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Biomedical subjects

R Kaiser

Publications and source records attributed to R Kaiser.

At least 55 records · Page 3Linked to original sources
PubMed2002

Coherent light transport in a cold strontium cloud.

We study light coherent transport in the weak localization regime using magneto-optically cooled strontium atoms. The coherent backscattering cone is measured in the four polarization channels using light resonant with a J(g) = 0-->J(e) = 1 transition of the strontium atom. We find an enhancement factor close to 2 in the helicity preserving channel, in agreement with theoretical predictions. This observation confirms the effect of internal structure as the key mechanism for the contrast reduction observed with a rubidium cold cloud [G. Labeyrie et al., Phys. Rev. Lett. 83, 5266 (1999)]. Experimental results are in good agreement with Monte Carlo simulations taking into account geometry effects.

Journal Article↗
PubMed2002

Relationship between adverse effects of antipsychotic treatment and dopamine D(2) receptor polymorphisms in patients with schizophrenia.

Extrapyramidal adverse symptoms (EPS) represent a major type of adverse events in treatment with typical antipsychotic drugs which share high affinity to the dopamine D(2) receptor (DRD2). Genetic variants of this receptor may modulate the therapeutic response and the severity of adverse symptoms of antipsychotics. We analyzed nine known polymorphisms of the DRD2 in 665 schizophrenic patients with European Caucasian ethnic background and compared the intensity of acute dystonia, extrapyramidal symptoms, akathisia, and tardive dyskinesia between carriers of different DRD2 genotypes. In a subgroup of 40 patients with most severe extrapyramidal symptoms we sequenced the coding region including the exon-intron junctions of the DRD2 gene. Functionally relevant DRD2 amino acid variants (Ser(310), Cys(311)) were rare or were not found at all (Ala(96)). Complete sequence analysis of sufferers from the most severe adverse effects revealed two new intronic polymorphisms and a silent polymorphism in exon 7, but no new amino acid variants beyond those which are already known. We found no significant association between these polymorphisms and the intensity of the different types of adverse neurologic effects of the antipsychotics. These results were obtained by correlating adverse events with each of the nine single nucleotide polymorphisms and by correlation with the estimated haplotypes. In conclusion, genetic variations in the DRD2 gene were no major predictors of the individually variable adverse effects from antipsychotic treatment in Caucasian schizophrenic patients.

Adolescent↗
PubMed2001

Chaos-assisted tunneling with cold atoms.

In the context of quantum chaos, both theory and numerical analysis predict large fluctuations of the tunneling transition probabilities when irregular dynamics is present at the classical level. Here we consider the nondissipative quantum evolution of cold atoms trapped in a time-dependent modulated periodic potential generated by two laser beams. We give some precise guidelines for the observation of chaos-assisted tunneling between invariant phase space structures paired by time-reversal symmetry.

Journal Article↗
PubMed2001

Assessment of deaths attributable to air pollution: should we use risk estimates based on time series or on cohort studies?

Epidemiologic studies are crucial to the estimation of numbers of deaths attributable to air pollution. In this paper, the authors present a framework for distinguishing estimates of attributable cases based on time-series studies from those based on cohort studies, the latter being 5-10 times larger. The authors distinguish four categories of death associated with air pollution: A) air pollution increases both the risk of underlying diseases leading to frailty and the short term risk of death among the frail; B) air pollution increases the risk of chronic diseases leading to frailty but is unrelated to timing of death; C) air pollution is unrelated to risk of chronic diseases but short term exposure increases mortality among persons who are frail; and D) neither underlying chronic disease nor the event of death is related to air pollution exposure. Time-series approaches capture deaths from categories A and C, whereas cohort studies assess cases from categories A, B, and C. In addition, years of life lost can only be derived from cohort studies, where time to death is the outcome, while in time-series studies, death is a once-only event (no dimension in time). The authors conclude that time-series analyses underestimate cases of death attributable to air pollution and that assessment of the impact of air pollution on mortality should be based on cohort studies.

Air Pollutants↗
PubMed2001

Invisible mean field dynamos.

We provide examples of alpha(2) dynamos in spheres which generate magnetic fields that are confined to the conductor and are therefore undetectable in the surrounding vacuum.

Journal Article↗
PubMed2001

Paraneoplastic polyneuropathy preceding the diagnosis of Hodgkin's disease and non-small cell lung cancer in a patient with concomitant Borrelia burgdorferi infection.

A patient with painful peripheral neuropathy is presented, whose symptoms were thought to result from an infection with Borrelia burgdorferi sensu lato. Investigations of the cerebrospinal fluid for signs of inflammation and borrelial antibodies were negative, and the patient did not benefit from repeated antibiotic treatment. Electrophysiologic studies and sural nerve biopsy showed axonal neuropathy consistent with a paraneoplastic syndrome. Further workup revealed mediastinal Hodgkin's disease (HD; nodular sclerosing subtype) Ann Arbor stage II and non-small cell cancer of the lung (stage T1N0M0). Surgical resection of the lung cancer and combined chemo- and radiotherapy for HD resulted in complete remission of both malignancies. While the preexisting neurologic symptoms persisted during treatment, neurography showed some improvement of the distal nerves. During radiation therapy the patient developed transient left-sided brachial plexopathy. This case illustrates that the diagnosis of borreliosis in patients with isolated painful peripheral neuritis cannot be based solely upon positive IgG titers and supports the requirement for a thorough workup for an underlying--potentially curable--disease. In addition, singular pulmonary lesions in the setting of HD should be suspected to have a separate cause.

Adult↗
PubMed2001

Differences in substance abuse patterns: multiple drug abuse alone versus schizophrenia with multiple drug abuse.

OBJECTIVE: To compare the lifetime consumption patterns of patients with schizophrenia and multiple substance abuse and multiple substance abusers without schizophrenia. METHOD: Two hundred and thirty in-patients of a specialized rehabilitation facility for young drug abusers were assessed with regard to their lifetime consumption patterns of 16 different classes of psychoactive drugs. While 110 patients had no diagnosis of a schizophrenic disorder, 120 patients had a comorbidity of multiple substance abuse and schizophrenia. RESULTS: Comorbid patients reported a higher lifetime consumption of hallucinogens, whereas multiple substance abusers without schizophrenia showed a higher lifetime consumption rate of cocaine. CONCLUSION: The differences found in lifetime consumption patterns between comorbid patients and substance abusers without psychotic disorder do not support the so-called self-medication hypothesis. Instead, the differences in lifetime consumption of certain drugs might be a result of lower social competence and standing in schizophrenic patients and lower ability to procure certain illicit drugs.

Adult↗
PubMed2001

Serotonin transporter polymorphisms: no association with response to antipsychotic treatment, but associations with the schizoparanoid and residual subtypes of schizophrenia.

The human serotonin transporter gene (5-HTT) demonstrates two polymorphisms with possible functional impact: a 44-bp insertion/deletion polymorphism of the promoter region and a 17-bp variable number of tandem repeat polymorphism (VNTR) in intron 2 (STin2). Such genetic polymorphisms in the serotoninergic system may increase the susceptibility to schizophrenia or may serve as predictors of therapeutic response. We therefore analyzed these polymorphisms as susceptibility factors for schizophrenia by comparison of 684 schizophrenic inpatients with 587 healthy controls. We furthermore compared the therapeutic outcome of schizophrenic patients differentiated by the 5-HTT genotypes. Schizo-affective patients were more frequently homozygous for the 44-bp insertion allele (Odds ratio, OR: 1.6, 95% confidence interval, CI: 1.1--2.3, P < 0.03) than were all other schizophrenic patients and controls. The 17-bp VNTR alleles found were: STin2.7, 9, 10, and 12. Sequence analysis revealed seven different sequence motifs with an invariable arrangement. Patients with schizo-paranoid schizophrenia were more frequently homozygous for the STin2.12 allele than were controls (OR: 1.4, CI: 1.1--1.8, P < 0.007) and all other schizophrenic patients (OR: 1.6, CI: 1.2--2.3). The STin2.9 allele represented a risk factor for the residual subtype of schizophrenia (OR: 6.4, CI: 2.5--16.2, P < 0.001). On the basis of global clinical impressions, as well as measurements with the positive and negative syndrome scale we found no association of the polymorphisms with therapeutic response. In conclusion, the 44-bp polymorphism may be associated with the schizo-affective and the 17-bp VNTR with the residual and schizo-paranoid subtype of schizophrenia, findings which require further biochemical and epidemiological confirmation.

Adolescent↗
PubMed2001

[Surgery of the lateral accessory saphenous vein].

Confusion exists regarding the right surgical strategy for therapy of isolated varicosis of the lateral accessorian saphenous vein (LASV) resulting from an incompetent valve at the crosse without concomitant reflux into the long saphenous vein (LSV). In a retrospective study 30 patients with isolated varicosis of the LASV were examined 3 years after surgical treatment. In this study the first segment of the LSV was removed after resection of the LASV. 64% of our patients were free of recurrence after 3 years. 25% had partial reflux from the Boyd perforans vein and only 9% of the patients had a complete reflux in the LSV. Based on our results it is justified not to remove the LSV in cases of isolated varicosis of the LASV.

Adult↗
PubMed2001

Avidity determination of Borrelia burgdorferi-specific IgG antibodies in Lyme disease.

The avidity indices of Borrelia burgdorferi-specific IgG antibodies were estimated using ELISA in sera from patients with different stages of Lyme disease. In addition, sera from healthy students with proof of borrelial-specific IgG antibodies from standard serology were tested. Low avidity indices were detected predominantly in sera from patients with early-stage Lyme disease [erythema migrans (EM); n = 25]. High avidity indices were found in healthy students (n = 72) and in most of the patients with neuroborreliosis (NB; n = 44) and chronic late-stage Lyme disease [acrodermatitis chronica atrophicans (ACA); n = 36]. In conclusion, early-stage Lyme disease (EM) could be differentiated from advanced and chronic stages (NB, ACA) and from "seropositive" healthy persons using avidity determination in the majority of patients in this study.

Antibody Affinity↗
PubMed2001

Heat-related death and mental illness during the 1999 Cincinnati heat wave.

During a 1999 heat wave in Cincinnati, Ohio, the Hamilton County Coroner reported 18 heat-related deaths. The Centers for Disease Control and Prevention and the Cincinnati Department of Health conducted a case-control study using surrogate case information and first-person control information to identify risk factors for mortality during the heat wave. Surrogate data were supplemented by systematic death scene investigation reports and comprehensive toxicologic screens, important sources of data that are routinely collected by the Hamilton County Coroner's Office. The study included 17 case subjects and 34 controls from the decedents' neighborhood. Among 17 case subjects, 8 (47.1%) had mental illness (odds ratio [OR], 14.0; 95% confidence interval [CI], 1.8-633). There was a suggestion of an interaction between age and mental health. A working air-conditioner was the strongest protective factor (OR, 0.03; 95% CI, 0-0.2). Toxicologic screening indicated that case subjects with reported mental illness and a prescription for psychotropic drugs may not have been medication compliant. Three decedents lived in group homes for people with mental illness, indicating that opportunities for prevention may have been missed. Systematic death investigations, including toxicologic screening, provide valuable information about the circumstances of heat-related death, particularly the role of medication compliance as a risk factor. Prevention programs during heat waves should target people with mental illness, especially those who take psychotropic medication.

Adult↗
PubMed2001

Heat-related mortality in selected United States cities, summer 1999.

As part of a public health response to severe heat waves in the midwestern and northeastern United States in the summer of 1999, the authors actively solicited the number of heat-related deaths from 38 medical examiner and coroner jurisdictions comprising 35 metropolitan areas to enumerate heat-related deaths in areas affected by heat waves. They also determined the usefulness of these data for surveillance and rapid investigation of heat-related deaths. A total of 334 heat-related deaths were reported during the study period of July 1 - August 31. Minor changes in data collection and diagnostic criteria in some medical examiner and coroner jurisdictions would allow for greater comparability among jurisdictions. The National Association of Medical Examiners' position paper on heat-related mortality diagnosis provides important guidance to medical examiners and coroners regarding the certification of heat-related deaths and may require some refinement to address certain issues. Among these are certifying manner of death and classifying potential causes of heat-related death not involving hyperthermia or heat stroke, but where heat is a potential contributing factor to death. Medical examiners and coroners are an important resource for heat-related mortality research, and improvements in data collection and reporting could yield tremendous benefits to our understanding of and interventions for heat-related deaths.

Cause of Death↗
PubMed2001

Transient loss of T-cell reactivity in a patient with hepatitis C virus reinfection.

BACKGROUND/AIMS: Self-limited acute hepatitis C virus (HCV) infection with spontaneous recovery is only rarely observed in clinical practice. All existing studies correlate strong cellular immune responses to the recovery from HCV infection. CASE REPORT: Here, we present a 49-year-old haemophiliac, who had successfully recovered from an acute hepatitis, which was classified retrospectively as HCV infection based on his antibody profiles. This patient was reinfected with HCV 18 years later from an exogenous source, and successfully recovered from this reinfection within 2 months. After his first hepatitis the patient displayed strong cellular responses against recombinant HCV proteins. During reinfection, T-cell proliferation was markedly reduced, while HCV antibody titres increased. However, E2 antibodies were consistently not detectable. T-cell proliferation returned to the pre-reinfection level only several months after loss of viraemia. DISCUSSION: Our observations resulted in the unexpected finding that our patient cleared HCV reinfection despite an apparent loss of his pre-existing T-cell reactivity in the peripheral blood.

Hemophilia A↗
PubMed2001

Blood lead levels of primary school children in Dhaka, Bangladesh.

Dhaka, Bangladesh, has one of the highest air lead levels in the world. In February 2000, we evaluated children at five primary schools in Dhaka to determine blood lead (BPb) levels, sources of environmental exposure, and potential risk factors for lead poisoning. Selected schools represented a range of geographic and socioeconomic strata. A total of 779 students 4-12 years of age participated. The mean BPb level was 15.0 microg/dL (range 4.2-63.1 microg/dL). Most students (87.4%) had BPb levels above the Centers for Disease Control and Prevention's level of concern (10 microg/dL). Elevated BPb levels correlated with soil eating [odds ratio (OR) = 3.31; 95% confidence interval (CI), 1.30-8.39], low parental education (OR = 2.72; 95% CI, 1.97-3.75), living close to major roads (OR = 2.30; 95% CI, 1.23-4.29), and increasing age (OR = 1.11; 95% CI, 1.06-1.16). BPb levels measured were similar to those in other countries that use leaded gasoline. No other potential sources of lead exposure were consistently identified. Combustion of leaded gasoline is the main source of lead exposure in Dhaka, resulting in ubiquitous contamination of the environment. The increase in BPb levels with age, a finding contrary to observations in the United States and Australia, may be related to increased outdoor activities. The Bangladeshi government recently announced a plan to eliminate leaded gasoline. Baseline BPb surveys are critical to develop and evaluate intervention policies. Strategies to reduce BPb levels need to address variations in socioeconomic status, construction type and location of housing, and levels of hygiene.

Air Pollution↗
PubMed2001

Collaboration, cholera, and cyclones: a project to improve point-of-use water quality in Madagascar.

In November 1999, CARE Madagascar, Population Services International (PSI), and the Centers for Disease Control and Prevention (CDC) selected 30 poor communities in urban Antananarivo as the target population for launch of the Safe Water System. The system consists of behavior change techniques along with point-of-use treatment and safe storage of water. The project was launched in March 2000, ahead of schedule, because a cholera epidemic struck Madagascar in January. Because of the enormous demand created by the cholera epidemic and by 3 cyclones that followed in the next 3 months, the project grew to national scale in less than a year. The combination of community mobilization and social marketing resulted in increased demand for and use of the Safe Water System.

Cholera↗
PubMed2001

Impact of the safe water system on water quality in cyclone-affected communities in Madagascar.

Cyclone Hudah struck the northeastern coast of Madagascar in the spring of 2000. Over a 5-month period, 11 700 relief kits consisting of bottles of water disinfectant and foldable jerry cans were distributed to the affected population. Five months after the cyclone, a survey was conducted in 12 villages to determine the impact of these relief kits on water quality. Seventy-six percent of the surveyed households reported using jerry cans, and 65% reported using the disinfectant. Stored water in households using both products had significantly less microbiological contamination than stored water in other households. To improve the prospects for a sustainable intervention, the response plan for future disasters should incorporate a transition to recovery and development, including formative research into local customs, beliefs, and water handling habits, and funding support to initiate social marketing.

Disasters↗
PubMed2001

Enzyme linked immunosorbent assay using recombinant HuD-autoantigen for serodiagnosis of paraneoplastic neurological syndromes.

OBJECTIVES: The aim of this study was to evaluate the suitability of an ELISA employing purified recombinant HuD antigen, for detection of specific anti-HuD antibodies in sera and cerebrospinal fluid (CSF) from patients with paraneoplastic neurological syndromes (PNS). MATERIAL AND METHODS: The cutoff for optical density readings was estimated by testing of 145 sera from healthy subjects. Sera from 17 patients with paraneoplastic neurological syndromes (PNS) and evidence of a clear anti-Hu band pattern in an immunoblot employing human cerebellar crude extract as antigen were tested. RESULTS: All 17 sera from patients with PNS revealed a clear positive result in the HuD-ELISA, demonstrating a sensitivity of 100%. Two out of 150 sera from patients with various infectious, autoimmune and neoplastic diseases (excluding PNS) showed a borderline result in the HuD-ELISA. This reveals a specificity of more than 98%. In addition 10 serum/CSF pairs from patients with anti-Hu-syndrome were adjusted to equal IgG concentrations and were tested in parallel in the HuD-ELISA. A specific antibody index (AI=ODCSF/ODserum) over 1.5 indicates intrathecal antibody synthesis. Six of ten patients revealed an AI >1.5, one was borderline (AI=1.5), and three had an AI in the range of 0.9-1.2. There appears to be a correlation between elevated AIs (>1.5) and presence of oligoclonal bands in the CSF. CONCLUSION: Due to its high specificity and sensitivity the recombinant HuD-ELISA is a suitable test for detection of anti-HuD antibodies in patients with putative PNS. In addition, the HuD-ELISA seems to be appropriate for the detection of specific intrathecal HuD-antibody synthesis.

Adult↗