Electrotonic and dye coupling in hippocampal CA1 pyramidal cells in vitro

The presence of electrotonic and dye coupling in region CA1 of the guinea-pig hippocampus was investigated in the in vitro hippocampal slice preparation. No electrotonic coupling potentials were observed in simultaneous recordings from 101 pairs of pyramidal cells. Also, no electrotonically-coupled short latency depolarizations were observed in more than 75 pyramidal cells in response to antidromic activation of the pyramidal cell population, either in normal bathing medium or in medium with lowered Ca²⁺ concentration and added Mn²⁺. When the fluorescent dye Lucifer Yellow was injected into pyramidal cell somas, spread of the dye to other cells (dye coupling) was often observed. Injection of Lucifer Yellow into the dendrites of these neurons resulted in many fewer cases of dye coupling.The failure to find electrophysiological evidence of electrotonic coupling among CA1 pyramidal cells suggests that such coupling is not a functionally important feature of this area of the CNS. The lack of electrophysiological evidence of coupling combined with the observation that the site of Lucifer Yellow injection influences the extent of dye coupling further suggests that at least part of the observed dye coupling may be artifactual. Electrotonic coupling may exist in a small percentage of hippocampal pyramidal cells. However, it is not clear that this small amount of coupling is either necessary or sufficient for the synchronization of neural activity as has been hypothesized to occur during epileptogenesis.     

The Substance Abuse Treatment Workforce of South Africa

The purpose of this paper is to describe characteristics of substance abuse treatment counselors in the Republic of South Africa, including demographics, education, training, and job duties. Counselors recruited from 24 treatment centers completed a survey after signing informed consent. Counselors were primarily female (75%), racially diverse (36.4% White, 30.8% Black, 18.9% Coloured, 12.6% Indian or Asian, and 1.4% Cape Malay), and were 38 years old on average. The majority (62.3%) held at least an equivalent of a bachelor’s degree, and just under half (49%) were registered social workers. Counselors had a mean of 5.3 years’ experience in substance abuse treatment. The substance abuse treatment workforce of South Africa appears to be young and educated, yet only one third of the counselors had any formal training in Cognitive Behavioral Therapy. South African counselors could benefit from more training in evidence-based techniques.     

Treatment of advanced HIV disease in antiretroviral-naïve HIV-1-infected patients receiving once-daily atazanavir/ritonavir or twice-daily lopinavir/ritonavir, each in combination with tenofovir disoproxil fumarate and emtricitabine

Current guidelines for HIV therapy recommend initiating treatment at a CD4 cell count of 500 cells/mm(3). However, a large proportion of patients with HIV infection begin antiretroviral treatment at a more advanced stage. In the CASTLE study, patients with the most advanced HIV disease (CD4 cell count <50 cells/mm(3)) showed that 78% (45/58) vs. 58% (28/48) of the patients achieved HIV RNA <50 copies/mL in the intent-to-treat analysis at week 96 for atazanavir/ritonavir and lopinavir/ritonavir, respectively. This current sub-analysis of the CASTLE study describes demographics, virologic failure, discontinuations, safety, tolerability, immunologic response, and clinical outcomes for the following baseline strata: CD4 cell count (cells/mm(3)) <50, 50 to <100, 100 to <200, and ≥200 and HIV RNA (copies/mL) <100,000, 100,000 to <500,000, and ≥500,000. In the lowest CD4 cell count stratum (<50 cells/mm(3)), the proportion of discontinuations was 2-fold greater for the lopinavir/ritonavir arm (33%) than for the atazanavir/ritonavir arm (16%) with a similar rate of virologic failure between the two groups. Also in this CD4 cell count stratum, grades 2-4 treatment-related adverse events occurred in 25% in the atazanavir/ritonavir group and in 43% of lopinavir/ritonavir group, and the rate was also higher than in the higher CD4 cell count strata within the lopinavir/ritonavir treatment group (range: 29-34%). Grades 2-4 treatment-related diarrhea and nausea occurred in more patients receiving lopinavir/ritonavir than atazanavir/ritonavir in all strata. The atazanavir/ritonavir group had more grades 2-4 treatment-related jaundice than in the lopinavir/ritonavir group. These results highlight the importance of tolerability of antiretroviral therapy (ART) in the patients at greatest risk of morbidity and mortality when using regimens of similar potency.     

Association between pediatric asthma care quality and morbidity and English language proficiency in Ohio

Objective: Limited English proficiency can be a barrier to asthma care and is associated with poor outcomes. This study examines whether pediatric patients in Ohio with limited English proficiency experience lower asthma care quality or higher morbidity. Methods: We used electronic health records for asthma patients aged 2–17 years from a regional, urban, children's hospital in Ohio during 2011–2015. Community-level demographics were included from U.S. Census data. By using chi-square and t-tests, patients with limited English proficiency and bilingual English-speaking patients were compared with English-only patients. Five asthma outcomes—two quality and three morbidity measures—were modeled using generalized estimating equations. Results: The study included 15?352 (84%) English-only patients, 1744 (10%) patients with limited English proficiency, and 1147 (6%) bilingual patients. Pulmonary function testing (quality measure) and multiple exacerbation visits (morbidity measure) did not differ by language group. Compared with English-only patients, bilingual patients had higher odds of ever having an exacerbation visit (morbidity measure) (adjusted odds ratio [aOR], 1.4; 95% confidence interval [CI], 1.2–1.6) but lower odds of admission to intensive care (morbidity measure) (aOR, 0.3; 95% CI, 0.2–0.7), while patients with limited English proficiency did not differ on either factor. Recommended follow-up after exacerbation (quality measure) was higher for limited English proficiency (aOR, 1.8; 95% CI, 1.4–2.3) and bilingual (aOR, 1.6; 95% CI, 1.3–2.1), compared with English-only patients. Conclusions: In this urban, pediatric population with reliable interpreter services, limited English proficiency was not associated with worse asthma care quality or morbidity.     

Biofilm formation in long-term central venous catheters in children with cancer: a randomized controlled open-labelled trial of taurolidine versus heparin

Taurolidine has demonstrated inhibition of biofilm formation in vitro. The aim of this study was to compare the effect of catheter locking with taurolidine vs heparin in biofilm formation in central venous catheters. Forty‐eight children with cancer were randomized to catheter locking by heparin (n = 22) or taurolidine (n = 26), respectively. After removal, catheters were examined by standardized scanning electron microscopy to assess quantitative biofilm formation. Biofilm was present if morphologically typical structures and bacterial cells were identified. Quantitative and semi‐quantitative cultures were also performed. Biofilm was identified in 23 of 26 catheters from the taurolidine group and 21 of 22 catheters from the heparin group. A positive culture was made of six of the catheters locked with taurolidine and heparin, respectively (p = 0.78). The rate of catheter‐related bloodstream infections (CRBSI) was 0.1 per 1000 catheter‐days using taurolidine and 0.9 per 1000 catheter‐days using heparin (p = 0.03). This randomized trial confirmed that the use of taurolidine as catheter‐lock compared with heparin reduced the rate of CRBSIs; this reduction was not related to a reduction in the intraluminal biofilm formation and the rate of bacterial colonization detected by scanning electron microscopy in the two groups.     

Clinical significance of hyperbilirubinemia among HIV-1-infected patients treated with atazanavir/ritonavir through 96 weeks in the CASTLE study

CASTLE was a randomized 96-week study that demonstrated that atazanavir/ritonavir (ATV/r) was noninferior to lopinavir/ritonavir (LPV/r) in treatment-na?ve HIV-infected patients. Analyses were carried out among patients who received ATV/r in the CASTLE study to better understand the clinical significance of unconjugated hyperbilirubinemia associated with administration of boosted ATV. Hyperbilirubinemia was defined as total bilirubin (conjugated and unconjugated) elevation greater than 2.5 times the upper limit of normal (grade 3-4). Patients in the ATV/r arm were assessed based on the presence or absence of hyperbilirubinemia through week 96. Analyses included number of confirmed virologic responders (CVR; HIV RNA<50 copies per milliliter), impact of hyperbilirubinemia on symptoms, elevations in liver enzymes, patient quality of life, and medication adherence. Through 96 weeks in the CASTLE study, 44% of patients who received ATV/r had hyperbilirubinemia at any time point, and between 12.5% and 21.6% had hyperbilirubinemia at any single study visit. At 96 weeks, 74% of patients overall and 84% and 69% of patients with and without hyperbilirubinemia, respectively, achieved CVR. Symptoms of jaundice or scleral icterus occurred in 5% of patients overall and in 11% with hyperbilirubinemia and 0% without hyperbilirubinemia. Four percent of patients with and 3% of patients without hyperbilirubinemia had grade 3-4 elevations in liver transaminases. Less than 1% of patients discontinued treatment due to hyperbilirubinemia. There were no differences in quality of life or adherence between patients with or without hyperbilirubinemia. In the CASTLE study, hyperbilirubinemia observed in the ATV/r group did not negatively impact clinical outcomes in HIV-infected patients.     

ClC-2 chloride secretion mediates prostaglandin-induced recovery of barrier function in ischemia-injured porcine ileum

BACKGROUND & AIMS: Ischemia results in the breakdown of the intestinal barrier, predisposing patients to sepsis and multiple organ failure. Prostaglandins play a critical role in mediating recovery of barrier function in ischemia-injured intestine through a mechanism involving stimulation of Cl - secretion. In the present study, we investigated the contributory role of individual Cl - channels in the recovery of barrier function in ischemia-injured porcine ileum. METHODS: Ischemia-injured porcine ileal mucosa was mounted in Ussing chambers. Short-circuit current (Isc) and transepithelial resistance (TER) were measured in response to prostaglandin E 2 (PGE 2 ) and pharmacologic inhibitors of epithelial Cl - channels. Immunoassays were used to assess the expression and localization of ion channels. RESULTS: Application of PGE 2 to ischemia-injured ileal mucosa stimulated increases in Isc, an indicator of Cl - secretion, that was followed by marked increases in TER, an indicator of barrier function recovery. In vitro studies revealed that although PGE 2 induced Cl - secretion via at least 3 distinct secretory pathways, recovery of barrier function was initiated by Cl - secretion via ClC-2 Cl - channels co-expressed with occludin and localized to tight junctions within restituting epithelium. Intravenous administration of furosemide to pigs subjected to 1 hour of ileal ischemia impaired recovery of barrier function, as evidenced by decreased TER and increased mucosal-to-serosal 3 H-mannitol flux after a 2-hour reperfusion/recovery period, confirming an important role for Cl - secretory pathways in vivo. CONCLUSIONS: ClC-2-mediated intestinal Cl - secretion restores TER in ischemia-injured intestine. These data may provide the basis for targeted pharmacologic therapy for diseases associated with impaired barrier function.     

Small-Bowel Tumors

Background: The rarity, delayed presentation, and diagnostic difficulty of small-bowel tumors prompted this study.

Study Design: Charts were reviewed retrospectively for 85 patients with 89 small-bowel tumors (22 primary malignant, 23 primary benign, and 44 metastatic) over a 10-year period (1986–1996) at Louisiana State University Medical Center–Shreveport and two affiliated hospitals in Shreveport.

Results: Of the primary malignant tumors, 10 carcinoids and 11 duodenal adenocarcinomas were identified. Most primary benign tumors were adenomatous or hyperplastic polyps, diagnosed by esophagogastroduodenoscopy. Metastatic tumors accounted for nearly 50% of all small-bowel tumors. Across all three tumor types, the most common presenting signs and symptoms were abdominal pain and nausea and vomiting. In addition, patients with benign tumors were more commonly presented with gastrointestinal hemorrhage, and those with metastatic tumors were more likely to present with obstruction. The mean interval from the onset of signs and symptoms to operation was 54 days for primary malignant tumors and 330 days for primary benign tumors. Esophagogastroduodenoscopy and computed tomography of the abdomen were occasionally helpful in diagnosis. Among the 22 primary malignant tumors, curative resections were performed in 11 patients (for 9 carcinoids and 2 adenocarcinomas) and palliative resections were performed in 10 patients (for 9 adenocarcinomas and 1 myxoliposarcoma). One patient had carcinomatosis from colon cancer and an incidentally discovered ileal carcinoid; this carcinoid was not included in this group of resections for primary malignant small-bowel tumors. All operations for 39 (of 44) patients with metastatic tumors were palliative. The remaining 5 (of 44) patients had metastatic duodenal cancer (confirmed by esophagogastroduodenoscopy or endoscopic retrograde cholangiopancreatography with biopsy) and did not undergo laparotomy. Surgical complications occurred more commonly with metastatic than with primary malignant tumors. Patients with primary malignant tumors had a 5-year survival rate of 36%.

Conclusions: These findings demonstrate that small-bowel tumors are difficult to diagnose because of delayed presentation, nonspecific signs and symptoms, and lack of accurate diagnostic studies. If the overall survival of patients with small-bowel tumors is to be improved, clinicians must have a high index of suspicion and be willing to perform exploratory celiotomy early.     

Quasi-normal cornified cell envelopes in loricrin knockout mice imply the existence of a loricrin backup system

The cornified cell envelope, a lipoprotein layer that assembles at the surface of terminally differentiated keratinocytes, is a resilient structure on account of covalent crosslinking of its constituent proteins, principally loricrin, which accounts for up to 60%-80% of total protein. Despite the importance of the cell envelope as a protective barrier, knocking out the loricrin gene in mice results in only mild syndromes. We have investigated the epidermis and forestomach epithelium of these mice by electron microscopy. In both tissues, corneocytes have normal-looking cell envelopes, despite the absence of loricrin, which was confirmed by immunolabeling, and the absence of the distinctive loricrin-containing keratohyalin granules (L-granules). Isolated cell envelopes were normal in thickness (approximately 15 nm) and mass per unit area (approximately 7.3 kDa per nm2); however, metal shadowing revealed an altered substructure on their cytoplasmic surface. Their amino acid compositions indicate altered protein compositions. Analysis of these data implies that the epidermal cell envelopes have elevated levels of the small proline-rich proteins, and cell envelopes of both kinds contain other protein(s) that, like loricrin, are rich in glycine and serine. These observations imply that, in the absence of loricrin, the mechanisms that govern cell envelope assembly function normally but employ different building-blocks.