Improvement in pain and bowel function in female irritable bowel patients with alosetron, a 5-HT3 receptor antagonist

BACKGROUND

No currently available treatment provides consistent relief of irritable bowel syndrome. Colonic sensory and motor function are modulated partly through 5HT3-receptors.

AIM

To evaluate effects of the 5HT3-receptor antagonist, alosetron, in irritable bowel syndrome.

METHODS

Randomized, double-blind, placebo-controlled, dose-ranging (1, 2, 4, 8 mg b.d. alosetron), 12-week trial in 370 patients with diarrhoea-predominant or alternating constipation and diarrhoea irritable bowel syndrome. Weekly measurement of adequate relief was the key end-point; other irritable bowel syndrome symptoms were collected daily using an electronic phone system.

RESULTS

Alosetron (1 mg or 2 mg b.d.) significantly (P < 0.05 vs. placebo) increased the proportion of females, but not males, reporting adequate relief. Stool consistency, frequency and percentage days with urgency improved over placebo (P < 0.05) within the first month with all doses of alosetron, and persisted throughout the trial with all doses in female patients. With 1 mg b.d. alosetron, females had improved stool consistency and urgency within the first week, and adequate relief and improved stool frequency within the first 2 weeks. There was no consistent improvement in bowel function among male patients.

CONCLUSION

In female irritable bowel syndrome patients with predominant diarrhoea or alternating constipation and diarrhoea, alosetron is effective in treatment of abdominal pain and discomfort and bowel-related symptoms.

Establishment of the first international standard for nucleic acid amplification technology (NAT) assays for HCV RNA. WHO Collaborative Study Group

BACKGROUND AND OBJECTIVES

The aims of this study were the establishment of a WHO International standard for HCV RNA for nucleic acid amplification technology (NAT) assays and the determination of the HCV RNA content of the candidate standard.

MATERIALS AND METHODS

Twenty-two laboratories evaluated three candidate materials (two lyophilised, AA and BB, which were derived from the same source and one a liquid preparation, CC). All samples were HCV genotype 1 with a concentration of approximately 10(5) genome equivalents/ml. The methods used included the Roche Amplicor assay (version 1), Chiron Quantiplex (bDNA) assay, Organon Teknika NASBA assay, Transcription Mediated assay and various in-house assays, using single or nested primers.

RESULTS

There was reasonable agreement between the overall mean NAT detectable units/ml obtained by the different assays except for some of the in-house assays using single primers which gave substantially lower estimates. These titres were 5.0 log10 for samples AA and BB and 4.6 log10 for sample CC.

CONCLUSIONS

Sample AA was accepted as the candidate standard and assigned a titre of 10(5) international units (IU)/ml. The International Standard consists of a batch of vials each containing 50,000 IU/vial. Preliminary studies indicated that the material is stable at +4 degrees C and +20 degrees C for up to 200 days.

Comparing the biological and cultural inheritance of personality and social attitudes in the Virginia 30,000 study of twins and their relatives

Measures of four dimensions of personality (Psychoticism, Extraversion, Neuroticism, and Lie scores) and six aspects of social attitudes (to sex, taxation, militarism, politics, religion and a general conservatism scale) were obtained by mailed questionnaire from 29,691 US subjects including adult twins (n = 14,761) their parents (n = 2360), their spouses (n = 4391), siblings (n = 3184) and adult children (n = 4800). After correction for the average effects of age, sex and source of sample, familial correlations were computed for 80 distinct biological and social relationships. The data allow for the estimation of the additive and non-additive effects of genes, assortative mating, vertical cultural inheritance and other non-parental effects of the shared environment on differences in personality and social attitudes. The interaction of genetic and environmental effects with sex may also be analyzed. Model-fitting analyses show that personality and social attitude measures differ markedly in major features of family resemblance. Additive and dominant genetic effects contribute to differences in both personality and attitudes, but the effects of the family environment, including vertical cultural transmission from parent to child, are much more marked for social attitudes than for personality. There is substantial assortative mating for social attitudes and almost none for personality. The causes of family resemblance depend significantly on sex for almost every variable studied. These findings clarify and extend the more tentative findings derived from previous twin, family and adoption studies.

Sociodemographic and health status characteristics with prostate cancer screening in a national cohort of middle-aged male veterans

OBJECTIVES

To characterize variables associated with obtaining prostate cancer screening in a nonclinical, nationally distributed, middle-aged male population.

METHODS

Telephone interviews were administered to 2652 individual members of the Vietnam Era Twin Registry in 1992 and 1995. Dependent variables were self-report measures of having had a digital rectal examination (DRE) and/or a prostate-specific antigen (PSA) test in the past 5 years. Independent variables were current measures of age, household income, education, race, insurance, source of care, and lifetime measures of physical condition, psychiatric illness, and alcohol and nicotine dependence.

RESULTS

Thirty-five percent of the sample reported having had a PSA and DRE within the past 5 years. Prevalence of obtaining either a PSA or DRE varied with age, income, education, and race. Subjects with a regular source of care, a regular physician, and health insurance reported higher rates of having had a DRE or PSA and DRE. Persons with a physical or psychiatric illness reported more screening. A multiple regression model revealed that having a regular source of care, having a regular physician, physical illness, psychiatric illness, minority status, higher income, and age predicted having had some form of screening.

CONCLUSIONS

A substantial portion of middle-aged men have had both a PSA and DRE performed at least once in the preceding 5 years. It may be possible to further improve prostate cancer screening participation by directing educational programs at men who are not in contact with the healthcare system. If the PSA and DRE screening guidelines that are finally adopted discourage screening among low-risk men younger than age 50, educational programs that emphasize age screening criteria may be warranted.

Complex genetic and environmental relationships between psychological distress, fatigue and immune functioning: a twin study

BACKGROUND

Although there is considerable support for adverse relationships between states of psychological and somatic distress and immune response, there is little evidence in humans of the relative contribution of genetic and environmental factors.

METHODS

This study utilized a twin methodology to examine the interplay between psychological distress, fatigue and immune function. We recorded a number of measures of distress, including conventional depression and anxiety as well as the somatic symptom of prolonged fatigue, and immune responsiveness (by delayed-type hypersensitivity skin response) in 124 normal adult twin pairs (79 monozygotic, 45 dizygotic).

RESULTS

While there were strong genetic influences on the psychological distress and fatigue factors (only some of which are common to both), familial aggregation of immune responsiveness arose mainly from environmental factors shared by both members of a twin pair. Phenotypic correlations between psychological and immune measures were negligible, but multivariate genetic modelling revealed that these masked larger genetic and environmental correlations of opposite sign. Negative environmental effects of psychological distress and fatigue on immune responsiveness were countered by a positive genetic relationship between psychological distress and immune function.

CONCLUSIONS

Our study suggests that current psychoneuroimmunological hypotheses in humans need to be modified to place increasing importance on the individual's genotype. In this cohort immune responsiveness varied in response to a complex interplay of genetic and environmental factors. Additionally, although psychological distress and fatigue had some shared genetic determinants, independent genetic and environmental risk factors for fatigue were also identified.

Application of distance geometry to 3D visualization of sequence relationships

SUMMARY

We describe the application of distance geometry methods to the three-dimensional visualization of sequence relationships, with examples for mumps virus SH gene cDNA and prion protein sequences. Sequence-sequence distance measures may be obtained from either a multiple sequence alignment or from sets of pairwise alignments.

AVAILABILITY

C/Perl code and HTML/VRML files from http://www.nibsc.ac.uk/dg3dseq/

Ranitidine bismuth citrate plus clarithromycin: a dual therapy regimen for patients with duodenal ulcer

BACKGROUND

The combination of ranitidine bismuth citrate (RBC) and clarithromycin (CLR) was compared with each treatment alone for the eradication of H. pylori and healing of duodenal ulcers in patients infected with H. pylori.

METHODS

This two-phase, randomized, double-blind, placebo-controlled, multicenter study evaluated 203 patients with an active duodenal ulcer treated with either (1) RBC 400 mg BID for 4 weeks plus CLR 500 mg TID for the first 2 weeks; (2) RBC 400 mg BID for 4 weeks plus placebo TID for the first 2 weeks; (3) placebo BID for 4 weeks plus CLR 500 mg TID for the first 2 weeks; or (4) placebo BID for 4 weeks plus placebo TID for the first 2 weeks. Patients with healed ulcers after treatment entered a 24-week observation phase for the assessment of H. pylori and ulcer relapse.

RESULTS

Four-week ulcer healing rates were higher with RBC + CLR (71%) and RBC alone (66%) compared with placebo (15%; p < 0.05) and CLR alone (49%). H. pylori eradication rates were significantly higher with RBC + CLR (86%) compared with RBC alone (0%, p < .001) or CLR alone (24%, p < .001). Ulcer recurrence rates after 6 months were lower in patients eradicated of H. pylori infection (17%) compared with patients who remained infected (43%). All treatments were well tolerated.

CONCLUSIONS

Ranitidine bismuth citrate plus clarithromycin is a simple, convenient, and well-tolerated dual therapy regimen that is effective in eradicating H. pylori and healing duodenal ulcers in patients infected with H. pylori. The eradication of H. pylori in patients with healed ulcers significantly reduces the rate of ulcer relapse.

A comparison of the Eating Disorder Examination and a general psychiatric schedule

OBJECTIVE

The aim of this study is to investigate the adequacy of a general interview schedule for the purpose of assessing bulimia nervosa.

METHOD

In two waves of data collection 18-24 months apart, 250 women were assessed for disordered eating. The first interview was typical of that included in many psychiatric interview schedules and was used to screen women for selection in a subsequent interview. This latter interview, using the Eating Disorder Examination, represents the 'gold standard' for the assessment of disordered eating.

RESULTS

While the psychiatric interview satisfactorily assessed disturbed eating in general, it seemed less capable of accurately assessing cases of bulimia nervosa in particular, the major weakness being the overestimation of binge-eating.

CONCLUSIONS

Structured psychiatric interviews are suitable for screening purposes to identify women with disordered eating, but identification of bulimia nervosa requires further assessment with a suitable instrument.

International collaborative study to evaluate a recombinant L ferritin preparation as an International Standard

A recombinant L ferritin preparation, lyophilized in ampoules and designated 94/572, was evaluated by 18 laboratories in 9 countries for its suitability as an International Standard (IS). The preparation was assayed in a wide range of in-house and commercial immunoassays against the 2nd IS for ferritin (of spleen origin; 80/578). The immunological reactivity of the recombinant material was similar to that of the 2nd IS for ferritin in the majority of assays and demonstrated adequate stability in accelerated degradation studies. On the basis of the results presented here, the WHO Expert Committee on Biological Standardization established 94/572 as the 3rd IS for ferritin, recombinant.

Age changes in the causes of individual differences in conservatism

Age-related changes are analyzed in the correlation of 3416 monozygotic and 3780 dizygotic U.S. twin pairs aged between 9 and 75+ years for conservatism scores derived from a 28-item social attitude inventory. The effects of the shared environment are overwhelming in twins aged 20 years or younger. In older twins, genetic effects appear to play a larger role. A more dynamic conception of the interaction between genes and environment in the development of complex human differences is needed.

First clinical experiences with specific sheep Fab fragments in snake bite. Report of a multicentre study of Vipera berus envenoming

OBJECTIVES

To evaluate the efficacy and safety of specific, ovine Fab fragments in the treatment of envenoming by the common adder, Vipera berus.

DESIGN

Open study with historical controls.

SETTING

Multicentre study involving patients (n = 30) with V. berus envenoming, treated in 18 Swedish hospitals during 1991-94.

MAIN OUTCOME MEASURES

Initial symptoms, clinical course after treatment, duration of hospital stay and adverse effects of the antivenom were evaluated. Two earlier studied patient groups, given either equine F(ab)2 antivenom (n = 30) or no antivenom (n = 16), were used as controls.

RESULTS

Specific ovine Fab fragments influenced favourably the acute symptomatology as well as the long term clinical course. Acute symptoms such as hypotension, shock, vomiting, diarrhoea and CNS-depression resolved quickly. The incidence of extensive swelling involving the trunk and the length of hospital stay were both reduced significantly compared to nontreated patients (23 vs. 88% and 3.5 vs. 6 days). Also the incidence of anaemia was reduced (23 vs. 44%). These results were consistent with those obtained with equine F(ab')2 antivenom, but with ovine Fab there were no immediate anaphylactic reactions or serum sickness.

CONCLUSION

Specific Fab fragments produced from sheep immunized with V. berus venom were safe and effective in counteracting the effects of V. berus bite in humans. These results justify further studies of this new treatment for snake envenoming.

Collaborative study on assays of activated FIX (FIXa). On behalf of the factor VIII and factor IX subcommittee of the ISTH. International Society on Thrombosis and Haemostasis

A collaborative study has been organised by NIBSC to examine the performance of FIXa assays between laboratories, and to investigate the need for a standard. Ampoules of 3 materials, one monocomponent concentrate (coded C) and 2 different preparations of purified human FIXa (one proposed reference preparation, coded A and a test material coded B), have been assayed in 11 laboratories for FIXa using either the NIBSC method or a local method, with local standards (if available, coded D) to determine their potencies. The data showed high between assay variability; with the exception of one laboratory, most of the between assay variation expressed as %geometric coefficients of variation (gcv) were over 15%. The interlaboratory gcv when preparation B was assayed against the local standard was over 1700%, suggesting that most of the local standards are poorly calibrated. The %gcv was improved to 80% when reference A was used as the standard. These data clearly show that an international reference standard for FIXa would help to standardise FIXa preparations and would also improve in house assays for FIXa. However, an accelerated degradation study has shown that reference A is not suitable as a long term standard and another material with suitable stabilizers has to be established as an international standard for FIXa.

Effects of ranitidine bismuth citrate on gastric acid secretion and gastrin release in subjects with and without Helicobacter pylori infection

BACKGROUND

Ranitidine bismuth citrate is a novel antiulcerant that provides the antisecretory activity of ranitidine and the gastric mucosal protection and antibacterial properties of bismuth.

METHODS

This randomized, double-blind, placebo-controlled study evaluated the effects of single doses of ranitidine bismuth citrate 200 mg, 400 mg and 800 mg and ranitidine hydrochloride 150 mg on gastrin release and suppression of gastric acid secretion, and compared acid secretory profiles and gastrin release between Helicobacter pylori-negative and -positive patients. Plasma gastrin concentrations were determined by radioimmunoassay under basal conditions and in response to peptone meal stimulation. Acid secretion was measured under basal conditions and in response to peptone meal stimulation. Presence of H. pylori was determined by both 14C-urea breath test and ELISA serology.

RESULTS

Inhibition of gastric acid output by ranitidine bismuth citrate was both time- and dose-dependent over the 9-h post-dose study period. Doses of ranitidine bismuth citrate 400 mg and ranitidine hydrochloride 150 mg, which are equimolar, produced similar suppression of acid output regardless of H. pylori status. Ranitidine bismuth citrate had no effect on plasma gastrin concentrations regardless of H. pylori status. All doses of ranitidine bismuth citrate were well tolerated.

CONCLUSIONS

Ranitidine bismuth citrate caused time- and dose-dependent reductions in meal-stimulated and between-meal gastric acid output regardless of H. pylori status. The magnitude of decreased acid secretion was similar with ranitidine bismuth citrate 400 mg and ranitidine hydrochloride 150 mg. Ranitidine bismuth citrate had no effect on plasma gastrin concentrations.

Social contact, social attitudes, and twin similarity

The nature of the relationship between social contact and attitude similarly between twins was investigated using longitudinal data from a sample of Australian twins. Earlier research has suggested that social attitudes are not explained solely by shared environment; rather there are both genetic and environmental components that explain variance in social attitudes. Using three types of analyses we investigated the magnitude of the relationship and the direction of causation between attitude similarity and social contact. Longitudinal analysis of within-pair variance by level of contact suggests that attitude similarity leads to contact among the females and that similarity is both genetically and environmentally based. Analyses using a crosslag regression model suggest that similarity causes contact among MZ females. Biometrical analyses indicate differences in direction of causation for males and females. Among females, both genetic and shared environmental parameter estimates could be equated across contact groups, suggesting little relationship between contact and similarity. Among males, findings of smaller estimated heritability in the high-contact group suggest that similarity causes contact. However, an increased estimate of the contribution of shared environmental variance in the high-contact males could additionally suggest that contact leads to similarity.

Similar patterns of simian immunodeficiency virus env sequences are found in the blood and lymphoid tissues of chronically infected macaques

Two cynomolgus macaques were infected with a genetically complex challenge stock of simian immunodeficiency virus (SIVmac251-32H). One animal developed SIV-induced disease and was sacrificed at 16 months postinfection. The second remained healthy until it too was sacrificed at 20 months postinfection. The polymerase chain reaction (PCR) was used to amplify env gp120-coding sequences from provirus present in samples of blood, spleen, and inguinal lymph node taken from both animals on the day of sacrifice. The proviral burden present in each of the tissue samples was also determined using a quantitative PCR assay. The proviral burdens in the blood, spleen, and inguinal lymph node of the healthy animal (I225) were similar. This was not the case for animal I227, in which the burden in the inguinal lymph node was much higher than for blood or spleen. Phenogram analysis of the hypervariable V1 region of env revealed that the diversity of nucleotide sequences recovered from each tissue of both macaques were similar and overlapping. Some selected amino acid differences were observed that were specific for a tissue or one of the macaques. However, the results do not suggest that the overall evolution of env in provirus populations recovered from lymphoid tissues is distinct from that recovered from the blood.

GIP and GLP-1(7-36)amide secretion in response to intraduodenal infusions of nutrients in pigs

Investigation of nutrient stimulation of two gut hormones GIP (glucose dependent insulotropic polypeptide) and GLP-1(7-36)amide (the active truncated form of glucagon-like peptide-1) is made difficult by the differential control of gastric emptying. Direct nutrient infusion into the duodenum was therefore carried out on three female pigs. The infusates consisted of saline (0.85 g or 1.7 g/100 ml); glucose (20 g or 40 g/100 ml); fat (30 g or 60 g/500 ml) and glucose/fat (20 g and 30 g or 40 g and 60 g per 1000 ml). Plasma glucose levels were elevated as expected by glucose or glucose/fat infusions, and they were not affected by the presence of fat in the infusate. Insulin secretion was stimulated in the presence of glucose or glucose/fat. Plasma triacylglycerol was elevated following fat and glucose/fat infusions. The greatest stimulus for GIP secretion was glucose/fat (P < 0.05); fat alone was a poor stimulus for GIP secretion, but glucose was a potent stimulus. GLP-1(7-36)amide was moderately stimulated by glucose and markedly stimulated by fat and glucose/fat infusions (P < 0.05). We conclude that, in pigs, dual nutrient infusion of glucose/fat is a strong stimulus for both GIP and GLP-1(7-36)amide secretion. The hormones therefore have the potential to play an important physiological role, both in the stimulation of insulin secretion and in adipose tissue metabolism in pigs.

Creating care partnerships with long-distance caregivers

Primary family caregivers cannot always physically be there to care for aging relatives; they may live in another state or even another country. By developing a care partnership, however, with a provider and the older relative, long-distance caregivers can be assured that relatives get the care they need from qualified and effective providers.

Primary plasma antioxidants in adult respiratory distress syndrome patients: changes in iron-oxidizing, iron-binding, and free radical-scavenging proteins

Ten adult patients (three male, age range, 15 to 67 years) with established ARDS were studied for serial changes in the proteinaceous antioxidant activities of their plasma. All had LISs in excess of 2.5 on admission to the study. Blood samples were taken as soon as possible after the diagnosis of ARDS, and from 10 patients at risk of developing ARDS. These were compared with healthy control subjects. Deoxyribose, phospholipids, and DNA were used as markers of damage in reactions generating inorganic and organic oxygen radicals and an oxo-iron species. The ability of plasma to inhibit such damage was expressed as antioxidant activity. This study does not address the clinical problem of why certain "at risk" patients develop ARDS, but rather the question of why some patients with established ARDS are better able than others to survive the disease. ARDS patients had transferrin levels that were significantly lower (1.76 +/- 0.13 gm/L) than those of normal controls (2.91 +/- 0.12 gm/L, p < 0.001), which decreased the ability of their plasma to protect phospholipid membranes and DNA against iron-stimulated free radical damage. The iron-oxidizing antioxidant properties of plasma were mainly dependent on the protein ceruloplasmin, concentrations of which were significantly higher in ARDS patients (0.387 +/- 0.04 gm/L) than in healthy controls (0.265 +/- 0.03 gm/L, p = < 0.05) or patients at risk of ARDS (0.24 +/- 0.04 gm/L, p = < 0.05). The iron-oxidizing (ferroxidase) antioxidant activities of plasma from ARDS patients, however, were similar to those of both control groups. Measurement of plasma ferroxidase activities confirmed that although more ceruloplasmin was present in the plasma of ARDS patients, enzyme activities were comparable to those of both control groups, which was suggestive of a loss of ceruloplasmin ferroxidase activity. Scavenging and radical-stimulating properties of plasma (devoid of iron-binding and iron-oxidizing properties) was partly dependent on protein thiol groups, which were lower in ARDS patients and in patients at risk of developing ARDS. Serial sample analysis revealed that ARDS patients showed substantial daily variations in biochemical parameters, implying that single time-point sampling may be unsuitable when studying these patients.

Perceived support and adjustment to stress in a general population sample of female twins

The stress-buffering effect of perceived support is explored in a large panel survey of adult female twins. The analysis begins by documenting a significant interaction between perceived support and acute stress in predicting DSM-III-R major depression. Various hypotheses are investigated to explain this interaction. These include the possibilities that the interaction is due to a stress-buffering effect of perceived support which is mediated by received support, that perceived support promotes either the increased use or the increased effectiveness of certain coping strategies, or that there is some underlying genetic factor that affects both the perception of support and adjustment to stress. No evidence was found for any of these hypotheses. The paper closes with a discussion of directions for future research aimed at explaining the interaction between perceived support and acute stress.

A twin study of recent life events and difficulties

OBJECTIVES

To examine the role of genetic and familial-environmental factors in the origin of stressful life events.

DESIGN

Self-report questionnaires describing stressful life events in the last year.

PARTICIPANTS

Both members of 2315 twin paris ascertained from the population-based Virginia Twin Registry.

RESULTS

Life events were modestly but significantly correlated in twin pairs, and correlations in monozygotic (MZ) twins consistently exceeded those in dizygotic (DZ) twins. For total life events, the best-fitting twin model indicated that familial-environmental and genetic factors each accounted for around 20% of the total variance. Individual life events could be best divided into "network events" (directly affecting individuals in the respondent's social-network) where twin resemblance was due solely to the familial environment, and "personal" events (directly affecting the response) where most twin resemblance was the result of genetic factors.

CONCLUSIONS

While neither genes nor familial environment is likely to directly produce life events, personal and social factors that predispose to life events are substantially influenced by an individual's genetic and family background. These results, which suggest that stressful life events reflect more than random influences, may have important implications for our understanding of the relationship between stressful life events and psychopathology.

Restriction of serum antibody reactivity to the V3 neutralizing domain of HIV gp120 with progression to AIDS

OBJECTIVE

To identify epitopes on HIV-1 gp120 that correlate with disease resistance and/or prognostic indication.

DESIGN

The identification of epitopes on HIV-1 gp120 was determined by testing the reactivity by immunoblotting of anti-HIV-positive human sera against partially cleaved Chinese hamster ovary (CHO) cell-derived recombinant gp120. Cleavage of recombinant gp120 occurs in the V3 loop region resulting in 70 and 50K cleavage bands if the protein is subjected to sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) under reducing conditions. Antibodies reactive with the 120 Mr band alone on immunoblotting indicate that binding is restricted to this cleavage site. Reactivity to either of the cleavage products is independent of gp120 cleavage and indicates that binding occurs in sites other than the V3 cleavage region.

METHODS

A panel of anti-HIV-positive human sera was tested for virus neutralizing activity and reactivity by immunoblotting against CHO cell-derived gp120.

RESULTS

All sera reacted with the uncleaved from of gp120 but reacted either weakly or did not react with its cleavage products. There was a statistically significant correlation between serum reactivity to cleavage products and clinical stage of disease [Centers for Disease Control (CDC) criteria]. Sera of asymptomatic individuals (CDC stage II/III) were more likely to recognize either one or both of the cleavage products compared with sera from patients presenting with symptoms of disease (CDC stage IV). Furthermore, sera reacting with either one or both of the cleavage products were more likely to have higher neutralizing antibody titres than those that were unreactive.

CONCLUSIONS

There is a restriction of serum antibody reactivity (when tested by immunoblotting) to the V3 loop with progression to disease. Raised neutralizing antibody titres may be dependent on regions outside the V3 cleavage site.

Social support, depressed mood, and adjustment to stress: a genetic epidemiologic investigation

A survey of 821 same-sex female twin pairs from a population-based registry assessed 8 dimensions of social support and social integration. Twin analyses documented significant common environmental influences on 5 of these 8 measures and significant genetic influences on 5 of the 8. A decomposition of the multiplicative association between support and a measure of stressful life experiences in predicting depressed mood--an association typically interpreted as providing evidence for a stress-buffering effect of social support--shows clearly that it is the environmental and genetic factors that cause support, rather than support itself, that buffer the effects of stress on mood in most cases. We discuss the implications of this result for future research on the relationship between social support and psychopathology.

Population sequence analysis of a simian immunodeficiency virus (32H reisolate of SIVmac251): a virus stock used for international vaccine studies

The virus structural genes gag and env (both gp120 and gp41 regions) of the 32H isolate of SIVmac251 were amplified using the polymerase chain reaction (PCR). The proviral template used in the PCR was DNA isolated from cells used to prepare several experimental SIV vaccines, which have been tested in simians, and a standard challenge stock of virus, which has been used in international collaborative studies. The PCR products were cloned and the nucleotide sequences of several clones were determined for each gene. From a comparison of the sequences obtained the predominant amino acid sequences of gag and env were predicted and the degree of sequence heterogeneity was determined. Conserved and more variable regions of each protein were identified. The gp120 region of env was more heterogeneous than gag or the transmembrane protein of env (gp41). Within gp120, sequence variability was concentrated to specific regions equivalent to the V1, V2, and, to a lesser extent, the C1 regions identified for human immunodeficiency virus type 1 (HIV-1). In contrast the region equivalent to the hypervariable "V3-loop" of HIV-1 was highly conserved. The implications of the data is discussed in relation to the ability of this virus stock to prepare effective vaccines against SIV.

Severe amitriptyline overdose: relationship between toxicokinetics and toxicodynamics

The clinical features and toxicokinetics of amitriptyline were studied in nine patients with severe amitriptyline poisoning. Amitriptyline and amitriptyline metabolites were studied in plasma, red blood cells, and cerebral spinal fluid. Eight patients were intubated and six required assisted ventilation. Two patients had ventricular arrhythmias, three patients convulsions and two were hypotensive. All complications developed within four hours of admission. Early in the course of the intoxication the QRS duration correlated with plasma, unbound and red blood cell nortriptyline concentration. The QRS duration also correlated with unbound but not the plasma amitriptyline concentration. The level of consciousness correlated with the plasma and unbound amitriptyline both in alpha and beta phase and with red blood cell amitriptyline in alpha phase. There was no correlation between nortriptyline concentration and level of consciousness. No correlation between coma grade or QRS duration and cerebral spinal fluid concentration of amitriptyline was found. There was no correlation between any hydroxymetabolite in blood or cerebral spinal fluid and QRS duration or coma grade. The beta half-life for amitriptyline was shorter for two patients with high concentrations of hydroxymetabolites. Although intubated, neither patient required assisted ventilation or developed complications. Because of the wide range of concentrations of amitriptyline and amitriptyline metabolites observed between individuals, it is not possible to predict outcome based on a single tricyclic antidepressant concentration.

Amitriptyline and amitriptyline metabolites in blood and cerebrospinal fluid following human overdose

The toxicokinetics of amitriptyline were studied in nine patients admitted to hospital in Matthew-Lawson Coma Scale grade III-IV after an estimated ingestion of 1-5 g amitriptyline. Gastric lavage was performed and 50 g activated charcoal were given orally. Venous blood samples were taken on admission and at 1, 2, 4, 8, and 24 h, and in some patients at 36 and 48 h after admission. Arterial blood samples were taken at 1, 4, 8, and 24 h after admission. Lumbar punctures were performed 1 h after admission in 8 patients and again 4 h later in 5 patients. A urine sample was screened for other drugs. The bound and unbound fraction of amitriptyline and its metabolites nortriptyline, E and Z forms of 10-OH-amitriptyline and nortriptyline were analyzed in plasma, whole blood, red blood cells, and cerebrospinal fluid using an HPLC technique. The T1/2 alpha and T1/2 beta for amitriptyline were 1.5 - 3.1 and 15 - 43 h respectively. The rate of elimination of amitriptyline was not dose-dependent. The arteriovenous differences in the total amitriptyline+nortriptyline concentration were maximal in patients admitted soon after intake of drugs. Amitriptyline concentrations in cerebrospinal fluid were quantitatively similar to the unbound amitriptyline concentration in blood. The highest cerebrospinal fluid amitriptyline concentration was 506 nmol/L. There were large individual differences in plasma, blood and cerebrospinal fluid concentrations between different individuals. Repeated quantitative analysis of amitriptyline and its metabolites is unlikely to contribute to the clinical management of most patients with amitriptyline overdose.

Predicting severity of tricyclic antidepressant overdose

The measurement of plasma concentration, a prolonged QRS interval, and level of consciousness have all been recommended as useful indicators of toxicity following tricyclic antidepressant overdose. The aims of this study were firstly, to determine the relative prognostic value of each of these indicators and secondly, to assess when a patient can be discharged safely from the intensive care unit. Data were evaluated on 67 patients with tricyclic antidepressant overdose from four centers. Plasma tricyclic antidepressant concentrations were measured, coma grade was evaluated using the Matthew-Lawson Coma Scale and a ECG was obtained from 23 patients on admission. Complications such as convulsions, hypotension, arrhythmias, and need for intubation and ventilation were recorded. Thirty patients developed complications and no patient died. Coma grade was the best predictor of outcome. The development of serious complications is unlikely in patients whose level of consciousness is grade II or less and who are admitted to hospital more than 6 h after overdose. Plasma tricyclic antidepressant concentration was of no additional value in predicting toxic complications or deciding when the patient could leave the intensive care unit. Our study suggests that an alert and orientated patient with a QRS duration less than 100 ms is the best indicator for safe transfer to a medical or psychiatric ward.

Social support, depressed mood, and adjustment to stress: A genetic epidemiologic investigation

A survey of 821 same-sex female twin pairs from a population-based registry assessed 8 dimensions of social support and social integration. Twin analyses documented significant common environmental influences on 5 of these 8 measures and significant genetic influences on 5 of the 8. A decomposition of the multiplicative association between support and a measure of stressful life experiences in predicting depressed mood--an association typically interpreted as providing evidence for a stress-buffering effect of social support--shows clearly that it is the environmental and genetic factors that cause support, rather than support itself, that buffer the effects of stress on mood in most cases. We discuss the implications of this result for future research on the relationship between social support and psychopathology.

The genetic epidemiology of bulimia nervosa

OBJECTIVE

The authors seek to clarify, from both an epidemiologic and genetic perspective, the major risk factors for bulimia nervosa and to understand the relationship between narrowly defined bulimia and bulimia-like syndromes.

METHOD

Personal structured psychiatric interviews were conducted with 2,163 female twins from a population-based register. Psychiatric disorders were assessed using DSM-III-R criteria.

RESULTS

Lifetime prevalence and risk for narrowly defined bulimia were 2.8% and 4.2%, respectively. Including bulimia-like syndromes increased these estimates to 5.7% and 8.0%, respectively. Risk factors for bulimia included 1) birth after 1960, 2) low paternal care, 3) a history of wide weight fluctuation, dieting, or frequent exercise, 4) a slim ideal body image, 5) low self-esteem, 6) an external locus of control, and 7) high levels of neuroticism. Significant comorbidity was found between bulimia and anorexia nervosa, alcoholism, panic disorder, generalized anxiety disorder, phobia, and major depression. Proband-wise concordance for narrowly defined bulimia was 22.9% in monozygotic and 8.7% in dizygotic twins. The best-fitting model indicated that familial aggregation was due solely to genetic factors with a heritability of liability of 55%. A multiple threshold model indicated that narrowly defined bulimia nervosa and bulimia-like syndromes represented different levels of severity on the same continuum of liability.

CONCLUSIONS

The liability to fully syndromal bulimia nervosa, which affects around one in 25 women at some point in their lives, is substantially influenced by both epidemiologic and genetic risk factors. The same factors that influence the risk for narrowly defined bulimia also influence the risk for less severe bulimia-like syndromes.

Chronic neuropsychological and neurological impairment following acute exposure to a solvent mixture of toluene and methyl ethyl ketone (MEK)

A 38 year-old laborer experienced solvent intoxication during each of two spray paintings of a dump truck and other heavy equipment in an enclosed, unventilated garage. The paint base consisted primarily of toluene and methyl ethyl ketone. Nausea, headaches, dizziness, respiratory difficulty and other symptoms began after exposures. Over the next several days he developed impaired concentration, memory loss and cerebellar signs including an intention tremor, gait ataxia and dysarthria. MRI of the brain and EGG early in the work-up were normal, although later MRIs demonstrated fluid collection over the left parietal area. Examination by a toxicologist and neurologist revealed likely toxic encephalopathy with dementia and cerebellar ataxia. Three formal neuropsychological assessments over 2 1/2 years quantified cognitive, motor and behavioral changes. Despite similar findings in chronic exposure to these solvents, lasting sequelae following acute exposure have not been widely reported.

Report of a collaborative study for assessing the potency of hepatitis B vaccines

A collaborative study was carried out to examine the suitability of a hepatitis B vaccine derived from plasma as an immunogenicity reference for vaccines produced by recombinant DNA technology in yeast. The use of a plasma derived vaccine as reference appeared satisfactory, although the use of homologous reference improved agreement in potency estimates. The use of a recombinant standard did not however improve agreement for a recombinant vaccine produced by a different manufacturer. The variation in the dilution of vaccine required to induce antibodies in 50% of test animals and in potency estimates varied widely between laboratories (25-fold and 10-fold respectively). However this was similar to the variation found in a previous collaborative study.

Severity grading in self-poisoning

1. The reliability and validity of three different coma scales was studied in 26 patients with acute drug overdose. 2. A comparison of six painful stimulation techniques showed that sternal rubbing and retromandibular pressure were most effective. 3. The improper use of stimulation techniques may underestimate level of responsiveness in 4-19% of cases. 4. The Reaction Level Scale (RLS) was the most reliable scale. 5. Both the RLS and the Glasgow Coma Scale may be unnecessarily complicated for the evaluation of the drug overdose patient, but should be chosen if concomitant brain injury is suspected. 6. This study confirms the basic concepts and shows the reliability of the Matthew-Lawson scale for use in the poisoned patient.

Effects of naloxone and verapamil in experimental amitriptyline poisoning in rats

The effects of verapamil and naloxone as potential antidotes for amitriptyline-induced cardiotoxicity were investigated in an experimental rat model. Amitriptyline was infused continuously at a dose of 37.5 mg/kg/h. After 15 minutes, the animals were given either naloxone (2 mg/kg + 3 mg/kg/h), verapamil (0.08 mg/kg + 0.08 mg/kg/h), or physiological saline. In the group given naloxone, a significant decrease in heart rate was seen. Although MAP and max dP/dT increased, there was no significant difference from controls. Naloxone did not decrease mortality. When the bolus dose of verapamil was given, a significant decrease in MAP and max dP/dT was obtained. Although the mean blood pressure was significantly higher in those animals treated with verapamil who survived 60 minutes, verapamil did not change the course of the amitriptyline poisoning. In conclusion, our findings indicate that naloxone lacks significant positive effects and that verapamil has an additional negative inotropic effect. Neither drug can be recommended for the treatment of amitriptyline poisoning.

Clinical and metabolic features of ethanol-methanol poisoning in chronic alcoholics

The kinetics of methanol were examined in 84 chronic alcoholics admitted after drinking a cleansing solution containing 90% ethanol and 5% methanol. On admission, the average blood methanol concentration was 20 mmol/l (64 mg/dl) and blood ethanol concentration was 39 mmol/l (179 mg/dl). Although these patients were not treated with ethanol, and methanol concentrations remained high as blood ethanol concentrations fell to zero, no acidosis or other signs of classic methanol poisoning developed. The rate of metabolism of methanol was correlated to the initial ethanol concentration. To avoid unnecessary invasive therapy, treatment of methanol poisoning should be based on the case history, clinical signs, and laboratory features-not solely on blood methanol concentrations.

Clonidine interaction in amitriptyline poisoning

The effect of clonidine on amitriptyline-induced cardiotoxicity was investigated in an experimental rat mode. A continuous infusion of amitriptyline (30 mg/kg/h) was given until the animal died, usually within 2 hours. Fifteen minutes after starting the amitriptyline infusion, 50 micrograms/kg of clonidine was given intravenously over five minutes. This led to an increase in blood pressure and left ventricular end-diastolic pressure. There was no significant change in cardiac contractility. Heart rate decreased. These changes can be explained by an increase in afterload due to peripheral vasoconstriction. No signs of reduced sympathetic outflow were seen on the ECG. The peripheral effects of clonidine dominated over the central effects, which may be due to a competitive inhibition of amitriptyline at central noradrenergic sites. An increased afterload pushes the heart towards failure and increases mortality. In this model, clonidine did not reverse amitriptyline-induced cardiovascular toxicity. It may even be potentially harmful if used to treat tricyclic antidepressant poisoning.

Terbutaline concentrations in self-poisoning: a case report

A young female patient was admitted twice within two months, each time after an overdose of 500 mg terbutaline. Clinical features included nausea, tachycardia, tremor, hyperglycemia and hypokalemia. Although plasma concentrations of terbutaline were at least 50 times the normal therapeutic level, after potassium substitution the outcome was uneventful.

Role of extracorporeal drug removal in acute theophylline poisoning. A review

Theophylline, with its narrow therapeutic margin, is a common cause of iatrogenic and deliberate overdose. Most cases of self-poisoning are with sustained release preparations, with peak concentrations occurring up to 12 or more hours after overdose. Toxic symptoms are often seen at concentrations above 15 mg/L. Theophylline is metabolised within the cytochrome P-450 system, with an average total body clearance of 50 to 60 ml/min. Clearance is, however, affected by many factors such as other drugs or disease, and in overdose zero order kinetics may result in prolonged half-lives. Toxicity is characterised by agitation, tremor, nausea, vomiting, abdominal pains, seizures, and tachyarrhythmias. Hypokalaemia and metabolic acidosis are more profound in acute toxicity, and hypercalcaemia is usually present. Seizures occur at lower concentrations after chronic over-medication than after acute overdose. Gastric lavage should be performed in all patients presenting early, and an oral multiple dose charcoal regimen started with 50 to 100g charcoal, repeating with 50g doses and checking theophylline concentrations at 2- to 4-hour intervals. Multiple dose charcoal can be expected to double the clearance of theophylline, being as effective as a haemodialysis. Of the invasive techniques available, charcoal haemoperfusion is the most effective, increasing clearance 4- to 6-fold. Supportive care is particularly important. The aggressive supplementation of potassium, treatment of emesis with droperidol and ranitidine, and treatment of tachyarrhythmias and hypotension (possibly with propranolol), together with oral multiple dose charcoal may obviate the need for haemoperfusion. Seizures suggest increased morbidity and mortality. Charcoal haemoperfusion should be considered if plasma concentrations are greater than 100 mg/L in an acute intoxication or greater than 60 mg/L in a chronic intoxication. The decision to haemoperfuse should not be based on plasma concentrations alone, but an overall evaluation of the patient's laboratory and clinical status.

Does alcohol absorb to activated charcoal?

Activated charcoal seldom is used in pure-alcohol poisoning since it is absorbed rapidly from the gut. Furthermore in early reports activated charcoal was found to adsorb alcohol poorly. However, in 1981 North et al. [North, D. S., Thompson, J. D. & Peterson, C. D. (1981). Am. J. Hosp. Pharm., 38, 864-866] demonstrated in dogs that charcoal given at the same time as alcohol can reduce the blood alcohol concentration significantly. To study whether charcoal is of value in a clinical situation, a randomized cross-over study in two phases was conducted. Each person drank 88 g of alcohol and 30 min after either 20 g of activated charcoal was taken or the same volume of water was drunk. There were no significant differences in plasma alcohol concentrations with or without charcoal.

Symptoms of anxiety and depression in a volunteer twin population. The etiologic role of genetic and environmental factors

We examined the etiologic role of genetic and environmental factors in 14 symptoms of anxiety and depression reported by 3,798 pairs of adult twins from the Australian National Health and Medical Research Council Twin Register. Multifactorial multiple-threshold models fit the individual symptom scores well. For a substantial majority of the symptoms, the variance in liability was best explained by only genetic factors and environmental influences specific to the individual, where 33% to 46% of the variance was due to genetic factors. For four symptoms, it was not possible to choose definitively between models that, in addition to specific environment, included genetic vs familial environmental effects. These results provide strong evidence for the role of genetic factors in the etiology of symptoms of anxiety and depression as reported in a general population. Evidence for an etiologic role of familial environmental factors was much weaker. If familial environmental factors play any role in the production of these symptoms, they are more important in symptoms of depression than of anxiety, and the factors that predispose to these symptoms are only modestly correlated in males and females.

Haemoperfusion: a useful therapy for a severely poisoned patient?

Although it is many years since a haemodialysis and haemoperfusion over uncoated and later coated charcoal columns have been used for the treatment of intoxicated patients, the clinical efficacy of these extracorporeal techniques in the treatment of severely poisoned patients remains a matter of debate. Some of the reasons for this controversy may be the indiscriminate use of haemoperfusion in any form of intoxication, the lack of well-controlled studies and the wrong interpretation of the high haemoperfusion clearance values sometimes obtained. Simple pharmacokinetic principles are applied to this type of treatment and some practical guidelines as to how and when haemoperfusion should be applied or presented are reviewed. The limited place of haemoperfusion in the treatment of severe poisoning, its further declining use in the future, at least in its present design, and some promising new treatments are emphasized.