Comparison of the positive inotropic effects of serotonin,histamine, angiotensin II,endothelin and isoprenaline in the isolated human right atrium

Summary The receptor systems through which serotonin (5-HT), histamine, angiotensin II and endothelin increase the force of contraction were studied in isolated right atria from patients without apparent heart failure.All agonists increased the atrial force of contraction in a concentration-dependent manner; maximal effects, however, were significantly less than those evoked by isoprenaline or Ca²⁺. 5-HT and histamine, but not angiotensin II and endothelin, activated adenylate cyclase, whereas endothelin and angiotensin II stimulated inositol phosphate generation. Experiments with subtype-selective antagonists revealed that histamine effects were mediated by H₂-receptors (sensitive to ranitidine), 5-HT-effects by 5-HT₄-receptors (sensitive to SDZ 205-557) and angiotensin II effects by AT₁-receptors (sensitive to losartan).We conclude that in human right atria the force of contraction can be increased by cyclic AMP-dependent (histamine, 5-HT) and -independent (angiotensin II, endothelin) pathways. Compared to -adrenoceptors, however, all other receptor systems increase the force of contraction only submaximally indicating that the -adrenoceptor pathway is the most important physiological mechanism to regulate force of contraction and/or heart rate in the human heart.Correspondence to O. E. Brodde at the above address     

Anti-SARS-CoV-2 activity of targeted kinase inhibitors: Repurposing clinically available drugs for COVID-19 therapy

Coronavirus disease 2019 (COVID-19) remains a major public health concern, and vaccine unavailability, hesitancy, or failure underscore the need for discovery of efficacious antiviral drug therapies. Numerous approved drugs target protein kinases associated with viral life cycle and symptoms of infection. Repurposing of kinase inhibitors is appealing as they have been vetted for safety and are more accessible for COVID-19 treatment. However, an understanding of drug mechanism is needed to improve our understanding of the factors involved in pathogenesis. We tested the in vitro activity of three kinase inhibitors against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), including inhibitors of AXL kinase, a host cell factor that contributes to successful SARS-CoV-2 infection. Using multiple cell-based assays and approaches, gilteritinib, nintedanib, and imatinib were thoroughly evaluated for activity against SARS-CoV-2 variants. Each drug exhibited antiviral activity, but with stark differences in potency, suggesting differences in host dependency for kinase targets. Importantly, for gilteritinib, the amount of compound needed to achieve 90% infection inhibition, at least in part involving blockade of spike protein-mediated viral entry and at concentrations not inducing phospholipidosis (PLD), approached a clinically achievable concentration. Knockout of AXL, a target of gilteritinib and nintedanib, impaired SARS-CoV-2 variant infectivity, supporting a role for AXL in SARS-CoV-2 infection and supporting further investigation of drug-mediated AXL inhibition as a COVID-19 treatment. This study supports further evaluation of AXL-targeting kinase inhibitors as potential antiviral agents and treatments for COVID-19. Additional mechanistic studies are needed to determine underlying differences in virus response.     

Flow cytometry: Potential utility in monitoring drug effects in breast cancer

Summary Flow cytometric analysis of DNA ploidy and S-phase fraction are well recognized prognostic indicators in breast cancer. The present paper deals with the widening of the applications of flow cytometry to monitoring the effectiveness of antiestrogen therapy, detecting clonal selection and emergence of drug resistance, and monitoring chemosensitizing properties of drugs. Antiestrogen activity can be studied by DNA flow cytometry to address clinical research problems such as patient-specific pharmacokinetics, dosing compliance, and acquired antiestrogen resistance. Patient plasma specimens containing various concentrations of triphenylethylenes can be monitored for drug-induced effects using cell cycle measurements and correlated toin vivo drug levels. DNA flow cytometry has also been instrumental in the study of the effects of prolonged low-dose (0.5 µM for > 100 days) tamoxifen treatment on human estrogen receptor negative MDA-MB-231 cells, where it was shown that tamoxifen may significantly alter cell cycle kinetics and tumorigenicity of these cells, selecting a new, more aggressive, and rapidly growing clone. Lastly, it has been shown that the chemosensitizing properties of another triphenylethylene antiestrogen, toremifene, on estrogen receptor negative, multidrug resistant MDA-MB-231-A1 human breast cancer cells can be studied using flow cytometric analysis. Toremifene (and its metabolites N-desmethyltoremifene and toremifene IV) are able to resensitize MDA-MB-231-A1 cells to vinblastine and doxorubicin, as reflected in a marked shift of cells to G₂/M phase of the cell cycle. Flow cytometry is a widely available technique that might be applied clinically to monitor, at the cellular level, drug effects on tumors, including the modulators of drug resistance.     

Serotonergic mechanisms of cocaine effects in humans

The objective of this study was to investigate the role of serotonin (5-HT) in mediating the effects of cocaine in humans. To accomplish this, 12 subjects each participated in two randomized, double-blind test sessions separated by 1 week. In one session, subjects underwent acute depletion of the 5-HT amino acid precursor tryptophan (TRP), followed by a test dose of intranasal cocaine. In the other session, the cocaine test dose was preceded by sham depletion. Subject ratings of cocaine high were significantly lower following active TRP depletion than after the sham procedure. Subjects also showed an earlier but less sustained rise in self-rated nervousness during active TRP depletion. These findings are consistent with the hypothesis that 5-HT may be involved in mediating the euphorigenic and modulating the anxiogenic effects of cocaine in humans, either directly or through actions on other (e.g., dopaminergic) systems.     

Service utilization among homeless and runaway youth in Los Angeles, California: rates and reasons

Purpose: To describe the service utilization patterns of homeless and runaway youth in a “service-rich” area of Los Angeles, California; identify demographic and other correlates of utilization; and contextualize the findings with qualitative data.

Method: During Phase 1 of this study, survey data were collected from an ethnically diverse sample of 296 youth aged 13–23 years, recruited from both service and natural “hang-out” sites using systematic sampling methods. During Phase 2, qualitative data were collected from 46 youth of varying ethnicities and lengths of time homeless.

Results: Drop-in centers and shelters were the most commonly used services (reported by 78% and 40%, respectively). Other services were used less frequently [e.g., medical services (28%), substance abuse treatment (10%) and mental health services (9%)]. Utilization rates differed by ethnicity, length of time in Los Angeles, and city of first homeless episode (Los Angeles versus all others). Shelter use was strongly associated with use of all other services. Despite youths’ generally positive reactions to services, barriers were described including rules perceived to be restrictive, and concerns youth had about confidentiality and mandated reporting. Youth suggested improvements including more targeted services, more long-term services, revised age restrictions, and more and/or better job training and transitional services to get them off the streets.

Conclusions: Because shelters and drop-in centers act as gateways to other services and offer intervention potential for these hard-to-reach youth, it is vital that we understand the perceived barriers to service utilization.     

Cervical secretory immunoglobulin A in adolescent girls.

PURPOSE: To determine whether there are differences in levels of cervical secretory immunoglobulin A (sIgA) between adolescent girls in the secretory and proliferative phases of their menstrual cycle. METHODS: Sexually active adolescent girls (n = 117) at health maintenance organization (HMO) based adolescent medical clinic were recruited into the study. In addition to demographic and clinical data, cervical specimens were collected for sIgA measurement and gonorrhea culture, urine for chlamydia ligase chain reaction, and blood for progesterone levels. Subjects were classified as being in the proliferative phase or secretory phase of the menstrual cycle on the basis of their progesterone levels. RESULTS: The mean age of the subjects was 17.2 years old. There was no difference in the sIgA levels between those in the proliferative phase of their cycle (n = 45; mean sIgA level, 0.0055 mg/mL) and those in the secretory phase (n = 40; mean sIgA level, 0.0032 mg/mL) (p > .10). CONCLUSIONS: The secretory phase of the menstrual cycle does not appear to be associated with higher levels of sIgA in adolescent girls. These results suggest that adolescents with anovulatory cycles, i.e., those who lack a secretory phase, may not be at increased risk for genital tract infections such as chlamydia or gonorrhea.     

Secondary mania in patients with HIV infection: are antiretrovirals protective?

A case-control study of 19 patients with HIV-associated mania and 57 HIV-seropositive control patients matched by CD4 cell count, age, and year of treatment was undertaken to investigate associations with risk factors for human immunodeficiency virus (HIV) infection, treatment, and disease. There was no significant difference between groups for HIV exposure category, baseline health status, or drugs other than antiretrovirals. Zidovudine therapy provided a significant protective effect against the development of mania, whether administered at or prior to diagnosis of mania. In a 3-year follow-up study, incident AIDS dementia was significantly more common in patients with mania, despite no apparent difference in survival between cases and controls. These findings strengthen the evidence of an etiological association of HIV neuropathology with AIDS mania by demonstrating a protective effect of an antiretroviral agent able to penetrate the central nervous system.     

Measurement of in vitro cellular pharmacokinetics of 5-fluorouracil in human and rat cancer cell lines and rat hepatocytes using a flow-through system

Summary A flow-throught system was used to study the cellular pharmacokinetics of 5-fluorouracil (5-FU) in four human cell lines (squamous-cell carcinoma HEp-2, colon carcinoma WiDr, hepatoma Hep G2, and breast carcinoma MCF-7) as well as in the rat hepatoma H35 cell line and in freshly isolated rat hepatocytes. The system made it possible to restrict the decrease in the concentration of 5-FU in the medium, to keep the volume in which the metabolites accumulated relatively small, and to study the dynamics of a response during and after a change in the composition of the eluent. Clearance of 5-FU from the eluent was achieved predominantly (>95%) by its catabolism to dihydrofluorouracil in the tumor cell lines and to 2-fluoro--alanine in the hepatocytes. Not only rat hepatocytes but also HEp-2 cells showed relatively high clearance values. A concentration-dependent 5-FU elimination was observed, indicating saturation of 5-FU elimination according to Michaelis-Menten kinetics (K_m 14–22 M). The maximal velocity (V_max) values ranged from 0.025 to 0.13 nmol 5-FU/10⁶ cells per minute. For HEp-2 cells, high-concentration pulse injections of 5-FU, thymine, uridine, or uracil immediately led to a reduction in 5-FU conversion, followed by recovery within 5 min. The flow-through system proved to be adequate for the study of the non-linear pharmacokinetics of 5-FU in different intact cells and for the comparison of various manipulations of these pharmacokinetics.Abbreviations 5-FU 5-fluorouracil - FUR 5-fluorouridine - F-DHU dihydrofluorouracil - F--ala 2-fluoro--alanine - F-UPA -fluoroureidopropionic acid - HEPES 4-(2-hydroethyl)-1-piperazine-ethane sulfonic acid - MEM modified minimal essential medium - HBSS Hanks' balanced salt solution - HPLC high-performance liquid chromatography Supported by grant IKA 87-16 from the Netherlands Cancer Foundation. One author (G. J. P.) is the recipient of a senior research fellowship from the Royal Netherlands Academy of Arts and Sciences (KNAW)     

Perinatal support programs: A strategy for the primary prevention of child abuse

Perinatal support programs are offering new hope for the prevention of child abuse. This article reviews the research stimulating these programs, details the prescribed components of perinatal programs according to the Interprofessional Task Force on Health Care of Women and Children and the National Committee for Prevention of Child Abuse, and discusses four demonstration projects currently being conducted.Ellen B. Gray is Program Associate for Primary Prevention and Director of the project, Collaborative Research and Community and Minority Group Action to Prevent Child Abuse, at the National Committee for Prevention of Child Abuse. Reprint requests may be addressed to the author at the National Committee for Prevention of Child Abuse, 332 South Michigan Avenue, #1250, Chicago, Illinois 60604.     

Angiographic Embolization for Intraperitoneal and Retroperitoneal Injuries

Angiographic embolization (AE) has been used extensively for bleeding control after injuries to the face and neck. Its role in abdominal trauma requires further exploration. We reviewed the medical records of 137 consecutive patients who underwent angiography with the intent to embolize bleeding sites within the abdomen. Of them, 97 (71%) had blunt and 40 (29%) had penetrating trauma. AE was performed for hemorrhage associated with pelvic fractures (97 patients), liver lacerations (n= 26), renal lacerations (n= 12), splenic lacerations (n= 5), other injuries (n= 9), and multiple injuries (n= 12). On angiography, 102 patients were found to have bleeding sites and underwent AE, with angiographic and clinical bleeding control in 93 (91%). The rate of successful hemostasis by AE was identical in blunt and penetrating trauma patients. There was no major morbidity after AE. No factors predicted patients with a high likelihood to have a positive angiogram. Patients who had AE before or after a period of attempted hemodynamic stabilization in the intensive care unit were no different with respect to hemodynamic parameters immediately before AE or effectiveness of AE for bleeding control. AE is a safe and effective method for controlling bleeding after blunt and penetrating intra- and retroperitoneal injuries. Early AE may be used in selected patients as a front-line therapeutic intervention that offers expeditious hemostasis and prevents delays in definitive bleeding control.