Passive smoking by self report and serum cotinine and the prevalence of respiratory and coronary heart disease in the Scottish heart health study

STUDY OBJECTIVE

To explore the relationship between self reported environmental tobacco smoke exposure (or passive smoking), the serum cotinine concentration, and evidence of respiratory or coronary disease in men and women who have never smoked.

DESIGN

Cross sectional random population survey identifying disease markers and relating them to measures of passive smoking. Disease markers were previous medical diagnoses, response to standard symptom questionnaires, and electrocardiographic signs.

SETTING

Samples of men and women aged 40-59 years drawn from general practitioner lists in 22 local government districts of Scotland, between 1984 and 1986.

PARTICIPANTS

A total of 786 men and 1492 women who reported never having smoked tobacco, and who had serum cotinine concentrations below 17.5 ng/ml, the cut off point for smoking "deceivers", took part.

RESULTS

Fewer than one third of never smokers reported no recent exposure to environmental tobacco smoke and the same proportion had no detectable cotinine. Women had lower cotinine values than men but reported more exposure to smoke. The correlation between the measures of exposure was poor. Self-reported exposure showed strong, statistically significant, dose response relationships with respiratory symptoms and with the coronary disease markers. These relationships were weak or absent for serum cotinine, except for diagnosed coronary heart disease. Here the dose response gradient was as strong as that for self report, with an odds ratio of 2.7 (95% CI 1.3, 5.6) for the highest v the lowest exposure group, adjusted for age, housing tenure, total cholesterol, and blood pressure, and not explained by fibrinogen.

CONCLUSIONS

The validity of different measures of tobacco smoke exposure needs further investigation. The gradient of diagnosed coronary heart disease with both self reported exposure and serum cotinine was, however, surprisingly strong, statistically significant, and unexplained by other factors. These findings reinforce current policies to limit passive tobacco smoke exposure.

Effects of aging and dietary protein intake on uninephrectomized geriatric dogs

Thirty-one clinically normal Cocker Spaniels, Miniature Schnauzers, and Doberman Pinschers (28 female, 3 male) 7 to 8 years old were uninephrectomized (month -2) to increase the risk of renal damage associated with reduction of renal mass. Two diets, differing principally in protein concentration, were used to test the hypothesis that high dietary protein intake causes renal damage in aging dogs. For 2 months after uninephrectomy, all dogs were fed diet A (18% protein). After glomerular filtration rate (GFR) was measured (month 0), 16 dogs were assigned to group A and were fed diet A for an additional 48 months. The other 15 dogs were assigned to group B, and were fed diet B (34% protein) for the subsequent 48 months. At 6-month intervals, GFR and urine protein-to-creatinine ratio (UP/C) were determined. At 48 months, terminal studies were done, survivors were euthanatized, and tissues were examined. Of 16 dogs in group A, 10 survived, compared with 13 of 15 in group B. Among survivors, a significant difference in GFR was not found between groups A and B, and decrease in GFR was not evident with time in either group. At 48 months, oral administration of casein caused minor acute effects on GFR and renal plasma flow in dogs of groups A and B. The UP/C values increased significantly (P = 0.001) from baseline values, but the increase was not progressive. The UP/C values were not affected by diet. Some dogs in both groups developed UP/C > 1.0.(ABSTRACT TRUNCATED AT 250 WORDS)

The imidazoline site involved in control of insulin secretion: characteristics that distinguish it from I1- and I2-sites

1. The nature of the binding site mediating the insulin secretagogue activity of certain imidazoline compounds remains unclear and the pharmacology of the I1- and I2-imidazoline sites, described in many tissues, does not correlate with the observed responses to imidazolines in islets. In the present paper, we describe further results which support the concept that the islet imidazoline site may represent a novel subtype of imidazoline receptor. 2. Culture of rat isolated islets in the presence of imidazoline secretagogues (either efaroxan or phentolamine) resulted in loss of responsiveness on subsequent re-exposure to these agents. However, culture of islets with either idazoxan or UK14,304 (imidazoline ligands that do not stimulate insulin secretion) did not lead to any loss of response when the islets were subsequently exposed to efaroxan. By contrast, islets cultured with UK14,304 (a potent alpha 2-adrenoceptor agonist), displayed loss of sensitivity to noradrenaline, consistent with down-regulation of alpha 2-adrenoceptors. 3. In order to characterize the imidazoline site further, radioligand binding studies were performed in membranes from RINm5F insulinoma cells using [3H]-RX821002, an imidazoline insulin secretagogue that does not interact significantly with imidazoline sites in other tissues. [3H]-RX821002 labelled alpha 2-adrenoceptors with high affinity (2.01 +/- 0.7 nM) but also labelled a second, non-adrenoceptor site with much lower affinity. 4. Under conditions of alpha 2-adrenoceptor blockade (in the presence of adrenaline), efaroxan displaced [3H]-RX821002 binding to the low affinity site, in a dose-dependent manner. Competition studies employing additional imidazoline compounds of varying secretagogue activity revealed that the pharmacological profile of the low affinity site correlates well with that observed in secretion experiments.5. The results obtained from the down-regulation experiments with isolated islets and from the radioligand binding studies suggest that the low affinity [3H]-RX821002 binding site may represent the functional receptor responsible for the secretagogue activity of imidazoline compounds in the endocrine pancreas and that it has a pharmacological profile distinct from those of I,- and 12-sites.

Inherited ventricular arrhythmias and sudden death in German shepherd dogs

OBJECTIVES

This report describes a unique group of German shepherd dogs with inherited ventricular arrhythmias and sudden death. Before death, these dogs have no evidence of cardiovascular failure.

BACKGROUND

There are few spontaneous animal models of sudden death that permit intensive investigation.

METHODS

To determine the temporal evolution of ventricular arrhythmias and to characterize the syndrome of sudden cardiac death in these dogs, 24-h ambulatory electrocardiographic (ECG) monitoring, echocardiograms, electrophysiologic testing and breeding studies were conducted.

RESULTS

The 24-h ambulatory ECGs from dogs that died showed frequent ventricular arrhythmias with rapid polymorphic ventricular tachycardia (rates > 480 beats/min). Affected dogs had a window of vulnerability for arrhythmias, with the highest incidence and severity of arrhythmias between 20 to 30 and 40 to 50 weeks of age. Affected dogs that died did not have prolongation of the QT interval over a spectrum of heart rates compared with unaffected dogs. The clinical arrhythmia was not induced in dogs during programmed electrical stimulation. Severely affected dogs monitored > 5 years did not develop any evidence of heart failure or cardiomyopathy, and no histopathologic abnormalities existed. Seventeen dogs died suddenly (age 4 to 30 months) and were either 1) found dead at first observation in the morning (n = 8), 2) observed to die during sleep (n = 4), 3) observed to die while resting after exercise (n = 3), or 4) observed to die during exercise (n = 2). All sudden deaths occurred between the end of September and April, with most (n = 11) during January and February.

CONCLUSIONS

The cause of the inherited severe ventricular arrhythmias and sudden death in these young German shepherd dogs is still undetermined. A purely arrhythmic disorder is supported by the lack of cardiac pathology. Moreover, the window of vulnerability to ventricular arrhythmias and the age and circumstances of death invite speculation about the role of the autonomic nervous system.

Failure of cigarette smoking to explain international differences in mortality from chronic obstructive pulmonary disease

STUDY OBJECTIVE

The study aimed to explain international differences in rates and trends of chronic obstructive pulmonary disease (COPD) using two measurements of cigarette smoking, the major risk factor for this disease.

DESIGN

Mortality data for COPD were obtained from the World Health Organisation for 31 countries from 1979 to 1988. Smoking data were obtained for most countries. COPD rates were compared to the percentage of current smokers and past levels of cigarette consumption. COPD trends were compared to past consumption trends.

MAIN RESULTS

In men, Romania had the highest COPD mortality and Greece the lowest throughout the period. English speaking countries occupy most of the other top positions, and southern European countries and Japan the low positions. Women show a similar ranking to men (r = 0.75; p < 0.01 (1988)). Mortality rates in men are, in general, two to four times those in women. Most countries show either a decrease or no change in COPD mortality over the period. In women the opposite is true--no clear relationships are seen when comparing rates and trends of COPD with measures of smoking.

CONCLUSION

This failure to explain international COPD differences suggests that national data on COPD may be unreliable or national cigarette smoking data are inadequate, or both.

Cervical radiculopathy treated by infusion of epidural analgesics in homebound patients

STUDY OBJECTIVE

To determine the efficacy and safety of administering low-dose analgesic infusions through cervical epidural catheters.

DESIGN

Retrospective review of medical records.

SETTING

Community hospital.

PATIENTS

14 ambulatory adult patients with chronic cervical radiculopathy due to posttraumatic or osteoarthritic degenerative disk disease persisting after steroid epidural blocks.

INTERVENTIONS

42 catheters were inserted into the cervical epidural space and infused with low-dose fentanyl-bupivacaine mixtures continuously for 2 to 17 days. To prevent side effects, the optimal dose was reached by upgrade adjustments. After catheter insertion, patients were observed for 6 to 21 days for dose adjustment, then discharged home and followed by homecare nurses. After removal of catheters, patients were followed for 8 to 10 days. If pain intensity returned to control levels, other treatment was initiated.

MEASUREMENTS AND MAIN RESULTS

After each catheter treatment, pain intensity was reduced in 79% of the cases. Upon completion of the therapy, 5 patients had 50% to 75% of their pain reduced. Eight patients experienced 75% or more reduction of their original pain. The most common complications were nausea (35.7%) and pruritus (27%). One case of cellulitis was treated with antibiotics. There were no instances of respiratory compromise.

CONCLUSIONS

Patients with chronic persistent cervical radiculopathy pain were effectively treated with infusion of analgesics through epidural catheters for 2 to 17 days while they were at home.

Prevalence of chronic cough and phlegm among male cigar and pipe smokers: results of the Scottish Heart Health Study

BACKGROUND

Previous studies investigating the effect of cigar or pipe smoking on the occurrence of chronic cough and chronic phlegm have reported prevalences among cigar and pipe smokers lying between those of non-smokers and current cigarette smokers. This study uses data on previous cigarette consumption, current cigar or pipe consumption, and biochemical markers of smoking to provide a detailed analysis of chronic cough and chronic phlegm among cigar and pipe smokers.

METHODS

A total of 10,359 men and women aged 40-59 years were sampled for the Scottish Heart Health Study between 1984 and 1986. Prevalence of chronic cough and chronic phlegm among male cigar and pipe smokers (non-cigarette smokers) was compared with those who had never smoked, between ex-smokers of cigarettes and those who had never smoked cigarettes, between cigar-only and pipe-only smokers, and by cigar or pipe consumption levels.

RESULTS

In all, 463 ex-smokers of cigarettes and 154 who had never smoked cigarettes were cigar or pipe smokers; 1080 had never smoked any form of tobacco. Ex-cigarette smokers smoked and inhaled more than those who had never smoked cigarettes. Among the ex-cigarette smokers, cigar or pipe smokers had 1.63-1.71 times the prevalence of both chronic cough and chronic phlegm than those who had never smoked (1.31-1.36 among cigar only smokers; 2.23-2.84 among pipe only smokers). A strong positive dose-response effect was found between the prevalence of symptoms and cigar or pipe consumption.

CONCLUSIONS

Cigar and pipe smokers have a higher prevalence of chronic cough and phlegm than those who have never smoked, and the difference is more marked in pipe-only smokers than in cigar-only smokers. Both categories show a positive dose-response effect. Among cigar and pipe smokers, ex-cigarette smokers have a higher prevalence of symptoms than those who have never smoked cigarettes, which may be because they inhale more or may be attributable to previous cigarette smoking.

Antagonism of the stimulatory effects of efaroxan and glibenclamide in rat pancreatic islets by the imidazoline, RX801080

1. The imidazoline alpha 2-adrenoceptor antagonist, efaroxan, stimulates insulin secretion from rat isolated islets and antagonizes the ability of diazoxide to inhibit glucose-induced insulin secretion. These effects result from closure of ATP-sensitive potassium channels although the mechanisms involved have not been elucidated. 2. In the present work, we have examined the effects of a close structural analogue of efaroxan, RX801080, in rat isolated islets of Langerhans. RX801080 was found to be ineffective as a stimulator of insulin secretion and did not prevent the inhibition of insulin secretion mediated by diazoxide. 3. RX801080 acted as an antagonist of the actions of several imidazolines (efaroxan, phentolamine and midaglizole) in rat islets. It dose-dependently inhibited the ability of efaroxan to antagonize the effects of diazoxide in islets and also completely inhibited the direct stimulation of insulin secretion mediated by efaroxan. 4. RX801080 also antagonized the effects of the non-imidazoline, ATP-sensitive potassium channel blocker, glibenclamide, in rat islets. It inhibited both the capacity of glibenclamide to stimulate insulin secretion and the ability of glibenclamide to overcome the inhibitory effects of diazoxide in rat islets. 5. Antagonism of glibenclamide responses by RX801080 was not due to inhibition of binding of the sulphonylurea to its receptor on the pancreatic beta-cell. 6. The results suggest that imidazoline compounds and sulphonylureas interact with distinct binding sites on islet cells, but that these sites can interact functionally to control islet cell ATP-sensitive potassium channel activity and insulin secretion.

Delayed hypersensitivity testing as a clinical measure of cell-mediated immunity in the cat

The purposes of this study were to examine the cell-mediated immune response of the normal cat to the modified live feline viral rhinitis, calicivirus, and parvovirus (FVRCP) vaccine (Felocell CVR, Norden, Lincoln, NE), and to evaluate the intradermal skin test as a clinical measure of the immune response of cats. Vaccine and diluent were injected intradermally on the dorsal pinna of 34 normal adult cats. Skin thickness measurements, lymphocyte counts, and Concanavalin A mitogenesis indices were evaluated in 18 of these cats. Skin biopsies were obtained in 16 cats. In normal cats, the FVRCP vaccine induced a delayed hypersensitivity response characterized by a mononuclear infiltrate most pronounced at 72 h. Five cats with either feline leukemia (FeLV) or feline immunodeficiency virus (FIV) were tested and had a significantly reduced response to the skin test. The skin test provides a clinically useful method of evaluating immune function in cats and may be useful in development of a prognostic index.

beta-Hexosaminidase isozymes from cells cotransfected with alpha and beta cDNA constructs: analysis of the alpha-subunit missense mutation associated with the adult form of Tay-Sachs disease

In vitro mutagenesis and transient expression in COS cells has been used to associate a missense mutation with a clinical or biochemical phenotype. Mutations affecting the alpha-subunit of beta-hexosaminidase A (alpha beta) (E.C.3.2.1.52) result in Tay-Sachs disease. Because hexosaminidase A is heterodimeric, analysis of alpha-chain mutations is not straightforward. We examine three approaches utilizing previously identified mutations affecting alpha-chain folding. These involve transfection of (1) the alpha cDNA alone; (2) a beta cDNA construct encoding a beta-subunit substituted at a position homologous to that of the alpha-subunit, and (3) both alpha and beta cDNAs. The latter two procedures amplified residual activity levels over that of patient samples, an effect not previously found with mutations affecting an "active" alpha Arg residue. This effect may help to discriminate between protein-folding and active-site mutations. We conclude that, with proper controls, the latter method of cotransfection can be used to evaluate the effects and perhaps to predict the clinical course of some alpha-chain mutations. Using this technique, we demonstrate that the adult-onset Tay-Sachs mutation, alpha Gly --> Ser269, does not directly affect alpha beta dimerization but exerts an indirect effect on the dimer through destabilizing the folded alpha-subunit at physiological temperatures. Two other alpha mutations linked to more severe phenotypes appear to inhibit the initial folding of the subunit.

Hepatic lobe torsion as a cause of colic in a horse

A 14-year-old Arabian gelding was examined for colic. An exploratory celiotomy was subsequently performed and the left lobe of the liver was found to be twisted. The lobe was resected using a TA-90 surgical stapling instrument. Histologic examination of the resected liver indicated portal vein and sinusoid dilation and congestion with blood. There were focal areas of necrosis and bacterial cocci and rods throughout the section. The histologic findings were consistent with hepatic lobe torsion. After surgery, the horse was treated with broad spectrum antibiotics, anti-inflammatory drugs, heparin, and intravenous fluids. The horse recovered without complications, although serum liver enzymes remained elevated for more than 1 week after surgery. Seven months after surgery the horse showed no adverse affects from the disease.

Coffee and tea consumption and the prevalence of coronary heart disease in men and women: results from the Scottish Heart Health Study

STUDY OBJECTIVES

The aim was to determine if there was a relationship between coffee or tea consumption and the prevalence of coronary heart disease in Scotland.

DESIGN

The relationship between self reported coffee and tea consumption and the prevalence of coronary heart disease (history, symptoms, or electrocardiographic evidence) was investigated using multiple logistic regression analysis in the Scottish Heart Health Study (SHHS), a cross sectional study.

SETTING

Twenty two Scottish districts were surveyed for the SHHS between 1984 and 1986.

SUBJECTS

A total of 10,359 men and women aged 40-59 years were studied.

MEASUREMENTS AND MAIN RESULTS

Of the 9740 subjects who were assigned a category, 21.8% (2122) were classified as having indications of coronary heart disease. Men and women were combined in the odds ratio analysis because they showed almost identical patterns in the prevalence of coronary heart disease across the coffee and tea quarters (grouped according to consumption). Those who did not drink coffee had a significantly higher (p < 0.05) prevalence of coronary heart disease than the three groups for coffee drinkers. Adjustments for risk factors including cigarette smoking, total blood cholesterol, and diastolic blood pressure did not remove the significance of the odds ratios. There was a positive dose-response effect between tea consumption and coronary heart disease which was removed after adjustment for various risk factors.

CONCLUSIONS

These findings do not support a positive relationship between coffee or tea consumption and coronary heart disease in this British study where most coffee consumed is instant coffee.

Heterogeneity of hypertrophy in feline hypertrophic heart disease

Eighty-six cats with non-dilated left ventricular myocardial hypertrophy were studied retrospectively. Cats were categorized by two-dimensional echocardiography as having symmetric ventricular hypertrophy (Type I), asymmetric with predominant septal thickening hypertrophy (Type II), and asymmetric hypertrophy with predominant free-wall thickening (Type III). The distribution of hypertrophy was judged subjectively and objectively. Subjective and objective results were similar (P = 0.03) although overlap existed between groups. Morphologic patterns (Types I, II, and III) were compared with breed, age, sex, heart rate, percent fractional shortening, left atrial size, serum creatinine concentration, and the presence (yes/no) of pleural effusion, pulmonary edema, pericardial effusion, heart murmur, dyspnea, thromboembolism, hyperthyroidism, and being alive at the time of study. Interventricular septal thickness, left ventricular free wall thickness, percent fractional shortening, and left atrial size additionally were compared to 3-month survival. Cats with Type III hypertrophy were more likely to experience thromboembolism than cats with Type II hypertrophy (P = 0.05) and cats with Type I hypertrophy were more likely to have heart murmurs than cats with Type III (P = 0.02). No other significant associations were found in comparison to pattern of hypertrophy. Both left atrial size and percent fractional shortening significantly correlated with 3-month survival (P < 0.001 for each). The degree of interventricular septal wall thickness was associated with 3-month survival (P = 0.02) when known hyperthyroid cats were excluded from the study group, while left ventricular free wall thickness consistently was not associated with survival.(ABSTRACT TRUNCATED AT 250 WORDS)

Nutrient intake by duration of ex-smoking in the Scottish Heart Health Study

Information on current-, never- and ex-smokers (including duration of cessation) was obtained in a cross-sectional survey of risk factors for coronary heart disease (CHD), the Scottish Heart Health Study. Diet was also assessed by food frequency questionnaire in a total of 4265 men and 4770 women. Nutrient intakes were computed by sex and smoking group and, according to their diet, the ex-smokers were categorized as current- or never-smokers using discriminant analysis techniques. The current- and five ex-smoking groups differed negligibly in past smoking characteristics. Energy-adjusted intake of polyunsaturated fat, fibre and the antioxidant vitamins were lowest in current-smokers, and for men, intakes increased progressively with duration of ex-smoking to reach the level of never-smokers. In a similar manner, energy, sugar and alcohol decreased with duration of ex-smoking. Fewer trends were observable for women, and the diets of ex-smokers more immediately resembled that of never-smokers. Discriminant analysis for the combined nutrients correctly categorized 72 and 69% of male, and 66 and 65% of female current- and never-smokers respectively. By 4 years of smoking cessation the general dietary pattern of ex-smokers was similar to never-smokers for both sexes. Whether this represents a change in diet over time or a cohort effect is unclear, but the results do suggest that the apparent healthier diet of ex-smokers may contribute to their reduction in CHD risk compared with life-long current-smokers.

Stimulation of insulin secretion by imidazoline compounds is not due to interaction with non-adrenoceptor idazoxan binding sites

1. The potency of interaction of several imidazoline compounds with non-adrenoceptor idazoxan binding sites (NAIBS) in rat liver membranes was compared with their ability to alter insulin secretion from rat pancreatic islets. 2. NAIBS could be labelled specifically with [3H]-idazoxan in both rat liver membranes and in rat islet homogenates. Liver binding sites exhibited a KD for [3H]-idazoxan of 24 nM and a Bmax of 264 fmol mg-1 protein. 3. Binding of [3H]-idazoxan to NAIBS in rat liver membranes was displaced effectively by unlabelled idazoxan (IC50 0.1 microM) and by UK14304 (IC50 0.5 microM). However, two other imidazoline compounds efaroxan and RX821002, which are related in structure to idazoxan, were much less effective as displacers. 4. In insulin secretion experiments, the ATP-sensitive potassium channel agonist diazoxide (250 microM) was able to suppress the rise in insulin secretion induced by 20 mM glucose. Both efaroxan and RX821002 (100 microM) antagonized the inhibitory effect of diazoxide on glucose-induced insulin secretion. By contrast, neither idazoxan (100 microM) nor UK14304 (50 microM), was able to overcome significantly the inhibitory effect of diazoxide. 5. The ability of 100 microM efaroxan to antagonize the suppression of insulin secretion mediated by diazoxide, was not prevented by idazoxan (up to 100 microM) or by UK14304 (up to 50 microM). 6. The results indicate that the stimulatory effects of imidazoline compounds on insulin secretion are not due to interaction with NAIBS similar to those present in rat liver.

Stimulation of insulin secretion by the imidazoline alpha 2-adrenoceptor antagonist efaroxan is mediated by a novel, stereoselective, binding site

We have studied the stereospecificity of three responses mediated by the alpha 2-antagonist efaroxan in rat islets of Langerhans. alpha 2-Adrenergic inhibition of insulin secretion was relieved most effectively by the (+) enantiomer. In contrast, direct stimulation of insulin secretion and antagonism of the inhibitory effects of diazoxide were both preferentially mediated by the (-) enantiomer. Culture of islets in the presence of efaroxan resulted in loss of responsiveness to subsequent re-addition of the drug. On the basis of these results we propose the existence, in islets, of a novel 'non-adrenergic' binding site at which efaroxan acts as an agonist.

Characterization of two HEXB gene mutations in Argentinean patients with Sandhoff disease

Beta-hexosaminidase A (beta-N-acetyl-D-hexosaminidase, EC 3.2.1.5.2) is a lysosomal hydrolase composed of an alpha- and a beta-subunit. It is responsible for the degradation of GM2 ganglioside. Mutations in the HEXB gene encoded beta-subunit cause a form of GM2 gangliosidosis known as Sandhoff disease. Although this is a rare disease in the general population, several geographically isolated groups have a high carrier frequency. Most notably, a 1 in 16-29 carrier frequency has been reported for an Argentinean population living in an area contained within a 375-km radius from Córdoba. Analysis of the genomic DNA of two patients from this region revealed that one was homozygous for a G to A substitution at the 5' donor splice site of intron 2. This mutation completely abolishes normal mRNA splicing. The other patient was a compared of the intron 2 G-->A substitution and a second allele due to a 4-bp deletion in exon 7. The beta-subunit mRNA of this allele is unstable, presumably as a result of an early stop codon introduced by the deletion. Two novel PCR-based assays were developed to detect these mutations. We suggest that one of these assays could be modified and used as a rapid screening procedure for 5' donor splice site defects in other genes. These results provide a further example of the genetic heterogeneity that can exist even in a small geographically isolated population.

Fatal toxoplasmosis in domestic rabbits in the USA

Three rabbits from two sources died after an acute illness characterized by fever, lethargy and diarrhea in one rabbit and no clinical signs in two rabbits. The most striking lesion in all three rabbits was foci of necrosis of the spleen and liver associated with massive presence of multiplying Toxoplasma gondii tachyzoites. The diagnosis was confirmed by specific staining with anti-T. gondii serum in an avidin-biotin complex immunohistochemical stain.

Two small deletion mutations of the HEXB gene are present in DNA from a patient with infantile Sandhoff disease

Lysosomal beta-hexosaminidase (EC 3.2.1.52) occurs as two major isozymes hexosaminidase A (alpha beta) and B (beta beta). The alpha subunit is encoded by the HEXA gene and the beta subunit by HEXB gene. Defects in the alpha or beta subunits lead to Tay-Sachs or Sandhoff disease, respectively. While many HEXA gene mutations have been reported only three HEXB gene mutations are known. We report the characterization of two rare HEXB mutations present in genomic DNA from a single fibroblast cell line, GM203, taken from a patient with the infantile form of Sandhoff disease. The first is a single base pair deletion in exon 7 changing the codon for Gly-258, GGA, to GA and the second, a two base pair deletion in exon 11 changes the codons for Arg-435/Val-436, AGA/GTC, to AGTC. Each mutation produces a frame shift in the affected allele that results in a premature stop codon 17 or 20 codons downstream, respectively. These mutations also result in the inability to detect beta-mRNA by Northern blot analysis of total mRNA. These data are consistent with the idea that the severe infantile form of Tay-Sachs or Sandhoff disease is associated with a total lack of residual hexosaminidase A activity.

Changes in linoleic acid during follicular development and inhibition of spontaneous breakdown of germinal vesicles in cumulus-free bovine oocytes

The fatty-acid composition of follicular fluid from small and large developing follicles was analysed and the effects of saturated and unsaturated fatty acids on spontaneous breakdown of germinal vesicles were investigated. Fatty acids were bound to bovine serum albumin and cultured with oocytes at 100 mumol/l. Linoleic acid (18:2) was the only fatty acid tested that significantly inhibited breakdown of germinal vesicles (P less than 0.01). The effect was dose-dependent and was greatest at 50 mumol fatty acid/l (% breakdown of control, 81.1 +/- 6.8 vs. 50 mumol linoleic acid/l, 35.4 +/- 7.3; P less than 0.02). Linoleic acid was the major fatty acid, constituting about a third of the total fatty acid in the follicular fluid; followed by 18.9 +/- 1.0% and 16.9 +/- 1.3% oleic acid (18:1) in small and large follicles, respectively. Saturated fatty acids accounted for less than 30% of the total fatty acid composition. There was a marked absence of tetraenoic acids in small and large follicles. Proportions of linoleic acid were significantly lower in follicular fluid from large follicles (31.1 +/- 1.2% of total fatty acid) than from small follicles (34.8 +/- 0.7% of total fatty acid) (P less than 0.05) and there was a significant inverse correlation between follicle diameter and percentage of linoleic acid in the follicular fluid (r = -0.6966; P less than 0.05). There was no significant alteration in any other fatty acid during follicular development.(ABSTRACT TRUNCATED AT 250 WORDS)

Cigarette tar content and symptoms of chronic bronchitis: results of the Scottish Heart Health Study

STUDY OBJECTIVE

The aim was to determine if there was a relationship between cigarette tar yield and rates of chronic cough and chronic phlegm.

SETTING

22 districts across Scotland were used for the Scottish Heart Health Study (SHHS) which was conducted between 1984 and 1986 and from which the data for this analysis were obtained.

SUBJECTS

10,359 men and women aged 40-59 years were studied. Of these, 2801 current cigarette smokers whose brand of cigarette smoked was known were selected.

MEASUREMENTS AND MAIN RESULTS

Data on self reported smoking habits and prevalence of chronic cough and chronic phlegm were obtained from the SHHS. Tar yield was divided into three groups: low (less than or equal to 12 mg/cigarette); middle (13-14 mg/cigarette); high (greater than or equal to 15 mg/cigarette). The average tar yield consumed per person was 13.2 mg/cigarette. Women in the middle and high tar groups had smoked for longer and had significantly higher breath carbon monoxide levels, serum thiocyanate levels, serum cotinine levels, and daily cigarette consumption than the women in the low tar group. This pattern was not seen in men for any of these five smoking variables. Rates of chronic cough and chronic phlegm were higher with higher tar yield of cigarettes smoked for women (low tar v high tar: p less than 0.001) but not for men. Daily cigarette consumption and the number of years of smoking were the most significant risk factors for chronic cough and chronic phlegm for both men and women. Tar was still a significant risk factor (p less than 0.05) for women after controlling for these two risk factors and social class.

CONCLUSIONS

Both sexes show strong effects of daily cigarette consumption and years of smoking on respiratory symptoms; women show an additional effect of cigarette tar content while men do not. The spread of tar yield in both sexes was small but there were more women on low tar cigarettes and this may have enabled a weak effect of tar to be seen better in them. On the other hand, tar level in women was confounded with other factors. Statistical methods of controlling for this may not have removed this confounding completely.

Active arginine residues in beta-hexosaminidase. Identification through studies of the B1 variant of Tay-Sachs disease

Lysosomal beta-hexosaminidase (EC 3.2.1.52) occurs as two major isoenzymes, hexosaminidases A (alpha beta) and B (beta beta). The alpha- and beta-subunits are encoded by the HEXA and HEXB genes, respectively. Extensive homology in both the gene structures and deduced primary sequences demonstrate their common evolutionary origin. Defects in the alpha- or beta-subunits lead to Tay-Sachs of Sandhoff disease, respectively. The B1 variant of Tay-Sachs disease is characterized by an unusual phenotype. Patient samples contain both isoenzymes; however, hexosaminidase A lacks activity toward alpha-specific substrates. In a previous report, we analyzed the biochemical consequences of an Arg178----His substitution in the alpha-subunit, causing the B1 phenotype, by in vitro mutagenesis of the homologous codon for Arg211 in the beta-subunit to produce His. We found that the substitution did not affect dimer formation or cellular targeting but caused a near total loss of activity toward a common alpha- and/or beta-substrate. Additional effects were also noted that suggested a perturbation had occurred to the protein's secondary structure. In this report, we investigate further the role of Arg in the catalysis of hexosaminidase substrates. The introduction of more or less conservative amino acid substitutions at the beta-Arg211 site were evaluated in terms of their effects on the protein's catalytic activity and susceptibility to the arginine-specific reagents and on its stability and rate of maturation in the cell's lysosome. These data demonstrate that the changes in the in vivo stability and rate of maturation, previously noted with the Arg211----His substitution, are independent of the loss in enzymatic activity. Whereas treatment of purified normal human placental hexosaminidases A and B with arginine-specific modifying reagents produced a time-dependent loss of enzymatic activity toward both alpha-specific and common substrates, these reagents failed to significantly decrease the residual activities of mutant proteins lacking Arg at position 211. Kinetic analysis of the residual enzyme activity from our most conservative construct, Arg211----Lys, determined an apparent Vmax approximately 400-fold reduced from that of the wild type enzyme but detected no change in the apparent Km. Additionally, the pH optimum of this mutant enzyme was narrower and slightly more basic than that of the normal enzyme. Thus, Arg211 in the beta-subunit and, by extrapolation, the Arg178 in the alpha-subunit of beta-hexosaminidase are "active" residues, i.e. part of the catalytic sites, but do not participate in substrate binding.

ACS general surgeons participate in payment reform activities

As reported in the Bulletin at various times over the past several years, the American College of Surgeons has frequently been called upon by federal agencies and commissions to provide clinical information and advice on issues that are associated with implementation of the Medicare physician payment system reforms mandated by the Omnibus Budget Reconciliation Act of 1989 (OBRA '89). In doing so, the College has often relied on the expertise of Fellows who are deeply committed both to the practice of general surgery and to the College. The purpose of this article is to provide a review of the College's participation in activities related to implementation of the Medicare reforms, as viewed by some of the general surgeons who shared in those efforts.