Health care for the homeless: a family medicine perspective

Many factors contribute to the health problems of homeless persons, including exposure to adverse weather, trauma and crime, overcrowding in shelters, unusual sleeping accommodations, poor hygiene and nutritional status, alcoholism, drug abuse and psychiatric illness. It is common for homeless adults to have skin ailments, respiratory infections, traumatic injuries and chronic gastrointestinal, vascular, dental and neurologic disorders. Homeless children may have respiratory, ear and skin diseases, as well as special problems, including failure to thrive, developmental delay, neglect and abuse. Important questions to ask during history-taking include questions about sleeping conditions, sources of food, past psychiatric problems and substance abuse, and sources of social support. Special attention should be given to examination of the skin, teeth and feet. Supplemental food, immunizations, psychologic counseling and social service referrals should be considered for homeless pediatric patients.

In vitro analysis of mutant LexA proteins with an increased rate of specific cleavage

Specific cleavage of LexA repressor plays a crucial role in the SOS response of Escherichia coli. In vivo, cleavage requires an activated form of RecA protein. However, previous work has shown that the mechanism of cleavage is unusual, in that the chemistry of cleavage is probably carried out by residues in the repressor, and not those in RecA; RecA appears to facilitate this reaction, acting as a coprotease. We recently described a new type of lexA mutation, a class termed lexA (IndS) and here called IndS, that confers an increased rate of in vivo cleavage. Here, we have characterized the in vitro cleavage of these IndS mutant proteins, and of several double mutant proteins containing an IndS mutation and one of several mutations, termed Ind-, that decrease the rate of cleavage. We found, first, that the autodigestion reaction for the IndS mutant proteins had a higher maximum rate and a lower apparent pKa than wild-type LexA. Second, the IndS mutations had little or no effect on the rate of RecA-mediated cleavage, measured at low protein concentrations, implying that the value of Kcat/Km was unaffected. Third, the rate of autodigestion for the double-mutant proteins, relative to wild-type, was about that rate predicted from the product of the effects of the two single mutations. Finally, by contrast, these proteins displayed the same rate of RecA-mediated cleavage as did the single Ind- mutant protein. We interpret these data to mean that the IndS mutations mimic to some extent the effect of RecA on cleavage, perhaps by favoring a conformational change in LexA. We present and analyze a model that embodies these conclusions.

The decline in geriatric long stay beds: who remains?

A day census of all long-term hospital patients in the Canterbury geriatric service area was carried out in 1984 (when there were 127 beds) and repeated in 1989 (when there were 66 beds). The patients in the 1989 census were more confused and physically more dependent than those in 1984. Comparison with residents in local residential and nursing homes in 1987 shows that a higher proportion of long-term hospital patients had severe mental and physical disability. There is a hard core of patients who are difficult to place outside hospital. This has predictable resource implications and in Canterbury such patients will continue to occupy National Health Service beds as there are no practicable alternatives.

Hematogenous dissemination of Mycobacterium tuberculosis in patients with AIDS

Proof of hematogenous dissemination of Mycobacterium tuberculosis was initially reported in the early 1900s and was noted to be most frequent in patients with miliary tuberculosis. More recently, M. tuberculosis bacteremia has been reported in human immunodeficiency virus (HIV)-infected patients. We describe 13 adult HIV-infected patients in whom hematogenous M. tuberculosis dissemination was evident. Although for most patients whose bone marrow aspirate cultures yielded M. tuberculosis a chest roentgenogram revealed a miliary pattern, roentgenograms for those with M. tuberculosis bacteremia usually revealed evidence of lobar or diffuse infiltrates. Most patients with M. tuberculosis bacteremia had other risk factors for M. tuberculosis, and many had a rapid death, suggesting acute fulminant infection. Our own experience suggests that there are various syndromes associated with hematogenous dissemination in patients infected with M. tuberculosis.

Molecular characterization of biologically diverse envelope variants of human immunodeficiency virus type 1 derived from an individual

The envelope genes of six viruses derived from a single sampling from an individual chronically infected with human immunodeficiency virus type 1 (RJS-4) have been analyzed. Here we present the nucleotide and predicted amino acid sequences of these variants and show a correlation between biological properties and disturbance of the envelope reading frame.

Mutant LexA proteins with an increased rate of in vivo cleavage

LexA repressor of Escherichia coli is inactivated by a specific cleavage reaction that requires activated RecA protein in vivo. This cleavage reaction can proceed in vitro in the presence of activated RecA or as an intramolecular RecA-independent reaction, termed autodigestion, that is stimulated by alkaline pH. Here we describe a set of LexA mutant proteins that undergo a greatly increased rate of specific cleavage in vivo, compared with wild-type LexA. Efficient in vivo cleavage of these mutant proteins also took place without RecA. Several lines of evidence suggest that cleavage occurred via a mechanism similar to autodigestion. These mutations changed Gln-92, which lies near the cleavage site, to tyrosine, phenylalanine, or tryptophan. The latter mutation increased the rate of cleavage approximately 500-fold. These findings imply that the rate of wild-type LexA cleavage has been optimized during evolution to make the SOS system properly responsive to DNA-damaging treatments. Availability of these mutants will aid in the understanding of rate-limiting steps in intramolecular reactions.

Sacralization of epidural block with repeated doses of 0.25% bupivacaine during labor

A descriptive analysis of the progression of epidural block with repeated doses of 0.25% bupivacaine was performed, assessing pain relief (visual analog scoring), dermatomal spread of sensory and motor block, and the associated management and outcome of labor. The influence of epinephrine 1:200,000 on these observations was also assessed by the random assignment of study patients into two groups, one receiving 10 ml of 0.25% bupivacaine plain (n = 28) and another group receiving 10 ml of 0.25% bupivacaine with commercially added epinephrine 1:200,000 (n = 27). Only primigravid patients were studied. Data comparisons were considered significant at p less than 0.05. With repeated doses of 0.25% bupivacaine, administered within fixed dosing intervals of 60-90 minutes, there was an increasing spread of sensory block toward sacral dermatomes while the upper level of sensory block did not change. Sacral sensory analgesia was present in only 3.5% of patients after the first dose of bupivacaine but was evident in 63.2% of patients following the fourth epidural injection. A similar increase in the number of patients with significant motor weakness was also seen as the number of top-up doses increased. A comparison of patients receiving plain solutions and epinephrine containing bupivacaine showed similar demographic profiles between the groups. Both groups received a similar dose of bupivacaine and experienced comparable management and outcome of labor. Epinephrine in a 1:200,000 concentration did not influence the changing characteristics of the epidural block over time. The duration of labor was not significantly different between groups (10.3 +/- 5.2 hours for the plain group and 11.0 +/- 4.7 hours for the epinephrine group).(ABSTRACT TRUNCATED AT 250 WORDS)

Health, homelessness, and poverty. A study of clinic users

When seeking medical care, homeless persons often turn to health centers that were designed to treat the poor who have homes. To provide for effective medical care, personnel in such facilities need to know how the health care needs of the homeless are different from those of other clinic users. To compare the physical health of these two groups, we conducted a health survey and screening physical examination of 464 patients who attended the general adult and homeless clinic sessions of one of the main neighborhood health centers in Los Angeles County, California. As compared with the poor who have homes, homeless persons were more likely to have dermatological problems (32% vs 21%), functional limitations (median, 2 vs 0 per person), seizures (14% vs 6%), chronic obstructive pulmonary disease (21% vs 12%), social isolation, serious vision problems (22% vs 12%), foot pain, and grossly decayed teeth (median, 1 vs 0 per person). We conclude that to care more optimally for homeless adults, health centers must pay attention to their functional disabilities, substance abuse, skin abnormalities, vision impairment, dental problems, and foot problems.

Use and abuse of imprecision profiles: some pitfalls illustrated by computing and plotting confidence intervals

Published estimates of the imprecision characteristics of immunoassays are often based on quantities of data that seem to be inadequate. The increasing use of imprecision profiles has not necessarily improved the situation. We describe and illustrate a method of computing 95% confidence intervals for profiles estimated directly from replicated assay results. The data used were chosen to mimic the sort of data that are typically available in practice, either within laboratories or from external quality-assessment programs. Use of confidence intervals is an effective pictorial way of incorporating information about the quantity and the distribution of the data used for estimation. This is in keeping with an important property of imprecision profile plots: potentially complex information is summarized in a readily comprehensible way. A computer program is available for estimating and plotting profiles and their 95% confidence intervals.

Use and abuse of imprecision profiles: some pitfalls illustrated by computing and plotting confidence intervals

Published estimates of the imprecision characteristics of immunoassays are often based on quantities of data that seem to be inadequate. The increasing use of imprecision profiles has not necessarily improved the situation. We describe and illustrate a method of computing 95% confidence intervals for profiles estimated directly from replicated assay results. The data used were chosen to mimic the sort of data that are typically available in practice, either within laboratories or from external quality-assessment programs. Use of confidence intervals is an effective pictorial way of incorporating information about the quantity and the distribution of the data used for estimation. This is in keeping with an important property of imprecision profile plots: potentially complex information is summarized in a readily comprehensible way. A computer program is available for estimating and plotting profiles and their 95% confidence intervals.

Effect on a geriatric service of opening a 25-bed ward on the district general hospital site: an audit

Notes and discharge summaries of 2,560 patients were analysed in a pre-planned study to determine how the establishment of a 25-bed assessment ward on the district general hospital (DGH) site affected the work of a geriatric unit that had previously had no DGH beds. Throughput, changes in referrals and practice, and changes in outcome were measured using a computerised programme which examined the work of the unit for a year before and a year after the opening of the assessment ward. There were no changes in overall bed numbers or staffing, so changes were likely to be the direct result of establishing the DGH beds. The second year of the study showed a 33% increased throughput, with increased referrals from the accident and emergency department and evidence of more active investigation and treatment and a tendency towards a shorter length of stay. There was an increased number of transfers from all departments to the geriatric department for rehabilitation and a shortened time interval to transfer. Admissions to the general medical unit for patients aged 65-74 and 75+ did not change.

A computer program for estimating imprecision characteristics of immunoassays

A reliable numerical algorithm is described, together with a computer program written in FORTRAN IV and FORTRAN 77, for estimating a three-parameter variance function by approximate conditional likelihood. The function is sufficiently flexible to provide for a several thousand-fold relative change in variance and appears to be a good model for the severely heteroscedastic results obtained from immunoassays. The computer program is primarily intended for summarizing imprecision characteristics of immunoassays in the form of imprecision profiles, but the estimated variance functions have additional application whenever further parametric analysis of immunoassay results is undertaken (e.g., as a weighting function when immunoassay results are used in a least-squares regression analysis). The flexibility of the function implies useful application in any area where heteroscedasticity is particularly severe.

The conformational flexibility of class I H-2 molecules as revealed by anti-peptide antibodies specific for intracytoplasmic determinants: differential reactivity of beta 2-microglobulin "bound" and "free" H-2Kb heavy chains

Immunoprecipitation experiments using anti-peptide antisera prepared against exon 6, exon 7 and exon 8-encoded intracytoplasmic regions of the H-2Kb gene product indicated that approximately 1/3 of the H-2Kb heavy chains in a cell surface-labelled glycoprotein fraction from EL-4 cells, or H-2b spleen cells, is not associated with beta 2-microglobulin (beta 2-m). This population of "free" H-2Kb heavy chains failed to react with alloantisera or monoclonal antibodies specific for conventional H-2Kb serological determinants, suggesting that significant conformational alterations were induced in the extracellular domains upon dissociation of beta 2-m. In addition, although antibodies to intracytoplasmic peptide 8 were able to react with both "free" and beta 2-m "bound" heavy chains, the determinants seen by anti-peptide 6 and anti-peptide 7 were only recognized in the "free" heavy chain. These data suggest that the conformational perturbation of the extracellular domains induced by beta 2-m dissociation can be "transmitted" to the intracytoplasmic region of the heavy chain. These results indicate the potential for a class I heavy chain-mediated transmembrane signalling event, and suggest that the "free" class I heavy chain might have a role to play in the major histocompatibility complex (MHC)-restricted presentation of T-cell determinants to cytotoxic T-lymphocytes.

Tuberculosis in children and adolescents

The epidemiology, pathogenesis, and clinical picture of primary tuberculosis are presented as they are seen today in the United States in children and adolescents. Diagnosis, treatment, and prevention of the disease are discussed in detail.

A method for direct estimation of imprecision profiles, with reference to immunoassay data

A three-parameter model for directly estimating imprecision profiles from replicated immunoassay results is compared with a six-parameter indirect profile model obtained by the usual method of combining error in the raw response measurements with the slope of the standard curve. Direct estimation is likely to be less reliable when based on the limited data collected from a single assay, and may underestimate variability at high concentrations when many results are clustered at the upper end of the concentration range. However, at concentrations near the assay detection limit (often a region of particular interest), direct estimation is superior to the indirect method if a logistic or related function is used as the standard curve model. Direct estimation of imprecision profiles has useful application whenever the internal details of an assay system are not readily available, for example, in analysis of data collected in external surveys.

A method for direct estimation of imprecision profiles, with reference to immunoassay data

A three-parameter model for directly estimating imprecision profiles from replicated immunoassay results is compared with a six-parameter indirect profile model obtained by the usual method of combining error in the raw response measurements with the slope of the standard curve. Direct estimation is likely to be less reliable when based on the limited data collected from a single assay, and may underestimate variability at high concentrations when many results are clustered at the upper end of the concentration range. However, at concentrations near the assay detection limit (often a region of particular interest), direct estimation is superior to the indirect method if a logistic or related function is used as the standard curve model. Direct estimation of imprecision profiles has useful application whenever the internal details of an assay system are not readily available, for example, in analysis of data collected in external surveys.

Genetic basis of resistance to rimantadine emerging during treatment of influenza virus infection

The emergence of influenza A viruses which had acquired resistance to rimantadine during a clinical trial (C. B. Hall, R. Dolin, C. L. Gala, D. M. Markovitz, Y. Q. Zhang, P. H. Madore, F. A. Disney, W. B. Talpey, J. L. Green, A. B. Francis, and M. E. Pichichero, Pediatrics 80:275-282, 1987) provided the opportunity to determine the genetic basis of this phenomenon. Analysis of reassortant viruses generated with a resistant clinical isolate (H3N2) and the susceptible influenza A/Singapore/57 (H2N2) virus indicated that RNA segment 7 coding for matrix and M2 proteins conferred the resistant phenotype. Resistant viruses isolated from seven patients each contained a single change in the nucleotide sequence coding for the M2 protein which resulted in substitutions in amino acid 30 (two viruses) or 31 (five viruses) in the transmembrane domain of the molecule. These changes occurred in locations identified in influenza viruses selected for resistance to amantadine in tissue culture and indicate a common mechanism of action of the two compounds in cell culture and during chemotherapeutic use.

Genetic variability in white-tailed deer

Genetic variability at 36 loci was studied in white-tailed deer (Odocoileus virginianus) populations, on the Savannah River Plant (SRP) in South Carolina. Mean multilocus heterozygosity (H), percentage of polymorphic loci (P) and average number of alleles per locus (A) for white-tailed deer were calculated and compared with values for white-tailed deer from several locations (SRP deer: H = 9.9 per cent, P0.05 = 30.6 per cent, A = 1.89; white-tailed deer overall: H = 10.4 per cent, P0.05 = 32.3 per cent, A = 1.94). Frequency distributions for single locus heterozygosity values (h) and the number of alleles per locus for white-tailed deer were found to be significantly different from those of mammals in general. Analysis of single-locus data based on quaternary structure and functional groups of proteins failed to demonstrate expected differences as predicted from the literature. White-tailed deer have a high level of heterozygosity, but they do not exhibit many of the life history and environmental characteristics associated with high heterozygosity in other animals.

Outbreak of severe hepatitis due to delta and hepatitis B viruses in parenteral drug abusers and their contacts

We investigated an unusually large and severe outbreak of hepatitis B, primarily involving parenteral drug abusers and their sexual contacts, in Worcester, Massachusetts, over a 21-month period from 1983 to 1985. Of 135 patients with drug-related acute hepatitis B, 81 percent were parenteral drug abusers and 19 percent had sexual contact with drug abusers; 13 fulminant cases resulted in 11 deaths. Among the patients with hepatitis B, evidence of delta virus infection was found in 54 percent of drug abusers, 33 percent of their sexual contacts, and 9 percent of other patients with acute hepatitis B (P less than 0.001). Most of the delta infections (86 percent) were coinfections with hepatitis B virus; the balance were superinfections. Delta infection was strongly associated with fulminant hepatitis: 91 percent of patients with a fulminant outcome had delta infection, as compared with 45 percent of less severely ill drug abusers and their contacts (P = 0.0037). Alcohol, other drugs, and other hepatitis viruses could not be implicated as hepatotoxic cofactors for fulminant disease. This outbreak appeared to result from the concurrent spread of hepatitis B and delta viruses among new drug users. Control measures included the distribution to physicians of guidelines on prophylaxis in contacts of patients with hepatitis B, health education for drug abusers, and a hepatitis B vaccination program. Despite these efforts, the outbreak continued unabated until the number of new cases began to decline slowly in late 1986.