Identification of human herpesvirus 8-specific cytotoxic T-cell responses

Human herpesvirus 8 (HHV-8) (or Kaposi's sarcoma-associated herpesvirus) is implicated in the etiopathogenesis of Kaposi's sarcoma (KS) and certain lymphoproliferations. The introduction of more effective therapies to treat human immunodeficiency virus infection has led to a decline in the incidence of KS and also in the resolution of KS in those already affected. This suggests that cellular immune responses including cytotoxic T lymphocytes (CTLs) could play a vital role in the control of HHV-8 infection and in KS pathogenesis. Here we elucidate HLA class I-restricted, HHV-8-specific cellular immune responses that could be important in the control of HHV-8 infection and subsequent tumor development. We show the presence of CTLs against HHV-8 latent (K12), lytic (K8.1), and highly variable (K1) proteins in infected individuals.

Hepatotoxicity possibly caused by amphotericin B

OBJECTIVE

To report a case of possible amphotericin B-induced hepatotoxicity in a patient with pulmonary blastomycosis.

SUMMARY

A 26-year-old white man with life-threatening pulmonary blastomycosis developed elevation of his liver enzymes after the addition of amphotericin B to his initial itraconazole therapy. The hepatotoxicity resolved rapidly with discontinuation of the amphotericin B, and the blastomycosis was successfully treated with itraconazole alone.

DISCUSSION

This case illustrates an unusual occurrence of hepatotoxicity associated with a short course of amphotericin B. Liver biopsy was compatible with drug-induced changes and showed no evidence of blastomycosis. Discontinuation of amphotericin B with no other therapeutic changes resulted in a rapid resolution of hepatotoxicity. A possible adverse drug interaction with itraconazole and amphotericin B is postulated based on the mechanism of action of each drug.

CONCLUSIONS

Amphotericin B therapy can be associated with many adverse effects, but reports of hepatotoxicity are rare. Closer monitoring of liver enzymes in patients receiving amphotericin B, especially in combination with potentially hepatotoxic agents, including azole antifungal drugs, would be prudent.

Alterations in atrial electrophysiology associated with chronic atrial fibrillation in man

BACKGROUND

The purpose of this study was to determine the changes in atrial electrophysiology associated with chronic persistent atrial fibrillation in man.

METHODS AND RESULTS

Atrial monophasic action potential duration at 90% repolarization and the effective refractory period were measured in 13 patients with chronic persistent atrial fibrillation after low-energy endocardial cardioversion, and compared to eight controls without a history of atrial fibrillation. Measurements were made at the right atrial appendage and midlateral right atrial wall at basic, 600 ms and 400 ms drive cycle lengths. In control patients, the effective refractory periods were significantly longer at the atrial appendage than the lateral wall at 600 ms (right atrial appendage 265 ms, midlateral right atrial wall 228 ms, P<0.05), and 400 ms cycle lengths (right atrial appendage 270 ms, midlateral right atrial wall 218 ms, P<0.05), but this was not evident in patients with atrial fibrillation. The monophasic action potentials and effective refractory periods at both atrial sites were shorter in the atrial fibrillation patients compared to controls; however, only the effective refractory periods at atrial appendage at 600 ms (atrial fibrillation 210 ms, controls 265 ms, P<0.001), and 400 ms cycle lengths (atrial fibrillation 200 ms, controls 270 ms, P>0.001) reached statistical significance. Effective refractory period dispersion was significantly greater in controls than in patients with atrial fibrillation (cycle length 600 ms: controls 36, atrial fibrillation 13, P=0.01; cycle length 400 ms: controls 54, atrial fibrillation 18, P<0.01).

CONCLUSIONS

In patients without a history of atrial fibrillation, the refractory period at the right atrial appendage is significantly longer than at the midlateral right atrial wall. This 'normal' pattern of atrial refractory dispersion is lost in patients with chronic persistent atrial fibrillation, with marked shortening of the effective refractory period at the right atrial appendage. This may explain the high risk of recurrence of atrial fibrillation following successful electrical cardioversion.

The extended transbasal approach: a quantitative anatomical and histological study

Since its introduction in 1972 the transbasal approach to the anterior fossa and sphenoethmoidal region has undergone a number of modifications. The extended transbasal approach with preservation of olfaction not only improves exposure of the anterior fossa, but also provides access to the clivus as far inferiorly as the foramen magnum. An anatomical study has been undertaken to photographically demonstrate and quantify the varying degrees of exposure that this technique provides. The pituitary stalk was used as an intracranial target. The amount of exposure was compared using a standard subfrontal approach, a transbasal approach and an extended transbasal with preservation of olfaction. In addition, a histological study was carried out to investigate the level to which identifiable olfactory nerves extended into the nasal mucosa. The anatomical study demonstrates the area of the "external window of exposure" can be doubled using a transbasal approach and more than quadrupled using the extended transbasal approach, when gaining access to the pituitary stalk. In addition, the study highlights the exposure of other anatomical areas, such as the medial orbit, the cavernous sinus, the clivus and the vertebrobasilar complex. The histological study establishes that the olfactory nerves extend only 10 mms below the cribriform plate.

Pharmacology of anthelmintic resistance

Anthelmintic resistance has grown from a curiosity to an important economic problem in several animal industries and is now set to threaten the control of human parasites. The pharmacology of anthelmintics and anthelmintic resistance has been studied most extensively in the nematode parasites of sheep. Here, Nick Sangster and Jenny Gill discuss this veterinary experience, summarizing the progress made in understanding anthelmintic resistance and highlighting the tools available for research.

In vitro human Th-cell responses to a recombinant hepatitis C virus antigen: failure in IL-2 production despite proliferation

Hepatitis C Virus (HCV) causes chronic infection in 80-90% of those exposed and persists despite evidence of immune recognition. To understand the immunological basis of this phenomenon, we have synthesized a non structural (NS) protein that is critical to HCV infection and replication, NS3, and used it to study in vitro helper T-cell responses from infected individuals. Strong proliferative responses were generated by peripheral T-cells isolated from a subset of chronically infected patients, but not by normal, non-infected controls. Interestingly, though gamma-interferon (gammaIfn) and IL-10 were both secreted in response to stimulation by NS3 antigen, IL-2 was not. In contrast, IL-2 was secreted in response to influenza virus vaccine antigen. Lack of IL-2 induction was confirmed by a failure to amplify IL-2 mRNA upon NS3 antigen stimulation, whereas IL-4, IL-15, and gammaIfn mRNA were seen as early as 24 h. The predominance of IL-4 and IL-10 and the lack of IL-2 suggests that in vitro responses to at least some HCV antigens are biased towards a Th2 phenotype, which may be conducive to viral persistence.

Functionally distinct T-cell epitopes within the hepatitis C virus non-structural 3 protein

Clearance of Hepatitis C Virus (HCV) infection is an uncommon phenomenon. To understand the mechanism of viral persistence despite active cellular and humoral responses, we examined the in vitro cytokine response of PBMC from an HCV sero-positive, asymptomatic individual to recombinant intact antigen and sixty-nine overlapping peptides of the HCV non-structural (NS) 3 protein. Whereas, intact antigen induced strong proliferation and significant levels of gammaIFN and IL-10, little or no IL-2 was produced. Only 7% of peptides induced IL-2, which also coincided with their ability to stimulate proliferation. In contrast, 38% of the peptides induced gammaIFN while 35% induced IL-10. All IL-2 stimulating peptides also induced significant levels of gammaIFN and among these, a peptide corresponding to residues 358-375 was the strongest. In addition, 16% of the peptides induced both gammaIFN and IL-10. Exogenous recombinant IL-10 inhibited proliferation and IL-2 induction in response to peptide 358-375. Furthermore, neutralization of IL-10 with an anti-IL-10 antibody resulted in enhanced IL-2 production in response to recombinant NS3 protein. We suggest that IL-10 inducing epitopes within HCV NS3 may thus down-regulate IL-2 dependent T-cell responses.

Cost-effectiveness analysis of a home-based social work intervention for children and adolescents who have deliberately poisoned themselves. Results of a randomised controlled trial

BACKGROUND

Little evidence exists regarding the effectiveness or cost-effectiveness of alternative treatment services in the field of child and adolescent psychiatry.

AIMS

To assess the cost-effectiveness of a home-based social work intervention for young people who have deliberately poisoned themselves.

METHOD

Children aged < or = 16 years, referred to child mental health teams with a diagnosis of deliberate self-poisoning were randomly allocated to either routine care (n = 77) or routine care plus the social work intervention (n = 85). Clinical and resource-use data were assessed over six months from the date of trial entry.

RESULTS

No significant differences were found between the two groups in terms of the main outcome measures or costs. In a sub-group of children without major depression, suicidal ideation was significantly lower in the intervention group at the six-month follow-up (P = 0.01), with no significant differences in cost.

CONCLUSIONS

A family-based social work intervention for children and adolescents who have deliberately poisoned themselves is as cost-effective as routine care alone.

Improving the uptake of selective neonatal BCG immunisation

A survey of selective neonatal BCG immunisation in Bolton in 1993 showed that only 6% of babies in the defined risk groups received BCG. Community medical officers at that time were responsible for administering the BCG. Midwives were trained to take on this role. In 1994, 88% of babies in the defined groups were immunised. This figure has remained stable in subsequent surveys and we are now aiming for 95% uptake.

Detection of thyroglobulin, thyroid peroxidase, and RET/PTC1 mRNA transcripts in the peripheral blood of patients with thyroid disease

PURPOSE

Detection of mRNA transcripts for thyroglobulin (TG), thyroid peroxidase (TPO) and RET/PTC1 in the peripheral blood of patients with thyroid disease.

PATIENTS AND METHODS

TG, TPO, and RET/PTC1 mRNA were analyzed in 52 peripheral-blood samples from 44 patients diagnosed with thyroid carcinoma (24 patients), adenoma (five patients), and nodular hyperplasia (15 patients) by reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

TG and TPO were identified in 13 patients (54.2%) with thyroid carcinoma, which includes five of eight patients with no clinical evidence of disease at the time of blood collection. Four of 5 patients had cervical lymph node metastases and/or extrathyroid extension at the time of the initial surgery. RET/PTC1 mRNA was detected in the peripheral blood of only one patient with papillary thyroid carcinoma. This sample was also positive for TG and TPO. TG and TPO were detected in two patients (10%) with benign thyroid nodules. All positive samples from patients with benign thyroid lesions were collected before surgery, whereas all samples collected after surgery were negative. RET/PTC1 mRNA was not detected in any of the patients with benign thyroid nodules. RT-PCR positivity for TG and TPO mRNA was higher in patients with carcinoma than in patients with benign lesions (P = .002).

CONCLUSION

TG, TPO, and RET/PTC1 mRNA are detectable in the peripheral blood of patients with thyroid disease, which correlates with a diagnosis of carcinoma.

Unguarded tricuspid orifice with pulmonary atresia: successful radiofrequency ablation of an accessory pathway in an infant

A male infant with the rare lesion of unguarded tricuspid orifice in the setting of pulmonary valve atresia, intact ventricular septum, and a hypoplastic right ventricle is described. The patient presented with cyanosis at 1 day old; transcutaneous oxygen saturations were between 20% and 30% in room air, and 60% in 100% inspired oxygen. Pre-excitation was found incidentally on the ECG and the potential for rapid antegrade conduction of atrial tachyarrhythmias, after eventual extended palliation with the Fontan procedure, was demonstrated at electrophysiological study. By 11 months old the patient was becoming increasingly cyanosed and interim palliation with a bidirectional cavopulmonary shunt was proposed. Successful radiofrequency ablation of the accessory pathway was performed before bidirectional cavopulmonary shunt, which would have prevented access to the heart via the superior vena cava. Difficulty with femoral venous access because of previous occlusion of a femoral vein was overcome by the use of 2 F pacing electrodes and a 5 F ablation catheter.

Successful use of danaparoid in treatment of heparin-induced thrombocytopenia during twin pregnancy

BACKGROUND

The treatment of heparin-induced thrombocytopenia in pregnancy is uncertain. Warfarin is contraindicated and ancrod is of unknown safety. Low-molecular-weight heparin should not be used because of cross-reactivity with unfractionated heparin. We report a case of heparin-induced thrombocytopenia during pregnancy treated successfully with danaparoid.

CASE

A 25-year-old woman pregnant with twins developed heparin-induced thrombocytopenia after starting heparin therapy for a deep vein thrombosis. Treatment was initiated with danaparoid by subcutaneous injection and was continued until the time of delivery. Treatment was completed with 6 weeks of warfarin therapy postpartum. No fetal or maternal ill effects were observed.

CONCLUSION

Danaparoid, which has low cross-reactivity for heparin-dependent antibodies and no known fetopathic effects, was used successfully to treat our patient, who developed heparin-induced thrombocytopenia during pregnancy. Danaparoid may be the treatment of choice for this difficult clinical situation in which there are limited therapeutic options.

Women, alcohol and the menstrual cycle

This review presents evidence which implicates a role for menstrual cycle phase in the response of pre-menopausal women to moderate alcohol intake. It is concluded that the majority of published studies have suffered from poor methodological design and have employed inadequate means of cycle phase identification. Contradictory and ill-founded findings have been reported. The best evidence to date suggests that women eliminate alcohol more rapidly during the mid-luteal phase of the cycle. This finding needs to be substantiated by further studies.

Association of polymorphisms of dopamine D2 receptor (DRD2), and dopamine transporter (DAT1) genes with schizoid/avoidant behaviors (SAB)

The dopaminergic system, and in particular the dopamine D2 receptor, has been implicated in reward mechanisms in the brain. Dysfunction of the D2 dopamine receptors leads to aberrant substance-seeking behaviors (ethanol, drugs, tobacco, and food) and other related behaviors (pathological gambling, Tourette's disorder, attention-deficit/hyperactivity disorder). This is the first study supporting a strong association between the dopamine D2 receptor Taq A1 allele with schizoid/avoidant behavior (SAB). Additionally, an albeit weaker association between the 480-bp VNTR 10/10 allele of the dopamine transporter (DAT1) gene with SAB was similarly found.

Iatrogenic atrioventricular bypass tract following a Fontan operation for tricuspid atresia

A 16 year old female with tricuspid atresia had undergone a Fontan operation at four years of age. Two years later she first presented with a narrow complex tachycardia which could only be partially controlled on flecainide in high doses. On electrophysiological study, the tachycardia was found to be due to atrioventricular re-entry within the surgical right atrial to right ventricular outflow tract anastomosis. Radiofrequency ablation at this site abolished the arrhythmia and she is now symptom-free on no medication.

Refractory T cell acute lymphoblastic leukemia with unusual karyotype and interesting immunophenotype

Karyotype, immunophenotype, and molecular studies are important in the evaluation of Acute Lymphocytic Leukemia as these data provide diagnostic as well as prognostic information. We present a case of acute lymphoblastic leukemia with unusual cytogenetics, 45,XY,i(7q),der(9)t(3;9)(q12;p22),del(12)(p12), :der(18)t(3;18)(p14;q22),-3. This karyotype is hypodiploid, showing loss of chromosome 3, a very rare occurrence. Hypodiploidy and translocations are suggestive of a poor clinical outcome. Cytogenetics also showed a chromosome 12p deletion which has been implicated in the oncogenesis of some acute leukemias. Immunophenotype by flow cytometry was positive for CD7 and CD10, T, and precursor B cell markers respectively. Given the specificity of CD7 for T cell processes, it was felt that the flow cytometry was more suggestive of a T cell process. Gene rearrangement studies showing a T cell receptor rearrangement helped confirm the T cell lineage of this malignancy. Hypodiploidy and T cell phenotype are indicators of poor prognosis. Interestingly this patient was refractory to two conventional chemotherapeutic protocols and finally responded to an unconventional protocol of high dose Ara C, etopside, and L asparaginase.

A clinical study of parenchymal and subdural miniature strain-gauge transducers for monitoring intracranial pressure

OBJECTIVE

Previous studies have shown that a new strain-gauge MicroSensor (Codman/Johnson & Johnson Professional, Inc., Randolph, MA) for measuring intracranial pressure (ICP) performs well in the intraventricular space. We hoped to evaluate the MicroSensor in the subdural space and the brain parenchyma, because ICP is often measured in these compartments when the ventricles are difficult to cannulate.

METHODS

Fifteen patients had simultaneous recordings of ICP from an externally transduced fluid-filled subdural catheter, a MicroSensor placed within the subdural catheter, and a nearby MicroSensor placed intraparenchymally in the right frontal lobe.

RESULTS

The total number of valid simultaneous recordings of ICP was 95,946. A highly significant correlation was found between the tissue MicroSensor ICP (TMICP) and the subdural MicroSensor ICP (SMICP) (n = 95,946; r = 0.89; P < 0.00005), the TMICP and the fluid-transduced subdural catheter ICP (r = 0.86, P < 0.00005), and the fluid-transduced subdural catheter ICP and SMICP (r = 0.88, P < 0.00005). The mean simultaneous difference between the TMICP and the SMICP was 0.1 +/- 3.8 mm Hg with no obvious bias. The fluid-transduced subdural catheter ICP was 2.8 +/- 3.9 mm Hg lower than the TMICP and 2.7 +/- 3.9 mm Hg lower than the SMICP (P < 0.0005). The mean zero drifts of the tissue and subdural MicroSensors were 0.312 and 0.475 mm Hg/d, respectively. The tissue MicroSensor recordings showed the best quality wave form with the least damping.

CONCLUSION

The strain-gauge MicroSensor is highly accurate and stable in the tissue and subdural spaces.

Fish oils and low-molecular-weight heparin for the reduction of restenosis after percutaneous transluminal coronary angioplasty. The EMPAR Study

BACKGROUND

Percutaneous transluminal coronary angioplasty (PTCA) is complicated by restenosis within 6 months in > 40% of patients. Theoretical, animal experimental, and human epidemiological and clinical trial findings have suggested that fish oils (n-3) might reduce restenosis. Low-molecular-weight heparin (LMWH) has reduced cellular proliferation and restenosis in several experimental systems.

METHODS AND RESULTS

We randomized 814 patients to fish oils (5.4 g n-3 fatty acids) or placebo a median of 6 days before PTCA and continued for 18 weeks. At the time of sheath removal, 653 patients with at least one successfully dilated lesion were randomized to LMWH (30 mg SC BID) or control for 6 weeks in a 2 x 2 factorial design. Follow-up with quantitative coronary angiography (QCA; target, 18 weeks) was interpretable on 96% of these patients. Restenosis rates per patient were for n-3, 46.5%; placebo, 44.7%; LMWH, 45.8%; and control, 45.4%. Restenosis rates per lesion were for n-3, 39.7%; placebo, 38.7%; LMWH, 38%; and control, 40.4%. At follow-up QCA, mean minimal lumen diameters were (mm) for n-3, 1.12; placebo, 1.10; LMWH, 1.12; and control, 1.10. Fifteen percent of patients permanently discontinued n-3/placebo before study completion, and 21% of patients discontinued LMWH early. There were no significant differences in the occurrences of ischemic events. Bleeding was more common with LMWH, usually was mild, and led to early discontinuation of study medication in only 0.9% of patients. Gastrointestinal side effects were more common in patients receiving n-3 than placebo.

CONCLUSIONS

There is no evidence for a clinically important reduction of PTCA restenosis in this trial by either n-3 or LMWH. Evaluation of the results for n-3 in the context of previously published data on the reduction of PTCA restenosis indicates that n-3 is not efficacious and that further trials are unwarranted.

Increased prevalence of the Taq I A1 allele of the dopamine receptor gene (DRD2) in obesity with comorbid substance use disorder: a preliminary report

In order to investigate the prevalence of the Taq I A1 allele of the dopamine receptor gene (DRD2) in obesity with and without comorbid substance use disorder, a total of 40 patients, from an outpatient neuropsychiatric clinic in Princeton, New Jersey, were genotyped for presence or absence of the Taq I DRD2 A1 allele. The primary inclusion criterion for 40 obese subjects was a body mass index (BMI) equal to or over 25 (uncharacterized); 11 obese subjects had severe substance use disorder; 20 controls had a BMI below 25; and, 33 substance use disorder (less severe) patients had a BMI below 25. The data were statistically compared with three different sets of controls divided into three separate groups (Group I, n = 20; Group II, n = 286; Group III, n = 714). They differed according to screening criteria (drug, alcohol, nicotine abuse/dependence, BMI below 25 and other related behaviours including parental history of alcoholism or drug abuse and DSM IV, Axis I and Axis II diagnoses). Groups II and III were population controls derived from the literature. The prevalence of the Taq I A1D2 dopamine receptor (DRD2) alleles was determined in 40 Caucasian obese females and males. In this sample with a mean BMI of 32.35 +/- 1.02, the A1 allele of the DRD2 gene was present in 52.5% of these obese subjects. Furthermore, we found that in the 23 obese subjects possessing comorbid substance use disorder, the prevalence of the DRD2 A1 allele significantly increased compared to the 17 obese subjects without comorbid substance use disorder. The DRD2 A1 allele was present in 73.9% of the obese subjects with comorbid substance use disorder compared to 23.5% in obese subjects without comorbid substance use disorder. Moreover, when we assessed severity of substance usage (alcoholism, cocaine dependence, etc.) increasing severity of drug use increased the prevalence of the Taq I DRD2 A1 allele; where 66.67% (8/12) of less severe probands possessed the A1 allele compared to 82% (9/11) of the most severe cases. Linear trend analyses showed that increasing use of drugs was positively and significantly associated with A1 allelic classification (p < 0.00001). These preliminary data suggest that the presence of the DRD2 A1 allele confirms increased risk not only for obesity, but also for other related addictive behaviours (previously referred to as the Reward Deficiency Syndrome) and that a BMI over 25 by itself (without characterization of macroselection or comorbid substance use disorders) is not a sufficient criterion for association with the DRD2 A1 allele.

Double-blind placebo-controlled pilot trial of acemannan in advanced human immunodeficiency virus disease

SUMMARY

We assessed the safety and surrogate markers' effect of acemannan as an adjunctive to antiretroviral therapy among patients with advanced HIV disease receiving zidovudine (ZDV) or didanosine (ddI) in a randomized, double-blind, placebo-controlled trial of acemannan (400 mg orally four times daily). Eligible patients of either sex had CD4 counts of 50-300/microl twice within 1 month of study entry and had received 26 months of antiretroviral treatment (ZDV or ddI) at a stable dose for the month before entry. CD4 counts were made every 4 weeks for 48 weeks. P24 antigen was measured at entry and every 12 weeks thereafter. Sequential quantitative lymphocyte cultures for HIV and ZDV pharmacokinetics were performed in a subset of patients. Sixty-three patients were randomized. All were males (mean age 39 years). The mean baseline CD4 counts were 165 and 147/microl in the placebo and acemannan groups, respectively; 90 percent of the patients were receiving ZDV at entry. Six patients in the acemannan group and five in the placebo group developed AIDS-defining illnesses. There was no statistically significant difference between the groups at 48 weeks with regard to the absolute change or rate of decline at CD4 count. Among ZDV-treated patients, the median rates of CD4 change (ACD4) in the initial 16 weeks were - 121 and - 120 cells per year in the placebo and acemannan groups, respectively ( p = 0.45), ACD4 from week 16 to 48 was 0 and - 61 cells per year in the acemannan and placebo groups (p = .11), respectively. There was no statistical difference between groups with regard to adverse events, p24 antigen, quantitative virology, or pharmacokinetics. Twenty-four patients, 11 receiving placebo and 13 receiving acemannan, discontinued study therapy prematurely, none due to serious adverse reactions. Our results demonstrate that acemannan at an oral daily dose of 1600 mg does not prevent the decline in CD4 count characteristic of progressive HIV disease. Acemannan showed no significant effect on p24 antigen and quantitative virology. Acemannan was well tolerated and showed no significant pharmacokinetic interaction with ZDV.

Prevalence of antibodies to Borrelia burgdorferi in European bison (bison bonasus) from Białowieza Primeval Forest

To estimate the prevalence of antibodies to borrelia burgdorferi in European bison from Białowieza Primeval Forest, a total of 79 serum samples were collected from April 1989 until December 1994. Specific antibodies to B. burgdorferi antigen were assayed using inhibition ELISA. Borrelia antibodies were possibly present in 16.4% of examined bisons (inhibition between 20 and 30%). However, higher level of antibodies, over 30% of inhibition, was found only in two animals: no. 382 and no. 273 (2.5% from 79). European bison may be a host for B. burgdorferi and this may have implications for epidemiology of Lyme borreliosis in the areas were bisons and ixodes ricinus coexist.

Primary ventricular fibrillation is associated with increased paced right ventricular electrogram fractionation

BACKGROUND

The mechanisms of spontaneous ventricular fibrillation (primary VF) in patients without structural heart disease are obscure. A new technique has shown that in patients with hypertrophic cardiomyopathy conduction of fractionated ventricular paced beats, recorded at several right ventricular sites, is prolonged in individuals who have suffered a VF arrest, and this may reveal one component of a reentrant substrate. Patients with primary VF were studied with the same methods to determine whether similar abnormalities are present in this group.

METHODS AND RESULTS

Nine patients with primary VF were studied by pacing one right ventricular (RV) site by use of a constant drive train with an extrastimulus inserted every third beat and reducing the extrastimulus coupling interval (S1S2 interval) by 1 ms on each occasion while recording at three other sites. The delay of each fractionated potential in the high-pass-filtered electrograms in response to the extrastimulus was determined and used to form conduction curves of delay versus the S1S2 interval. These curves were repeated by pacing each RV site in turn and recording from the other three sites. The curves were characterized by determining the S1S2 interval at which electrogram components increased in delay by 0.75 ms/20 ms reduction in S1S2 interval and the increase in electrogram duration between a coupling interval of 350 ms and 1 ms above refractoriness. Seven control patients were studied using the same method. The mean increase in electrogram duration in VF patients was 13 ms (range, 3 to 23 ms) compared with 4 ms (range, -2 to 14 ms) in unaffected control patients. The extrastimulus coupling interval at which delay increased was 318 ms (range, 293 to 334 ms) in VF patients and 274 ms (range, 265 to 284 ms) in control patients (P < .01). There was no difference between the number of fractionated potentials in VF patients and control patients.

CONCLUSIONS

In primary VF patients, the individual potentials within fractionated electrograms have increased delays when compared with control patients. This may identify one component of a reentrant arrhythmic substrate.

Didanosine compared with continued zidovudine therapy for HIV-infected patients with 200 to 500 CD4 cells/mm3. A double-blind, randomized, controlled trial. Canadian HIV Trials Network Protocol 002 Study Group

OBJECTIVE

To compare the safety and efficacy of didanosine with that of continued zidovudine therapy in persons with human immunodeficiency virus (HIV) infection who had received zidovudine for at least 6 months and had CD4 cell counts of 200 to 500 CD4 cells/mm3.

DESIGN

Double-blind, randomized controlled trial.

SETTING

10 Canadian university-affiliated specialty clinics.

PATIENTS

246 patients were assigned to receive standard doses of either zidovudine or didanosine.

OUTCOME MEASURES

The primary clinical end point was the occurrence of a new, previously undiagnosed acquired immunodeficiency syndrome (AIDS)-defining illness or death.

RESULTS

245 of 246 patients were eligible (118 receiving didanosine and 127 receiving zidovudine). Sixty-six percent were asymptomatic, 30% had AIDS-related complex, and 4% had AIDS. The median baseline CD4 count was 320 cells/mm3. The median previous duration of zidovudine therapy was 471 days. Nine new AIDS-defining illnesses developed during the study; all but one were in the zidovudine group (relative risk, 7.9 [95% CI, 1.0 to 63.3; P = 0.02]). A change to didanosine led to a statistically significant increase in CD4 counts by week 2 that persisted until the end of the study at week 48 (P < or = 0.01). Viral sensitivity studies (done in 102 patients) showed that 28% of the zidovudine group and 21% of the didanosine group had high-level in vitro resistance to zidovudine (50% inhibitory concentration greater than 0.8 microM) at baseline (P = 0.49). Only one patient in the didanosine group developed high-level resistance to zidovudine during the study. In the zidovudine group, the cumulative probability of developing high-level resistance to zidovudine was 59% at 1 year (P = 0.01). Abdominal pain, leukopenia, and neutropenia were more frequent in the zidovudine group, and hyperuricemia was more frequent in the didanosine group (P < 0.05).

CONCLUSION

In clinically stable patients with 200 to 500 CD4 cells/mm3 who had tolerated zidovudine for at least 6 months, a change to didanosine led to a decrease in the rate of disease progression, a sustained increase in CD4 counts, and a decrease in the chances of developing high-level resistance to zidovudine. Both drugs were generally well tolerated.

Serum lysozyme level in the European bison, Bison bonasus (L.)

From 168 European bison divided into four groups (group 1, 0-3-year-old males; group 2, 0-3-year-old females; group 3, mature bulls, over 2 years old; group 4, mature cows, over 3 years old) the serum lysozyme level was studied. The mean lysozyme level varied from 3.91 micrograms/ml in young males (group 1) to 4.02 micrograms/ml in young females (group 2) and mature bulls (group 3); the range was from 2.10 to 6.40 micrograms/ml (only in a few animals). Statistically significant differences between months were found only in young males (group 1).

Safety profile of didanosine among patients with advanced HIV disease who are intolerant to or deteriorate despite zidovudine therapy: results of the Canadian Open ddI Treatment Program

The aim of this study was to ascertain the safety profile of didanosine (Videx; ddI) within the Canadian Open Treatment Program. Symptomatic HIV+ subjects with AIDS or ARC or CD4 < 200/mm3 were eligible to receive didanosine if they were either (a) intolerant to zidovudine (Retrovir, ZDV) or (b) deteriorating despite ZDV therapy. The dose of didanosine (powder formulation) was based on body weight as follows: > or = 75 kg, 375 mg b.i.d.; 50-74 kg, 250 mg b.i.d.; 35-49 kg, 167 mg b.i.d. Participants were monitored with physical examinations and prespecified laboratory studies by their treating physicians on a monthly basis. Follow-up data were collected in a central database through five regional coordinators. A total of 168 physicians across Canada participated in the program, and 825 subjects who started didanosine after July 1, 1990, were included in the analysis. Of these, 97% were male, 88% homosexual, and 59% had a prior diagnosis of AIDS. Reasons for enrolling was ZDV intolerance in 39%, failure in 25%, both in 32%, and other in 4%. Data were prospectively collected until July 31, 1991. Total follow-up was 3,440 patient-months and median follow-up was 4.3 months. A total of 78 deaths were reported, 44 of which occurred within a month after the last dose of didanosine. Causes of death included AIDS-related unspecified causes (13 patients), MAC (11), wasting (7), AIDS-related CNS involvement other than OI's (7), Kaposi's sarcoma (7), Pneumocystis carinii pneumonia (6), sudden death, including suicides and accidents (6), lymphoma (5), toxoplasmosis (4), cryptococcosis (4), cytomegalovirus (3), unspecified causes (2), tuberculosis (1), PML (1), and disseminated histoplasmosis (1). Didanosine was discontinued in 140 (17%) subjects during the study period due to adverse events.(ABSTRACT TRUNCATED AT 250 WORDS)

HIV-1 gp120/160 expressing transfected cell clones to evaluate the antibody-dependent cellular cytotoxicity (ADCC) during the course of HIV-1 infection

Transfection by electroporation of the CEM.NKR cell line with a plasmid containing the HIVNL43 gp160 gene resulted in the establishment of HIV-1 gp120/160 expressing CEM.NKR cell clones. The cell-surface expression of the recombinant viral envelope is stable and does not lead to syncytium formation among a substantial number of cells expressing envelope glycoprotein, suggesting that these cells are suitable as targets to monitor HIV-specific ADCC activities with the stage or the progression of HIV-1 disease. By using these cells, the ability of sera from HIV-1 seropositive individuals to mediate ADCC against HIV-1 gp120/160 transfected cells in an antigen-specific manner was established. Approximately 63% of the HIV-infected individuals representing all stages of infection have virus-specific ADCC antibodies. Moreover, sera from healthy seropositive (CDC class II) subjects mediated substantially higher levels of ADCC activity (25.7 +/- 11.5%) than did sera from individuals in CDC class III (10.3 +/- 8.9%) or IVC1 (6.4 +/- 8.1%). The mean ADCC activity for the sera from the seronegative volunteers was 2 +/- 1.3%. The correlation between the ADCC level and CD4 cell depletion remains uncertain. Therefore, the established transfected cell line may be used to probe the role of gp120/160-specific ADCC activity in the development of AIDS and may also prove useful in screening human and murine monoclonal antibodies with potential ADCC activity. Such monoclonals may be useful for future immunotherapeutic agents in conjunction with antiviral chemotherapy.

Radiology workload--a solution reviewed after 14 years' experience

A method of controlling the radiological workload in a district general hospital, based on an estimation of the reasonable capacity of the department, was introduced in 1978. Measurement of the number of examinations performed compared with the estimated reasonable capacity shows that the method has been effective. An immediate 25% reduction in examinations was followed by a workload which varied between -4% and +16% of the capacity. An increase in the proportion of complex examinations in the period under review has been recognized. The method has encouraged referring doctors to exercise restraint and adopt guidelines, and helped persuade managers to increase capacity by appointing additional radiologists.

Alcohol problems in employment: epidemiology and responses

A review is presented of evidence related to the epidemiology of alcohol-related problems in employment and of policies to prevent or curb such problems. It is concluded that, although alcohol use is associated with accidents, absenteeism and inefficiency, epidemiological data from most countries are scarce. Available evidence is so limited that estimates of the extent or cost of alcohol-related problems in the workplace are of dubious value. National responses to alcohol problems in employment have been variable. A significant proportion of relevant published evidence relates to the U.S.A. It appears that even there very few workplace initiatives have been subjected to rigorous assessment. Limited evidence suggests that Employee Assistance Programmes for problem drinkers have reduced subsequent health-care costs.

Adrenoceptor-linked [45Ca2+] uptake in platelets from diabetic rats: a model for human platelets

Adrenoceptor-linked 45 calcium uptake was investigated in platelet from diabetic rats (hyperglycaemic, streptozotocin-induced, of 60 days duration). Basal uptake was markedly enhanced in platelets from diabetic rats compared with controls. However, whereas adrenaline-stimulated uptake was unchanged, isoprenaline-stimulated uptake was significantly reduced and noradrenaline-stimulated uptake significantly increased. These latter data indicate that there are differential alterations of adrenoceptor subtypes in diabetes (i.e. an increase in alpha- but decrease in beta-adrenoceptors). These changes in calcium uptake and in adrenoceptor activity may relate to altered platelet function known to occur in experimental diabetes. Furthermore, the similarity of the rat platelet with that of the human (in terms of absolute calcium uptake, responses to agonists and changes in diabetes), renders the rat platelet an appropriate model for studying calcium dynamics and linked adrenoceptors in diabetes.

Influence of environmental factors on the deep and skin temperature in the European bison, Bison bonasus (L.)

1. In 43 European bison divided into three groups (Group A, 3-8-month-old calves; Group B, 18-month-7-year-old young bison; Group C, 12-24-year-old bison) the rectal, humerus region and abdomen region temperatures were measured. 2. The experiments were carried out in winter months, from mid-December to mid-March. 3. The mean rectal temperatures changed from 38.55 degrees C in calves to 38.15 degrees C in the oldest bison. 4. The mean temperatures of the humerus region changed from 20.69 degrees C in calves to 21.49 degrees C in older bison. 5. The mean temperatures of the abdomen region changed from 20.79 degrees C in calves to 22.17 degrees C in older bison (Gr. B). 6. The cluster analysis divided the bison into four groups named hot, warm, cool and cold bison. 7. Only air temperature measured 2 m above the ground and snow cover influenced the integrated bison temperature. Age, sex and mass as well as some environmental factors had no influence. 8. Measurements made 1 to nearly 4 hr after a bison's death showed a drop in rectal temperature and mostly increases in temperatures of the humerus and abdomen regions.

Use of endoscopic biopsies and microelectrodes to study human gastric acid secretion in vitro

We have investigated the possibility of measuring acid secretion from human gastric mucosa in vitro as a potential pharmacological preparation. We used open-ended 10 microns-tip, lix-based glass microelectrodes to measure the pH of the mucus layer of gastric biopsies superfused with a HEPES buffered solution in an organ bath. With no drugs added the pH of the mucus layer of biopsies from the body of the stomach stayed constant but the pH of antral biopsies fell slightly by a median of 0.12 pH units over 80 min (P < 0.05). Stimulation of the biopsies with 1-100 microM histamine produced a dose-dependent decrease in pH which was significantly greater in biopsies from the gastric body than from the antrum. 500 pM pentagastrin produced a median fall in pH of 1.20 (P < 0.01) which was prevented by the prior addition of 100 microM omeprazole or 10 microM ranitidine. Omeprazole or ranitidine alone produced slight rises in the median pH of 0.47 (P < 0.05) and 0.26 (P < 0.05) units respectively. Those biopsies which were infected with Helicobacter pylori had a slightly elevated initial pH of about 0.2 of a pH unit (P < 0.05). This novel system provides a means to study human gastric acid secretion in vitro and may be valuable in the testing of new drugs on the stomach.

Effect of buflomedil on in vitro prostacyclin and endothelin synthesis by vascular (rat and human) and penile (rat) tissue and calcium uptake by isolated human platelets

The effect of buflomedil, a vasodilator, on: (a) in vitro prostacyclin (PGI2) synthesis by the rat aorta and penis, human cultured endothelial cells (HUVECs) and human iliac artery, (b) endothelin synthesis by HUVECs and (c) 45Ca2+ uptake by isolated human platelets was investigated. Buflomedil had no effect on PGI2 synthesis by rat aorta, iliac artery or HUVECs (short or long-term incubations). However, buflomedil inhibited noradrenaline- (but not arachidonate- or ionophore A23187-) stimulated PGI2 synthesis. Buflomedil had a weak stimulatory effect on PGI2 synthesis by the isolated rat penis, but this was not inhibited by cholinergic antagonists. Buflomedil (except at supra-therapeutic concentrations) exerted no effect on endothelin release by HUVECS. Buflomedil inhibited 45Ca2+ uptake by human platelets when stimulated with collagen and adrenaline, but not when stimulated with calcium ionophore A23187. These data demonstrate that buflomedil has no deleterious effect on the enzymes that control vascular PGI2 synthesis. The data also adds to the evidence that buflomedil is an alpha-adrenoceptor blocker and has stimulatory effects on penile PGI2 synthesis. Both of these properties may prove useful in the treatment of impotence. The specific inhibition of 45Ca2+ uptake consolidates that buflomedil has some calcium-channel-blocking properties which may explain, at least in part, its vasodilator and antiplatelet properties. Buflomedil may prove beneficial in the treatment of impotence via three mechanisms: (a) stimulation of penile PGI2 synthesis (b) alpha-adrenoceptor blockade and (c) calcium-mobilization-blocking properties.

Influence of recognition errors of computerised analysis of 24-hour electrocardiograms on the measurement of spectral components of heart rate variability

Spectral methods for the assessment of heart rate variability (HRV) in 24-h electrocardiograms (ECG) are believed to require visual verification and manual editing of the computerised recognition of the ECG. This study investigated the effect of the recognition errors of computerised ECG recognition on two methods providing spectral HRV indices: (a) Fast Fourier Transformation (FFT); and (b) peak-to-trough analysis (PTA). Both methods were used to measure HRV spectra in 24-h ECGs recorded in 557 survivors of acute myocardial infarction. Each ECG was analysed using the Marquette 8000 Holter system and spectral HRV analyses were performed both prior to and after manual verification of the automatic ECG analysis. The FFT and PTA methods were used to calculate the low (0.04-0.15 Hz), medium (0.15-0.40 Hz) and high (0.40-1.00 Hz) HRV spectral components. For each method and for each spectral component, the rank correlations between the results obtained from unedited and edited ECG recognition were calculated. The correlations between the corresponding spectral components provided by the FFT and PTA methods applied to the edited recognitions were also calculated. Both methods were substantially affected by recognition errors. The FFT method was more sensitive to the misrecognition than the PTA method. The inter-method correlations were higher for the high and medium spectral components than for the low spectral component. The study suggests that spectral HRV analysis should be performed only on carefully verified and manually corrected recognitions of long-term electrocardiograms.