e.g., carbazole and acridine). The composition of the aromatic compounds was characteristic of creosote. Dramatically lower concentrations of aromatic compounds were found in sediments from a reference site in which the bottom-dwelling fish examined were free of detectable neoplastic or 'preneoplastic' hepatic lesions. Food organisms in the stomachs of the English sole from Eagle Harbor contained substantially higher concentrations of aromatic hydrocarbons than comparable organisms from the reference site. The concentrations of individual aromatic hydrocarbons in muscle and liver from the Eagle Harbor fish were low; however, high concentrations of metabolites of aromatic compounds were present in the bile. The findings strongly suggest an association between exposure to creosote and the prevalence of hepatic lesions, including neoplasms, in the bottom-dwelling fish, and furthermore support the putative role of aromatic hydrocarbons in liver carcinogenesis in fish.

Toxic chemicals in marine sediment and biota from Mukilteo, Washington: relationships with hepatic neoplasms and other hepatic lesions in English sole (Parophrys vetulus)

High prevalences of idiopathic liver lesions, including 7.5% hepatic neoplasms (e.g., hepatocellular and cholangiocellular carcinomas) and 16.7% foci of cellular alteration (putative preneoplastic hepatic lesions), were found in English sole (Parophrys vetulus) from waters near Mukilteo, a small community on Puget Sound in Washington State. Sediments from the sampling sites contained particularly high concentrations of aromatic hydrocarbons. Substantially lower concentrations of these compounds were found in sediments from another Puget Sound (reference) site in which fish showed no evidence of hepatic neoplasms or foci of cellular alteration. Stomach contents from the fish at Mukilteo contained substantially higher concentrations of the chemicals than did stomach contents of fish from the relatively uncontaminated site. High concentrations of metabolites of aromatic compounds were measured in the bile of fish from Mukilteo. These findings support previously observed relationships between sediment chemicals (e.g., aromatic hydrocarbons) and high prevalences of liver lesions in English sole from Puget Sound. In addition, a dietary route of uptake by English sole of environmental chemicals, including known carcinogens, was documented.

Baroreflex sensitivity measured by the phenylephrine pressor test in patients with carotid sinus and sick sinus syndromes

Baroreflex sensitivity was measured by the heart rate response to the transient rise in blood pressure induced by phenylephrine, in 11 patients with carotid sinus syndrome, 6 patients with sick sinus syndrome and nine age and blood pressure matched controls. Patients with carotid sinus syndrome were divided into those with a hypersensitive carotid sinus reflex manifest as sinus arrest (n = 9) and those with a reflex manifest as atrioventricular block (n = 2). The mean gain of the baroreflex sensitivity was significantly increased (p less than 0.001) in patients with carotid syndrome manifest as sinus arrest (12.7 +/- 5.1 ms . mmg-1) compared to that in patients with sick sinus syndrome (3.8 +/- 2.6 ms . mmHg-1) and controls (4.2 +/- 2.1 ms . mmHg-1). Patients with carotid sinus syndrome manifest as atrioventricular block did not have increased baroreflex sensitivity measured by their sinus node response (2.1 +/- 0.5 ms . mmHg-1). There was significant correlation (p less than 0.001) between the corrected carotid sinus inhibitory response to carotid sinus massage and the measurement of baroreflex sensitivity in the carotid sinus syndrome patients. Patients with carotid sinus syndrome manifest as reflex sinus arrest have an increased gain in baroreflex sensitivity for their age, which is not seen in patients with symptomatic sinoatrial disease. This study provides further evidence of a different mechanism of bradycardiac symptoms in patients with carotid sinus and sick sinus syndromes.

The management of urinary tuberculosis--a logical approach

The chemotherapy of urinary tuberculosis is controversial as far as choice of drug regimen and duration of treatment are concerned. We propose a course of treatment that is tailored to the pathological state of infection and the type of surgical procedure performed. One hundred and ten patients with tuberculous infection were divided into three groups. Group I comprised 27 patients in whom surgery was not necessary; Group II contained 48 patients where ablative surgery was carried out; Group III consisted of 35 patients who underwent reconstructive surgery. Anti-tuberculous drugs (rifampicin, pyrazinamide, isoniazid and ethambutol) were given according to this tailored regimen. Patient compliance and results of treatment were excellent.

Deoxyribonucleic acid (DNA) flow cytometry: a new modality for quantitative analysis of testicular biopsies

Methods currently in use for quantification of spermatogenesis are not widely accepted clinically because they are time-consuming and open to subjective interpretation. This study explores the use of flow cytometry as a rapid and objective modality for quantitative analysis of testis biopsies.

The treatment of urinary tuberculosis

During the last 7 years we treated 92 patients with tuberculosis of the urinary tract. Patients with tuberculous infection were divided into 3 groups according to treatment: group 1--no surgical treatment (18 patients), group 2--ablative surgery (45 patients) and group 3--reconstructive surgery (29 patients). Antituberculous drugs, consisting of rifampin, pyrazinamide, isoniazid and ethambutol, were given according to the severity and extent of the infection process. The results of medical and surgical treatment were most gratifying. Surgical morbidity was low and there was no immediate mortality.

Sustained improvement in exercise tolerance following physiological cardiac pacing

Fifty-three patients have received 'physiological' pacemakers, 37 with atrioventricular (AV) block having atrial synchronous units (VAT or VDD) implanted and the remaining 16 patients with both AV block and sick sinus syndrome having 'universal' (DDD) pacemakers. Effort tolerance was assessed by serial bicycle ergometry and in 16 patients direct comparisons between ventricular pacing and atrial synchronous pacing could be made acutely. Physiological pacemakers were found to increase maximum effort tolerance by 43% compared to pre-pacing values (P less than 0.01). The increase was sustained over a mean of 33 months post pacing. The atrial synchronous mode increased maximum effort tolerance by 34% acutely compared to ventricular inhibited pacing. Dual chambered 'physiological' pacemakers represent a significant therapeutic advance over standard ventricular inhibited pacemakers.

The role of rate hysteresis pacing in the hypersensitive carotid sinus syndrome

The ability of rate hysteresis programming with the escape interval longer than the automatic interval to reduce the hypotensive response to carotid sinus massage at the onset of ventricular pacing was studied in six patients paced for carotid sinus syndrome. Rate hysteresis significantly reduced this hypotensive response and abolished spontaneous symptoms in two patients and symptoms reproduced by carotid sinus massage in four patients.

Randomised controlled trial of physiological and ventricular pacing

Thirteen patients have completed a randomised double blind cross over study to compare the effects of chronic ventricular and atrial synchronous pacing on exercise capacity and symptoms. Maximal symptom limited exercise was significantly increased after one month of atrial synchronous pacing compared with ventricular pacing. Symptomatic assessment (by diary card and monthly symptom scores) of "shortness of breath", "palpitation", and "general well-being" was significantly improved during the physiological pacing mode. Atrial synchronous pacing has been shown to be superior to ventricular pacing.

Physiological benefits of atrial synchrony in paced patients

Over a five-year period, hemodynamic exercise capacity studies and a randomized controlled trial have been performed in a total of 50 patients. DVI vs. VVI pacing showed an increase in stroke work index (P less than 0.005) and a fall in left ventricular filling pressure (P less than 0.05) in 17 patients. VDD/DDD pacing vs. VVI showed an exercise capacity benefit in 44 patients (P less than 0.01) including 8 patients with sinus node disease and a lower peak heart rate (P less than 0.02). Maintenance of benefit was also shown of VDD/DDD pacing in the longer term (13 months) vs. acute (P - NS). The controlled trial VDD/DDD vs. VVI showed benefit in shortness of breath (P less than 0.01) and general well being (P less than 0.01). It is concluded that atrial synchronous ventricular pacing (VDD/DDD) is the mode of choice in suitable patients.

Carotid sinus syncope treated by pacing. Analysis of persistent symptoms and role of atrioventricular sequential pacing

Seventy patients have been paced for carotid sinus syndrome over four years. Twelve patients had persistent symptoms despite adequate ventricular pacing. Patients with persistent symptoms were found to have a significant vasodepressor response, a significant hypotensive response to ventricular pacing (pacemaker effect), and a severe hypotensive response to carotid sinus massage with introduction of ventricular pacing, which reproduced symptoms in all patients. A group of 14 asymptomatic paced carotid sinus patients was found to have a significantly lower vasodepressor response, pacemaker effect, and combined vasodepressor response plus pacemaker effect than the group with persistent symptoms. Atrioventricular sequential pacing was shown to eliminate the hypotensive effect of ventricular pacing and is considered to be the treatment of choice for patients with carotid sinus syndrome who have both cardioinhibitory and significant vasodepressor responses.