'Feeling the pressure': structural insights into a gated mechanosensitive channel

The structure determination of the large-conductance mechanosensitive channel (MscL) from Mycobacterium tuberculosis has revealed the architecture of the first full-length, gated pentameric ion channel. This structure provides insights into the elements participating in the conductance and gating mechanisms of these channels.

Prenatal alcohol consumption. Self versus collateral report

The reservations expressed about the accuracy of patient self-reports of drinking may be heightened when obtaining information about prenatal alcohol consumption, which may be subject to fears of social or medical disapproval. Thus, clinicians may seek collateral reports to confirm patients' reports during this critical time. The purpose of this study is to compare the self and collateral reports of antepartum alcohol consumption by 247 pregnant women, obtained shortly after the initiation of prenatal care, and again after delivery. Collateral reports of subjects were exceeded by the subjects' self-reports of alcohol consumption before pregnancy and in the antepartum.

Biomechanical properties of muscle-tendon unit under high-speed passive stretch

OBJECTIVE

The purpose of this study was to investigate the strain injury mechanisms of the Achilles muscle-tendon unit during high-speed passive stretch.

DESIGN

The high-speed traction device consisted of an impactor which dropped freely to hit one end of a lever, transferring the impact energy to traction energy at the other end. A muscle-tendon unit was attached to the other end of the lever via a force link, and the elongation was recorded with a high-speed camera.

BACKGROUND

The muscle-tendon unit is thought to act viscoelastically. It is generally strain rate dependent, exhibiting higher tensile stress at faster strain rates. However, previous studies of passive stretch in muscle-tendon units usually employed low strain rates.

METHODS

16 fresh Achilles muscle-tendon units were subjected to passive stretch at a test speed of 310 cm s(-1). The history of elongation and the traction force of the muscle-tendon unit during the elongation process were analyzed.

RESULTS

The muscle-tendon units exhibited highly nonlinear mechanical behavior. Most of the elongation occurred in muscle and resulted in structural failure. Failure was not found in the tendon or muscle-tendon junction. Muscle fibers during stretching reached their maximum mechanical strength and then progressively ruptured.

CONCLUSION

The strain rate is an important factor in strain injuries of the muscle-tendon unit due to passive stretch. The muscle is a good energy absorber; the rupture process can absorb a great deal of external energy and prevent complete failure of the muscle, while also protecting bone and joints.

RELEVANCE

The study of muscle-tendon unit under high-speed stretch could help us to understand the mechanism of strain injuries over passive stretch in real-life situations.

Identifying prenatal alcohol use: screening instruments versus clinical predictors

The purpose of this study is to compare the accuracy of screening instruments with clinical predictors in the identification of prenatal alcohol use. 350 women initiating prenatal care at the Brigham and Women's Hospital (Boston, MA) completed the T-ACE, AUDIT, and SMAST. The predictive accuracy of each was compared using Receiver Operating Characteristic (ROC) curve analysis. The T-ACE, AUDIT, and clinical predictors alone correctly identified 65 to 70% of current drinkers, whereas the SMAST alone performed only slightly better than chance. The predictive ability of the T-ACE was further improved with the addition of clinical predictors.

The TWEAK: application in a prenatal setting

OBJECTIVE

The TWEAK is a screening instrument used to identify women who are risk drinkers. Potential limitations of previous studies of the TWEAK in the prenatal setting include indirect administration of the instrument to minority, indigent pregnant women. The purpose of this study is to assess the efficacy of the TWEAK when it is given directly to a sample of pregnant women of different socioeconomic backgrounds.

METHOD

The original TWEAK, with two different tolerance questions, was administered to a sample of 135 pregnant women enrolled in a study of alcohol use during pregnancy at the obstetrics practices of the Brigham and Women's Hospital in Boston, Massachusetts.

RESULTS

The TWEAK, using the first tolerance question (number of drinks before feeling the first effects of alcohol) with the cut point set at more than two drinks, had the best predictive ability for lifetime alcohol diagnoses and risk drinking. The sensitivity of the TWEAK can be increased if the cut point for the first tolerance question is set at two drinks, with some loss of specificity and predictive ability. Medical record assessment was the least sensitive but most specific method of identifying alcohol use by pregnant women.

CONCLUSIONS

The TWEAK has promise as a screening instrument for identifying risk drinking during pregnancy. Future work should include testing in other clinical populations.

[Gene expression of lipopolysaccharide receptor CD14 and tumor necrosis factor-alpha in rats after thermal injury]

OBJECTIVE

To investigate changes in lipopolysaccharide receptor CD14 and tumor necrosis factor-alpha (TNF-alpha) gene expression in vital organs, and their significance in the pathogenesis of systemic inflammation after burns.

METHODS

Wistar rats were subjected to a 35 percent full-thickness scald injury, then sacrificed pre-burn, and postburn 12, 24, 48, 72 hours, respectively. Tissue samples from liver, kidney, lung and intestine were collected to measure CD14 and TNF-alpha mRNA expression. Peritoneal macrophages were harvested by peritoneal lavage to determine CD14 mRNA expression.

RESULTS

CD14 mRNA expression increased markedly after thermal injury, peaking at both 12 and 48 hours. Likewise, CD14 mRNA levels were significantly up-regulated in peritoneal macrophages. Gene expression of TNF-alpha elevated markedly in liver, lungs, and kidneys after acute insults. Positive correlation was found between CD14 mRNA and TNF-alpha mRNA in liver, lung, and kidney tissues.

CONCLUSIONS

Thermal injury per se can markedly up-regulate both CD14 and TNF-alpha gene expression in various organs. Excessive CD14 mRNA expression may enhance synthesis and release of TNF-alpha stimulated by endotoxin translocation, and the interaction between CD14 and TNF-alpha may play an important role in mediating multiple organ damage secondary to major burns.

Heterozygous germline ATM mutations do not contribute to radiation-associated malignancies after Hodgkin's disease

PURPOSE

The successful treatment of Hodgkin's disease has been associated with an increased incidence of secondary malignancies. To investigate whether genetic factors contribute to the development of secondary tumors, we collected family cancer histories and performed mutational analysis of the ataxia-telangiectasia (AT) gene, ATM, in a cohort of Hodgkin's disease survivors with secondary malignancies. ATM was chosen for evaluation because of the increased radiosensitivity of cells derived from AT patients and obligate heterozygotes and the epidemiologic observation that AT carriers are at increased risk for radiation-induced breast cancer.

PATIENTS AND METHODS

Fifty-two patients who developed one or more neoplasms after treatment for Hodgkin's disease participated in this study. Personal and family histories of cancer were obtained through patient interviews and review of medical records. ATM mutational analysis was performed using a yeast-based protein truncation assay.

RESULTS

Seventy-six secondary neoplasms were observed in this cohort of 52 Hodgkin's disease survivors, with 18 patients (35%) developing more than one secondary neoplasm. Positive family histories of cancer were present in 11 (21%) of 52 patients, compared with three (4%) of 68 Hodgkin's disease patients in a comparison cohort who did not develop secondary neoplasms (P =.008; Fisher's exact test). No germline ATM mutations were identified, resulting in an estimated AT carrier frequency in this population of 0% (90% confidence interval, 0% to 4%).

CONCLUSION

Analysis of the number of tumors per individual and the family history of cancer in our cohort suggests that genetic factors may contribute to development of secondary neoplasms in a subset of Hodgkin's disease survivors. Mutational analysis, however, does not support a significant role for heterozygous truncating ATM mutations. Future studies evaluating other genes involved in DNA damage response pathways are warranted.

Structure of the MscL homolog from Mycobacterium tuberculosis: a gated mechanosensitive ion channel

Mechanosensitive ion channels play a critical role in transducing physical stresses at the cell membrane into an electrochemical response. The MscL family of large-conductance mechanosensitive channels is widely distributed among prokaryotes and may participate in the regulation of osmotic pressure changes within the cell. In an effort to better understand the structural basis for the function of these channels, the structure of the MscL homolog from Mycobacterium tuberculosis was determined by x-ray crystallography to 3.5 angstroms resolution. This channel is organized as a homopentamer, with each subunit containing two transmembrane alpha helices and a third cytoplasmic alpha helix. From the extracellular side, a water-filled opening approximately 18 angstroms in diameter leads into a pore lined with hydrophilic residues which narrows at the cytoplasmic side to an occluded hydrophobic apex that may act as the channel gate. This structure may serve as a model for other mechanosensitive channels, as well as the broader class of pentameric ligand-gated ion channels exemplified by the nicotinic acetylcholine receptor.

Debrisoquine hydroxylase (CYP2D6) and prostate cancer

The p450 hepatic microsomal enzyme system metabolizes exogenous drugs and carcinogens. Debrisoquine hydroxylase (CYP2D6), one member of the p450 hemoproteins, has polymorphic expression leading to poor metabolism of debrisoquine and similar compounds in approximately 7% of Caucasians. The genetic locus for this enzyme has been characterized, and the mutations responsible for the slowed metabolism have been identified. Epidemiological studies of the CYP2D6 phenotype suggest an association between the normal or rapid metabolism phenotype and increased risk of lung and bladder cancer. Preliminary data have also suggested an association with prostate cancer (CaP). We used a PCR-based assay to investigate possible associations between the CYP2D6 B allele, the most common genetic mutation responsible for the poor metabolism phenotype, and CaP. Using genomic DNA isolated from peripheral blood, we genetically typed 571 men with CaP and 767 matched controls, all participants in the Physician's Health Study. Relative to men homozygous for the wild-type allele, heterozygotes for the B allele have an odds ratio of 1.19 (95% confidence interval, 0.94-1.51) for CaP, and men homozygous for the B allele have an odds ratio of 1.37 (95% confidence interval, 0.86-2.20). When analyzed as a trend over zero, one, or two copies of the B allele, there emerges a possible association between the B allele and an increased risk of CaP of borderline statistical significance (P = 0.07).

Pregnant women with negative alcohol screens do drink less. A prospective study

The authors examined the antepartum alcohol consumption of 100 women with negative alcohol screens as they initiated prenatal care. Subjects completed a comprehensive assessment of their alcohol use at 15.7 +/- 4.9 weeks gestation and again 2 months after delivery, with 96% follow-up. The majority (87%) were abstinent in the 90-day period before study enrollment, while pregnant. Moreover, 92% drank no alcohol in the interval between study enrollment and delivery. These results are compared with the antepartum alcohol consumption of 250 women with positive alcohol screens. Routine prenatal screening can efficiently identify those at risk for alcohol consumption in the antepartum.

Lipoprotein(a) levels and heart transplantation atherosclerosis

BACKGROUND

Elevated serum lipoprotein(a) [Lp(a)] levels are associated with the development of native coronary atherosclerosis. The association between increased levels of Lp(a) and the development of accelerated cardiac allograft vasculopathy (ACAV) in patients who have undergone orthotopic heart transplantation has not been firmly established.

METHODS AND RESULTS

We studied 74 consecutive heart transplant recipients with at least 1 year survival to determine the relation between Lp(a) and the presence of ACAV. Recipient and donor clinical and laboratory parameters, including mean serum Lp(a) levels, were obtained. ACAV was defined angiographically as > or =30% stenosis in one or more epicardial arteries. ACAV 1 year after heart transplantation was angiographically present in 26 (35%) patients. Mean donor age (36 +/- 13 years [ACAV (+)] vs 28 +/- 10 years, [ACAV (-)]; p = 0.004) and mean serum triglyceride levels 6 months after transplantation (286 +/- 275 mg/dl [ACAV (+)] vs 169 +/- 85 mg/dl [ACAV (-)]; p = 0.025) were univariate predictors of ACAV. No significant difference in mean serum Lp(a) levels was observed (20 +/- 19 mg/dl [ACAV (+)] vs 30 +/- 30 mg/dl [ACAV (-)]; p = NS). Donor age was the single greatest independent predictor of ACAV by multivariate logistic regression (p = 0.02).

CONCLUSIONS

Lp(a) does not appear to be a risk factor for the development of ACAV 1 year after heart transplantation. Further studies are needed to define the influence of serum Lp(a) on the development of cardiovascular disease after orthotopic heart transplantation.

Neuronal molecular mimicry in immune-mediated neurologic disease

Molecular mimicry is implicated in the pathogenesis of autoimmune diseases such as diabetes mellitus, rheumatoid arthritis, and multiple sclerosis (MS). Cellular and antibody-mediated immune responses to shared viral-host antigens have been associated with the development of disease in these patients. Patients infected with human T-lymphotropic virus type I (HTLV-I) develop HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP), an immune-mediated disorder of the central nervous system (CNS) that resembles some forms of MS. Damage to neuronal processes in the CNS of HAM/TSP patients is associated with an activated cellular and antibody-mediated immune response. In this study, IgG isolated from HAM/TSP patients was immunoreactive with uninfected neurons and this reactivity was HTLV-I specific. HAM/TSP IgG stained uninfected neurons in human CNS and cell lines but not nonneuronal cells. Neuronal western blots showed IgG reactivity with a single 33-kd band in all HAM/TSP patients tested. By contrast, no neuron-specific IgG reactivity could be demonstrated from HTLV-I seronegative controls and, more important, from HTLV-I seropositive, neurologically asymptomatic individuals. Both immunocytochemical staining and western blot reactivity were abolished by preincubating HAM/TSP IgG with HTLV-I protein lysate but not by control proteins. Staining of CNS tissue by a monoclonal antibody to HTLV-I tax (an immunodominant HTLV-I antigen) mimicked HAM/TSP IgG immunoreactivity. There was no staining by control antibodies. Absorption of HAM/TSP IgG with recombinant HTLV-I tax protein or preincubation of CNS tissue with the monoclonal antibody to HTLV-I tax abrogated the immunocytochemical and western blot reactivity of HAM/TSP IgG. Furthermore, in situ human IgG localized to neurons in HAM/TSP brain but not in normal brain. These data indicate that HAM/TSP patients develop an antibody response that targets uninfected neurons, yet reactivity is blocked by HTLV-I, suggesting viral-specific autoimmune reactivity to the CNS, the damaged target organ in HAM/TSP.

Exclusive and persistent use of the entry coreceptor CXCR4 by human immunodeficiency virus type 1 from a subject homozygous for CCR5 delta32

Individuals who are homozygous for the 32-bp deletion in the gene coding for the chemokine receptor and major human immunodeficiency virus type 1 (HIV-1) coreceptor CCR5 (CCR5 -/-) lack functional cell surface CCR5 molecules and are relatively resistant to HIV-1 infection. HIV-1 infection in CCR5 -/- individuals, although rare, has been increasingly documented. We now report that the viral quasispecies from one such individual throughout disease is homogenous, T cell line tropic, and phenotypically syncytium inducing (SI); exclusively uses CXCR4; and replicates well in CCR5 -/- primary T cells. The recently discovered coreceptors BOB and Bonzo are not used. Although early and persistent SI variants have been described in longitudinal studies, this is the first demonstration of exclusive and persistent CXCR4 usage. With the caveat that the earliest viruses available from this subject were from approximately 4 years following primary infection, these data suggest that HIV-1 infection can be mediated and persistently maintained by viruses which exclusively utilize CXCR4. The lack of evolution toward the available minor coreceptors in this subject underscores the dominant biological roles of the major coreceptors CCR5 and CXCR4. This and two similar subjects (R. Biti, R. Ffrench, J. Young, B. Bennetts, G. Stewart, and T. Liang, Nat. Med. 3:252-253, 1997; I. Theodoreu, L. Meyer, M. Magierowska, C. Katlama, and C. Rouzioux, Lancet 349:1219-1220, 1997) showed relatively rapid CD4+ T-cell declines despite average or low initial viral RNA load. Since viruses which use CXCR4 exclusively cannot infect macrophages, these data have implications for the relative infection of the T-cell compartment versus the macrophage compartment in vivo and for the development of CCR5-based therapeutics.

Alcohol use and pregnancy: improving identification

OBJECTIVE

To test the effectiveness of a four-item prenatal-alcohol-use, self-administered screening questionnaire that asks about tolerance to alcohol, being annoyed by other's comments about drinking, attempts to cut down, and having a drink first thing in the morning ("eye-opener") (T-ACE) in an ethnically and socioeconomically diverse sample.

METHODS

Two hundred fifty T-ACE-positive and 100 T-ACE-negative women completed a comprehensive assessment of their alcohol use after initiating prenatal care at the Brigham and Women's Hospital in Boston, Massachusetts. This comprehensive assessment, which included the Alcohol Use Disorders Identification Test and the Short Michigan Alcoholism Screening Test as comparisons to the T-ACE, generated three criterion standards: Diagnostic and Statistical Manual of Mental Disorders, Third Ed., Revised (DSM-III-R), lifetime alcohol diagnoses, risk drinking (regularly having more than one fluid ounce of alcohol per drinking day before pregnancy), and current drinking.

RESULTS

T-ACE-positive pregnant women were more likely than T-ACE-negative women to satisfy DSM-III-R criteria for lifetime alcohol diagnoses (40% versus 14%, P < .001) and risk drinking (39% versus 8%, P < .001) and to have current alcohol consumption (43% versus 13%, P < .001). In contrast, obstetric staff members documented only 33 (9%) women as using alcohol at any time, even though nearly all subjects (96%) were asked about drinking upon initiation of prenatal care.

CONCLUSION

The T-ACE was the most sensitive screen for lifetime alcohol diagnoses, risk drinking, and current alcohol consumption. It outperformed obstetric staff assessment of any alcohol use by pregnant women enrolled in the study.

A comparison of related and unrelated marrow donors

OBJECTIVE

The purpose of this investigation is to test whether related bone marrow donors experience more distress from marrow donation than volunteer unrelated donors.

METHOD

Participants in the study were 77 related and unrelated marrow donors who agreed to complete 11 pre- and 8 postdonation self report questionnaires. Related and unrelated donors were recruited from the Bone Marrow Transplant Programs at the Brigham and Women's Hospital and the Massachusetts General Hospital in Boston, MA. Additional unrelated donors were recruited from the American Red Cross-Carolinas and the Heart of America Bone Marrow Donor Registry in Kansas City, MO.

RESULTS

The 41 unrelated and 36 related marrow donors who participated in this prospective study had similar demographic backgrounds and predonation questionnaire results, although related donors endorsed more items on the Beck Depression Inventory, both before and after narrow harvesting. After narrow donation, related donors reported significantly more pain than unrelated donors (p = .0001).

CONCLUSIONS

It is unlikely that intraoperative events alone could account for the increased pain experienced by related donors. Related donors were more likely to experience moderate to severe physical pain after marrow donation than unrelated donors, on the basis of logistic regression analysis (odds ratio = 7.63; 95% confidence interval 2.74, 23.01).

Genomic organization and functional characterization of the chemokine receptor CXCR4, a major entry co-receptor for human immunodeficiency virus type 1

CXCR4 is both a chemokine receptor and entry co-receptor for T-cell line-adapted human immunodeficiency virus type 1. The genomic organization and promoter function for the entire transcription unit of CXCR4 were determined. The gene contains 2 exons of 103 and 1563 base pairs (bp) interrupted by a 2132-bp intron precisely between codons 5 and 6 of the coding sequences. A transcription start site was identified 88 bp upstream of the initiation codon, and a polyadenylate addition site was identified 22 bp 3' to a polyadenylation signal. Transient expression assays defined a minimal promoter at positions -114 to +43 relative to the transcription start site. This region contains a TATA box, a nuclear respiratory factor-1 (NRF-1) site, and two GC boxes. Specific factor binding to the NRF-1 site and GC boxes were demonstrated by gel mobility shifts and DNase I footprinting. Site-directed mutagenesis showed that the NRF-1 site is crucial for promoter activity providing the first evidence for the regulation of a signal transduction gene by NRF-1. Sequences between -691 and -191 repress CXCR4 promoter activity. Further study of these regulatory elements will be important to understanding how CXCR4 functions as both a chemokine receptor and human immunodeficiency virus type 1 entry co-receptor.

Psychological distress among women with recurrent spontaneous abortion

Fifty-seven of 100 women with recurrent abortion completed questionnaires designed to assess demographic and reproductive variables, depression, anxiety, social desirability, self-esteem, locus of control, and marital adjustment. The results indicated that 32% of the women could be classified as depressed. The subjects also reported higher than average levels of acute and chronic anxiety. Fifty-three percent of the subjects reported below average marital adjustment. Post hoc analyses indicated that the women who had a previous elective abortion had higher levels of anxiety, lower marital adjustment, and different attributions regarding their pregnancy losses than the women who had not had an elective abortion. Having a living child was not a protective buffer against psychological distress.

Lac repressor genetic map in real space

Here, we present a graphic display of the phenotypes of more than 4000 single amino acid substitution mutations on the three-dimensional structure of the lac repressor tetramer bound to DNA. The genetic data and the X-ray diffraction studies contribute to define an allosteric mechanism and yield a visual demonstration of the importance of core or buried residues in protein structure.

Women and alcohol abuse in primary care. Identification and intervention

Female problem drinkers are less likely than men to be identified in the primary care setting. The authors studied 24 adult women attending a general, internal medicine clinic to assess the efficiency of self-reports of alcohol consumption when compared with physician identification and other measures and the impact of a brief intervention on alcohol consumption. Despite the high rate of lifetime (79%) and current (67%) alcohol diagnoses, no patient was in alcohol treatment. Physician identification of alcohol problems was least sensitive but most specific, when compared with other measures. Brief intervention, as offered in this study, did not appear to modify alcohol consumption.

Prognostic significance of detection of prostate-specific antigen transcripts in the peripheral blood of patients with metastatic androgen-independent prostatic carcinoma

OBJECTIVES

To evaluate the prognostic significance of reverse transcriptase polymerase chain reaction (RT PCR) detection of prostate-specific antigen (PSA) mRNA in relation to survival in patients with metastatic androgen-independent prostatic carcinoma (AIPC).

METHODS

Peripheral blood from 122 men (64 from Memorial Sloan-Kettering Cancer Center [MSKCC] and 58 from the Dana Farber Cancer Institute [DFCI]) with metastatic (Stage D2) AIPC was analyzed for PSA mRNA using RT PCR. Forty-one controls without prostatic carcinoma were also evaluated.

RESULTS

RT PCR positivity for PSA mRNA was present in 24 of the 64 (38%) patients seen at MSKCC and in 26 of the 58 (45%) patients followed at DFCI. All control individuals were PSA PCR negative. There was a significant correlation between RT PCR positivity and decreased survival in each of the Memorial and Dana Farber population (P = 0.028 and 0.039, respectively). Serum PSA (at time of blood collection for PCR) was not predictive of survival as a continuous variable in the MSKCC [P = 0.31] and the DFCI (P = 0.09) groups. RT PCR for PSA mRNA was found to be independent from and superior to serum PSA in predicting survival in both the MSKCC and DFCI populations (P = 0.048 and P = 0.027, respectively).

CONCLUSIONS

The detection of PSA mRNA in the peripheral blood by RT PCR is a predictor of survival in patients with metastatic AIPC, and PCR is superior to a single serum PSA measurement. Further studies are needed to test the value of this factor in comparison to and coupled with other prognostic parameters.

Substance abuse and bone marrow transplant

The purpose of this retrospective study is to test the hypothesis that lifetime substance abuse has an adverse impact on survival after bone marrow transplant (BMT). This study included 17 of 468 patients admitted to the Bone Marrow Transplant Unit at the Brigham and Women's Hospital in Boston, Massachusetts who were identified to have lifetime substance abuse (SA). Seventeen comparison subjects were selected from the admissions roster if they matched for disease and stage, type of transplant, pretransplant conditioning regimen, and age, but did not have SA. The medical records of all 34 patients were then reviewed by expert substance abuse clinicians for confirmation of SA and course of transplant. Survival time was calculated from the date of BMT admission to the date of last contact. Survival data were analyzed through Kaplan Meier survival curves and log rank tests for association of survival time with lifetime SA, both before and after stratification for history of cigarette smoking and type of transplant. The patients with and without SA were well matched for all clinical factors. Substance abuse or dependence was confirmed in all 17 patients, with alcohol (71%), marijuana (30%), and opiates (30%) identified as the principal substances of abuse. Survival analysis demonstrated reduced survival times for patients with SA, p = .0022. This difference persisted after stratifying for type of transplant and cigarette smoking. Trends in different survival times by type of transplant (p = .054) and by history of cigarette smoking (p = .07) were also identified. Lifetime substance abuse or dependence appears to have an adverse association with survival after bone marrow transplant when other clinical factors are equal.

Comparison of serum and plasma viral RNA measurements in primary and chronic human immunodeficiency virus type 1 infection

We sought to define the relation between serum and plasma HIV-1 viral RNA load in patients with primary and chronic HIV-1 disease. HIV-1 viral load was determined from 116 serum and plasma samples, including 33 matched pairs, from five patients with primary and three patients with chronic HIV disease using the Roche HIV Monitor assay. The mean +/- standard deviations of the serum and plasma viral RNA levels from the 33 matched pairs were 4.372 +/- 0.885 and 4.478 +/- 0.950 log10 (copies/ml), respectively. This -0.106 log difference between serum and plasma viral RNA levels, which equates to 21% of non-log-transformed values, was not statistically significant by the Wilcoxon sign rank test (p = 0.09). The distributions of serum and plasma viral load slopes, calculated from all available viral RNA load data for each patient, were also not statistically different (p = 0.07). The levels of HIV-1 RNA measured in the serum or plasma of HIV-seropositive patients yield equivalent biologic information.

Dynamics of cell-free viral burden in HIV-1-infected patients

Whereas previous cross-sectional studies have shown a 1-2 log increase in cell-free HIV-1 RNA viral burden associated with disease progression, recent longitudinal studies reveal a less dynamic association. We addressed this conundrum in a cohort of 17 rapid and 20 slow progressors. Initial levels of serum viral RNA from the rapid progressors were 1 log unit higher than those from the slow progressors. Serum RNA increased by >0.5 log in 10 of the rapid progressors (increase group), but the remaining seven showed a <0.5 log increase (static group). Patients whose serum RNA increased had lower amounts of serum RNA at study entry but not at follow-up compared with the static group. There was a trend toward lower CD4 counts in the static group at follow-up. These data suggest that the timing of specimen evaluation can influence interpretation of viral RNA dynamics in HIV disease.

The role of viral phenotype and CCR-5 gene defects in HIV-1 transmission and disease progression

Cellular entry of human immunodeficiency virus type 1 (HIV-1) requires binding to both CD4 (ref, 1, 2) and to one of the chemokine receptors recently discovered to act as coreceptors. Viruses that infect T-cell lines to form syncytia (syncytium-inducing, SI) are frequently found in late-stage HIV disease and utilize the chemokine receptor CXCR-4; macrophage-tropic viruses are non-syncytium-inducing (NSI), found throughout disease and utilize CCR-5 (ref. 3-11). We postulated that CCR-5 gene defects might reduce infection risk in seronegative subjects and prolong AIDS-free survival in seropositive subjects with NSI but not SI virus. Homozygous (delta ccr5/delta ccr5) and heterozygous (CCR5/delta ccr5) CCR-5 deletions (delta ccr5) were found in 7 (2.7%) and 51 (19.5%), respectively, of 261 seronegative subjects from the San Francisco Men's Health Study. CCR-5/delta ccr5 genotype was identified in 33 of 172 (19.2%) nonprogressors and 25 of 234 (10.7%) progressors from the seropositive arm of this cohort. The delta ccr5 allele conferred a significant protective effect against HIV-1 infection (P = 0.001) and a survival advantage against disease progression (P = 0.02). Although both progressing and nonprogressing CCR5/delta ccr5 subjects were identified, a distinct survival advantage was shown for those with NSI virus (P < 0.0001). Thus, the protective effect of delta ccr5 against disease progression is lost when the infecting virus uses CXCR-4 as a coreceptor.

A polymorphism of the 5 alpha-reductase gene and its association with prostate cancer: a case-control analysis

Prostate cancer (CaP) is the most commonly diagnosed, nondermatological cancer in the United States. The development and progression of CaP is influenced by androgens. 5 alpha-Reductase, type II, converts testosterone to dihydrotestosterone and is critical to the development of the prostate. A TA dinucleotide repeat polymorphism exists in the 3' untranslated region of the 5 alpha-reductase type II gene. 5 alpha-Reductase alleles with longer TA repeats are more common in African-Americans, the group with the highest incidence of CaP. It has been hypothesized that the longer TA repeat alleles might be associated with increased risk of CaP. We studied this potential association within the Physician's Health Study, a predominantly Caucasian cohort study. Using PCR we identified the TA genotype in 590 men with CaP and 802 age-matched controls. The frequency of each allele in the controls was TA(0), 0.87, TA(9), 0.13, and TA(18), 0.01. Homozygotes for the longer TA alleles, TA(9) and TA(18), were underrepresented among cases with an odds ratio of 0.47 (confidence interval, 0.20-1.12), but this was not statistically significant (P = 0.08, two tailed). Our analysis does not support the prior hypothesis that longer TA alleles confer an increased risk of CaP in a predominantly Caucasian population; in fact, longer TA alleles are more prevalent in men without CaP.

Primary care: detection of women with alcohol use disorders

There are several limitations to our knowledge of alcohol abuse and women. First, the efficacy for women of traditional alcohol screening instruments is unclear since most have been tested and normalized on male populations. The T-ACE and the TWEAK have been tested primarily in specialized populations, limiting their generalizability. Second, the efficacy of brief intervention among women who are moderate to heavy drinkers is also unclear. Reasons for this gap in our knowledge include exclusion of women from research studies, inadequate sample sizes of female subjects, limiting generalizability, and conflicting results from the studies focusing on women and brief interventions in the general medical setting. The barriers to early identification of problem drinking in women and subsequent intervention in the primary care setting may have application to psychiatric practice as well. Women with alcohol dependence are more likely to be seen in other mental health facilities than in alcohol treatment centers. Because of the high rate of comorbidity of alcohol use disorders among individuals with other mental disorders, a careful review of alcohol consumption should be part of every psychiatric evaluation. Psychiatrists therefore might play an important role in early identification of women problem drinkers and be able to intervene, educate, and work collaboratively with primary care providers to reduce the morbidity and mortality of alcohol-abusing women.

Naltrexone, relapse prevention, and supportive therapy with alcoholics: an analysis of patient treatment matching

Alcohol-dependent patients (N = 97) were randomly assigned to receive either naltrexone or placebo and either relapse prevention therapy or supportive therapy. The present report explored the hypothesis that patients could be matched to the above treatments on the basis of specific pretreatment characteristics. Treatment matching variables explored included craving, alcohol dependence severity, and cognitive measures of learning and memory. Results of linear regression analyses tentatively suggest that patients experiencing higher levels of craving and poorer cognitive functioning may derive the greatest benefit from naltrexone versus placebo. For psychotherapy, lower levels of verbal learning were associated with poorer drinking outcomes for relapse prevention therapy but not for supportive therapy. Conversely, higher levels of verbal learning were associated with better outcomes for relapse prevention therapy but not for supportive therapy.

Naltrexone, relapse prevention, and supportive therapy with alcoholics: an analysis of patient treatment matching

Alcohol-dependent patients (N = 97) were randomly assigned to receive either naltrexone or placebo and either relapse prevention therapy or supportive therapy. The present report explored the hypothesis that patients could be matched to the above treatments on the basis of specific pretreatment characteristics. Treatment matching variables explored included craving, alcohol dependence severity, and cognitive measures of learning and memory. Results of linear regression analyses tentatively suggest that patients experiencing higher levels of craving and poorer cognitive functioning may derive the greatest benefit from naltrexone versus placebo. For psychotherapy, lower levels of verbal learning were associated with poorer drinking outcomes for relapse prevention therapy but not for supportive therapy. Conversely, higher levels of verbal learning were associated with better outcomes for relapse prevention therapy but not for supportive therapy.

Does volume of clinical experience affect performance of clinical clerks on surgery exit examinations?

BACKGROUND

Controversy persists over the educational value of student clerkship clinical activities.

METHODS

Students (109) from the class of 1995 recorded their clinical experiences in a logbook during their surgical clerkship at one of four affiliated teaching hospitals. The influence of clinical experience on examination scores and on correlations between prerotation and postrotation examination performance was determined.

RESULTS

Between sites, marked variation in clinical experience was observed but postrotation scores were similar. High-volume experience in emergency admissions and feedback was associated with better objective structured clinical examination (OSCE) performance, but high-volume outpatient clinic experience was associated with less satisfactory OSCE performance. Correlations between prerotation examination performance and the OSCE was increased by feedback on emergency and elective admissions, in a positive and negative direction, respectively.

CONCLUSIONS

These data show that surgical clerks' clinical skills were enhanced by an increased volume of some but not all clinical experiences and that feedback does not necessarily enhance performance. These data suggest that both the volume of clinical experience and the quality of feedback should be carefully monitored by surgical clerkship directors.

Crystal structure of the lactose operon repressor and its complexes with DNA and inducer

The lac operon of Escherichia coli is the paradigm for gene regulation. Its key component is the lac repressor, a product of the lacI gene. The three-dimensional structures of the intact lac repressor, the lac repressor bound to the gratuitous inducer isopropyl-beta-D-1-thiogalactoside (IPTG) and the lac repressor complexed with a 21-base pair symmetric operator DNA have been determined. These three structures show the conformation of the molecule in both the induced and repressed states and provide a framework for understanding a wealth of biochemical and genetic information. The DNA sequence of the lac operon has three lac repressor recognition sites in a stretch of 500 base pairs. The crystallographic structure of the complex with DNA suggests that the tetrameric repressor functions synergistically with catabolite gene activator protein (CAP) and participates in the quaternary formation of repression loops in which one tetrameric repressor interacts simultaneously with two sites on the genomic DNA.

Six-month follow-up of naltrexone and psychotherapy for alcohol dependence

BACKGROUND

The goal of this study was to examine the persistence of naltrexone's effects on drinking outcomes among alcoholics following discontinuation of treatment and to determine whether coping skills therapy improves long-term outcomes compared with supportive therapy.

METHODS

Eighty of 97 alcohol-dependent subjects randomized to receive naltrexone or placebo and either coping skills therapy or supportive therapy for 12 weeks were assessed at a 6-month off-treatment follow-up.

RESULTS

Subjects who received naltrexone were less likely to drink heavily or to meet criteria for alcohol abuse or dependence than subjects who received placebo. The effect of naltrexone therapy on abstinence rates persisted only through the first month of follow-up. Coping skills therapy was associated with decreased levels of drinking among subjects who received placebo. Psychotherapy condition, however, did not predict alcohol diagnosis at follow-up.

CONCLUSIONS

Some but not all of the benefits resulting from short-term naltrexone treatment persist after discontinuation of treatment. The findings suggest that continued treatment with naltrexone may be beneficial for some patients.

Functional characterization of human immunodeficiency virus type 1 nef genes in patients with divergent rates of disease progression

We have studied the sequence and function of the human immunodeficiency virus type 1 (HIV-1) nef genes from nine patients with highly divergent rates of disease progression enrolled in a longitudinal study of HIV disease. Over an average of 7.8 years of follow-up, three patients had net positive changes in CD4+ T-cell counts, three patients had net negative changes in CD4+ T cells but did not develop AIDS, and three patients progressed to AIDS. The nef gene from each of these patients was amplified and cloned, and the sequence of 8 to 10 clones was determined. Only 2 of 88 (2.3%) nef genes recovered from these nine patients were grossly defective. Moreover, there was no relationship between the phylogeny of nef sequences and the corresponding rates of disease progression from these patients. Representative nef genes from all nine patients were tested for their abilities to downregulate cell surface CD4 in a transient-transfection assay. There was no correlation found between the functions of the nef genes from these patients and their corresponding rates of disease progression. We conclude that the nef gene is not a common mediator of the rate of HIV disease progression in natural infection.

Defective accessory genes in a human immunodeficiency virus type 1-infected long-term survivor lacking recoverable virus

We have been studying a patient who acquired human immunodeficiency virus (HIV) infection via a blood transfusion 13 years ago. She has remained asymptomatic since that time. The blood donor and two other recipients have all died of AIDS. Although this patient has shown persistently strong seroreactivity to HIV type 1 (HIV-1) antigens by Western blot (immunoblot), she has been continually HIV culture negative in results from multiple laboratories over the last 6 years and has a very low viral burden. Her CD4+ T-cell count has fluctuated around a mean of 399 cells per microliters, with little change in lymphocyte subset percentages. Strong cellular immune responses to HIV-1 epitopes by this patient have been demonstrated. We now report the results of an intensive molecular genetic analysis of the HIV-1 proviral quasispecies from this patient sampled over 5 years. Long terminal repeat region sequences supported the argument for normal basal and Tat-mediated promoter activities. Sequential sequencing of the nef gene revealed a low frequency (8.3%) of defective genes and a striking lack of sequence evolution. Functional analysis of predominant nef genes by both a cell surface CD4 downregulation and a viral infectivity complementation assay showed wild-type function. In contrast, sequential analysis of an amplicon containing the vif, vpr, vpu, tat1, and rev1 genes revealed the presence of inactivating mutations in 64% of the clones. These data suggest that this patient, initially infected with a virulent swarm of HIV-1, is presently infected with a more-attenuated viral quasispecies as a result of effective host immunity.

[Systemic and local administration of interferon-gamma impairs wound healing]

Interferon-gamma (IFN-gamma), which is a member of cytokine family, has many physiological functions. In this study, we evaluated the effects of IFN-gamma on wound healing in a model of incised wound of rat skin. Twenty Wistar rats were divided into three groups, consisting of IFN-gamma local administration (n = 8), IFN-gamma systemic administration (n = 8) and normal saline control (n = 4). IFN-gamma was administered in doses of 2,000 u/rat, and then daily. Wound areas were measured everyday. At day 10, tissue from wounds was obtained, and it was evaluated for protein amount in granulation tissue and also subjected to morphometric analysis with hemotoxylin and eosin and collagen fibril stain. We found that IFN-gamma impaired wound healing after either systemic or local administration as compared with control, as evidenced by reduction of new collagen fibril deposition and delay of reepidermidalization. On days 7 and 10 after wounding, wound area in normal saline treated rats was much smaller than those in rats treated with IFN-gamma. These results indicated that the impairing effects of IFN-gamma on wound healing must be considered when it is used in clinic.

Cardiac papillary fibroelastoma

Papillary fibroelastomas are rare cardiac tumors, but they are the most common primary tumor of the heart valves. These lesions occur on any of the valves or endothelial surfaces of the heart and may be detected by echocardiography, cardiac catheterization, during open heart operation for other conditions, or at autopsy. Because of their potential for cerebral and coronary embolization, even small papillary fibroelastomas should be excised.

Problem-based learning: its role in undergraduate surgical education

OBJECTIVE

To familiarize the surgeon with problem-based learning (PBL) and to discuss the current and future role of PBL in undergraduate surgical education.

DATA SOURCES

Two meta-analyses comparing the outcome of a PBL curriculum with a traditional curriculum and other studies in the English-language literature.

STUDY SELECTION

Data on the effectiveness of PBL can best be assessed by a meta-analysis in which the conclusions of many studies are reviewed and combined to provide a more comprehensive picture. The studies chosen represent those from the only two recent meta-analyses of the problem that have appeared in reputable journals.

DATA EXTRACTION

Results reported are those obtained using appropriate techniques and published in reputable journals. Information relevant to the major issues in undergraduate surgical training was selected for inclusion.

DATA SYNTHESIS

PBL depends on self-directed learning, triggered by a clinical problem. The students meet in small groups led by a facilitator and discuss carefully designed clinical cases. At the conclusion, the students will have encountered all the information necessary to solve the case and, in so doing, will have gained knowledge that in a conventional curriculum would usually have been disseminated by lecture. There were only small differences between graduates from the two types of curricula. Those from a PBL curriculum had comparable examination results to those from a traditional curriculum on both basic science and clinically based examinations but were happier with their educational experiences.

CONCLUSIONS

Centres that have adopted a PBL approach have found improved student motivation and enjoyment, but there has been no convincing evidence of improved learning. An intelligent combination of both traditional and PBL approaches will likely provide the most effective training for undergraduate surgical clerks.

Screening and monitoring coeliac disease: multicentre trial of a new serum antibody test kit

A multicentre trial was conducted to evaluate a new test for anti-gliadin antibodies (AGA) in serum (Coeliac Screening Kit, CSK, Medical Innovations Limited, Artarmon, NSW, Australia). The test showed excellent reproducibility for both anti-gliadin IgA and IgG detection. The average intraassay coefficient of variation (CV) was 3.0% for IgA and 2.4% for IgG (n = 6), while the average interassay CV was 6.4% for IgA and 4.3% for IgG (n = 3). By defining a positive test as both IgA and IgG elevated, a sensitivity of 93% in untreated coeliacs (n = 75) was observed. The corresponding specificities in healthy adults (n = 130) and healthy children (n = 77) were > 99% and 100% respectively, while in patients with other gastrointestinal disorders (disease controls) the specificity was 94% (n = 129). The test was also useful in monitoring patients, with anti-gliadin IgA and IgG falling for up to a year after commencing a gluten-free diet (GFD) (12 adults). In some patients however, antibody levels did not reach the normal cutpoint after many months on a GFD, which may reflect the patients' poor adherence to their gluten free diet. The test was superior to the Pharmacia anti-gliadin ELISA, and should be useful as an aid to the diagnosis of coeliac disease, as well as in the follow-up of treated patients.

[Clarithromycin in pediatric age. Personal experience]

The authors report their experience on the use of oral suspension of Clarithromycin in respiratory infections in the pediatric age. Thirty-three patients affected by various infectious pathologies of the respiratory tract, treated with oral Clarithromycin at the dosage of 15 mg/kg/day, were studied. The therapeutic outcome was very encouraging, the drug well tolerated and without side effects.

Emergency physicians' ratings of alcoholism treaters

The purpose of this study is to identify treaters whom emergency physicians perceive to offer effective treatment of alcoholism. A random sample of 2,500 emergency physicians received a questionnaire comparing attitudes toward Alcoholics Anonymous (AA) and professional alcoholism treaters. Physician agreement on the efficacy of alcoholism treaters was greatest for AA (87%), moderate for mental health professionals (including psychiatrists and psychologists, 55%) and least for physicians and surgeons (excluding psychiatrists, 23%; chi-square = 1,024, p = .000000005, df = 2). Physician education about other alcoholism treaters may be necessary if all types of treatment are to be considered for the emergency room patient.

Serologic response to standard inactivated influenza vaccine in human immunodeficiency virus-infected children

We compared the serologic response of 46 human immunodeficiency virus (HIV)-infected children and adolescents and 61 age-matched controls to standard trivalent inactivated influenza vaccine (A/Taiwan (H1N1), A/Shanghai (H3N2), B/Yamagata). Children were immunized according to the package insert recommendations before the 1990 to 1991 influenza season. Serum antibody titers to influenza A were determined before and 1 month after each vaccination and compared for study and control subjects. Serologic responses of HIV-infected participants were correlated with absolute CD4 counts and stage of HIV disease. Regardless of age or HIV status, all groups responded with significant increases in antibody to the influenza A strains (range, 2.1-fold to 11.8-fold), with the exception that antibody to H3N2 rose only 1.5-fold (P = 0.058) among HIV-positive subjects > or = 9 years old. Pre- and postimmunization antibody titers were significantly higher for controls than for HIV-positive subjects. There was no correlation between serologic responses and CD4 counts among HIV-infected subjects, but those with Centers for Disease Control and Prevention-defined acquired immunodeficiency syndrome responded significantly less well to vaccine. We conclude that HIV-infected children and adolescents produce significant antibody rises after inactivated influenza A vaccination but that their absolute antibody concentrations are lower than those seen in age-matched controls.

Prevalence of medical illness in patients with anxiety disorders

OBJECTIVE

This investigation examines the prevalence and characteristics of medical illness in 711 patients enrolled in the Harvard/Brown Anxiety Disorders Research Program (HARP), a multi-center, longitudinal study of anxiety disorders.

METHOD

Eligible subjects were those with present or past index anxiety disorders: panic disorder without agoraphobia, panic disorder with agoraphobia, agoraphobia without panic disorder, social phobia, or generalized anxiety disorder. They were assessed by trained raters using structured diagnostic interviews and the Medical History Form II.

RESULTS

Patients with panic disorder and co-morbid major depressive disorder had significantly higher rates of reported medical illness than anxiety disorder patients without depression. When the rates of medical illness for all subjects were compared with those from the Rand Health Insurance Experiment, we found the prevalence of several medical problems to be disproportionately increased.

CONCLUSIONS

Although our results are preliminary, it appears that patients with panic disorder have more reported medical problems than the public at large, in particular, more ulcer disease, angina, and thyroid disease. Somatic complaints in patients with panic disorder, therefore, need to be carefully considered.

HIV-1 proviral genotypes from the peripheral blood mononuclear cells of an infected patient are differentially represented in expressed sequences

The RNA genome of the human immunodeficiency virus type 1 (HIV-1) is established as proviral DNA in infected cells. Only some of these cells may actively produce the array of viral RNAs that support progeny virion production. In vivo expression of a subset of proviral genotypes could influence the experimental characterization of the viral quasispecies. We have explored the relationship between DNA and cDNA genotypes of the envelope gene by the molecular cloning and nucleotide sequencing of these templates from noncultivated peripheral blood mononuclear cells from an HIV-1-infected patient. Eleven proviral DNA and nine cDNA clones representing the V1-V3 region of gp120 were recovered and sequenced. The proviral group was more heterogeneous than the cDNA group by nucleotide sequence changes and V1 length polymorphisms. Deduced amino acid sequences from this data set showed that the two groups were distinct in primary structure, in the position of N-linked glycosylation sites, and in the net charge of the V3 loop. The V1-V2 region discriminated between the groups more strongly than the V3 region. The differential representation of HIV-1 envelope genotypes in the cDNA versus the proviral compartment may have important implications for the pathogenesis of disease and for the design of antiviral therapeutics.

Phospholipid peroxidation deacylation and remodeling in postischemic skeletal muscle

Reperfusion of ischemic skeletal muscle is associated with white blood cell (WBC) sequestration and hydroperoxy-conjugated diene (HCF) formation, a marker of free radical-mediated phospholipid peroxidation. The purpose of this study was to define the kinetics of phospholipid fatty acyl peroxidation, deacylation, and remodeling in postischemic skeletal muscle during prolonged reperfusion in vivo, and to determine whether reperfusion with WBC and plasma-depleted blood would attenuate postischemic phospholipid peroxidation and myocyte necrosis. The isolated, paired, canine gracilis muscle model was used. After 5 h of ischemia, muscles underwent unaltered reperfusion or initial reperfusion with WBC-deficient blood cells resuspended in hydroxyethyl starch, followed by return to normal circulation (modified reperfusion). The concentration of native fatty acids and HCDs of linoleic acid extracted from muscle phospholipids was quantified by gas chromatography and positively identified by mass spectrometry. Ischemia and reperfusion resulted in phospholipid deacylation and a selective increase in phospholipid stearic acid content, but had no effect on total phospholipid phosphorus. Modified reperfusion decreased 1) early HCD formation (54%) and 2) postischemic skeletal muscle necrosis (49%). These data suggest that reperfusion results in phospholipid deacylation and remodeling, and that the initial oxidant stress during reperfusion may be a significant determinant of ultimate muscle necrosis.

Naltrexone and coping skills therapy for alcohol dependence. A controlled study

Ninety-seven alcohol-dependent patients were treated for 12 weeks in a double-blind, placebo-controlled study evaluating naltrexone and two manual guided psychotherapies in the treatment of alcohol dependence. Patients were randomized to receive either naltrexone or placebo and either coping skills/relapse prevention therapy or a supportive therapy designed to support the patient's own efforts at abstinence without teaching specific coping skills. Naltrexone proved superior to placebo in measures of drinking and alcohol-related problems, including abstention rates, number of drinking days, relapse, and severity of alcohol-related problems. Medication interacted with the type of psychotherapy received. The cumulative rate of abstinence was highest for patients treated with naltrexone and supportive therapy. For those patients who initiated drinking, however, patients who received naltrexone and coping skills therapy were the least likely to relapse.