Proposed: an international code of ethics for medical genetics

Wertz DC, Fletcher JC. Proposed: an international code of ethics for medical genetics.
Clin Genet 1993: 44: 37–43. © Munksgaard, 1993     

β-Methyl-15-p-iodophenylpentadecanoic acid metabolism and kinetics in the isolated rat heart

The use of 15-p-iodophenyl--methyl-pentadecanoic acid (Me-IPPA) as an indicator of long chain fatty acid (LCFA) utilization in nuclear medicine studies was evaluated in the isolated, perfused, working rat heart. Time courses of radioctivity (residue curves) were obtained following bolus injections of both Me-IPPA and its straight chain counterpart 15-p-iodophenyl-pentadecanoic acid (IPPA). IPPA kinetics clearly indicated flow independent impairment of fatty acid oxidation caused by the carnitine palmitoyltransferase I inhibitor 2[5(4-chlorophenyl)pentyl]oxirane-2-carboxylate (POCA). In contrast, Me-IPPA kinetics were insenstive to changes in fatty acid oxidation rate and net utilization of long chain fatty acid. Analysis of radiolabeled species in coronary effluent and heart homogenates showed the methylated fatty acid to be readily incorporated into complex lipids but a poor substrate for oxidation. POCA did not significatly alter metabolism of the tracer, suggesting that the tracer is poorly metabolized beyond Me-IPPA-CoA in the oxidative pathway.     

The effects of short-term smokeless tobacco deprivation on performance

Several past studies have reported reliable changes in reaction time performance and self-rated withdrawal scores as a consequence of cigarette deprivation. The purpose of the present study was to determine, prospectively, the effect 24 h of smokeless tobacco deprivation in regular users has on performance and the associated withdrawal symptomology. Forty smokeless tobacco users (Copenhagen brand) were randomly divided evenly into two groups gen brand) were randomly divided evenly into two groups (N=20)24 h of deprivation and no deprivation. A third group of ten nonchewers was added as another control group. The results indicated that behavioral, subjective and physiological changes are associated with smokeless tobacco deprivation in regular users. These include increased craving scores, reaction time, self-rated withdrawal symptoms and decreased heart rate.     

Real-time nested multiplex PCR for the detection of herpes simplex virus types 1 and 2 and varicella zoster virus

One hundred forty-nine specimens were tested in a LightCycler nested multiplex polymerase chain reaction (LCnmPCR) for Herpes simplex virus (HSV)1, HSV2, and VZV. Eighty-one were from genitourinary medicine (GUM) patients and the other 68 specimens were from other patients with skin lesions. The results were compared to a conventional multiplex nested PCR (nmPCR) using agarose gel electrophoresis. Twenty-five specimens were positive in both assays for HSV1 and 29 were positive for VZV. For HSV2 there were 27 positive in the LCnmPCR and 26 positive in the nmPCR assay. The melting temperatures (Tms) of each target were different with a mean of 84.75 degrees C for HSV1, 88.57 degrees C for HSV2, and 83.62 degrees C for VZV. The melting curves of positive specimens directly overlaid the melting curves of the positive controls in the assay. The LCnmPCR assay is a convenient alternative to conventional PCR using agarose gel electrophoresis. It improves specimen turnaround time by eliminating the need for gel electrophoresis, transillumination, and gel photography. It also shows increased sensitivity for HSV2 over our standard assay. This LCnmPCR reduces further the possibility of amplicon contamination with nested PCR protocols.     

Detection of Aspergillus fumigatus by polymerase chain reaction.

Aspergillus fumigatus is an opportunistic nosocomial pathogen causing an often fatal pneumonia, invasive aspergillosis (IA), in immunosuppressed patients. Oligonucleotide primers were used to amplify a 401-bp fragment spanning the 26S/intergenic spacer region of the rDNA complex of A. fumigatus by the polymerase chain reaction (PCR). The primers were highly sensitive and specific: as little as 1 pg of A. fumigatus genomic DNA could be detected, and the primers only amplified DNA from A. fumigatus and not any other fungal, bacterial, viral, or human DNA tested. Using the PCR, we were able to detect A. fumigatus DNA in lung homogenates from immunosuppressed mice experimentally infected with A. fumigatus but not from immunosuppressed uninfected controls. There was 93% correlation between the culture results and the PCR results. In a retrospective clinical study, the sensitivity of the PCR for the detection of A. fumigatus in clinical samples was confirmed by positive amplification in three of three culture-positive respiratory samples from confirmed cases of IA. Because isolation of Aspergillus spp. may reflect contamination and colonization without infection, the feasibility of using the PCR was evaluated by analyzing culture-negative samples from both immunosuppressed patients at high risk for IA and immunocompetent patients with other lung infections. Only 2 of 10 patients were culture negative and PCR positive in the high-risk group, and 2 of 7 patients were culture negative and PCR positive in the immunocompetent group. The results indicate that PCR detection might be a valuable adjunct to current laboratory methods to diagnose IA.     

Glibenclamide treatment in a Cantú syndrome patient with a pathogenic ABCC9 gain‐of‐function variant: Initial experience

Cantú syndrome (CS), characterized by hypertrichosis, distinctive facial features, and complex cardiovascular abnormalities, is caused by pathogenic variants in ABCC9 and KCNJ8 genes. These genes encode gain‐of‐function mutations in the regulatory (SUR2) and pore‐forming (Kir6.1) subunits of K_ATP channels, respectively, suggesting that channel‐blocking sulfonylureas could be a viable therapy. Here we report a neonate with CS, carrying a heterozygous ABCC9 variant (c.3347G>A, p.Arg1116His), born prematurely at 32 weeks gestation. Initial echocardiogram revealed a large patent ductus arteriosus (PDA), and high pulmonary pressures with enlarged right ventricle. He initially received surfactant and continuous positive airway pressure ventilation and was invasively ventilated for 4 weeks, until PDA ligation. After surgery, he still had ongoing bilevel positive airway pressure (BiPAP) requirement, but was subsequently weaned to nocturnal BiPAP. He was treated for pulmonary hypertension with Sildenafil, but failed to make further clinical improvement. A therapeutic glibenclamide trial was commenced in week 11 (initial dose of 0.05 mg^–1 kg^–1 day^–1 in two divided doses). After 1 week of treatment, he began to tolerate time off BiPAP when awake, and edema improved. Glibenclamide was well tolerated, and the dose was slowly increased to 0.15 mg^?1 kg^?1day^?1 over the next 12 weeks. Mild transient hypoglycemia was observed, but there was no cardiovascular dysfunction. Confirmation of therapeutic benefit will require studies of more CS patients but, based on this limited experience, consideration should be given to glibenclamide as CS therapy, although problems associated with prematurity, and complications of hypoglycemia, might limit outcome in critically ill neonates with CS.     

Evaluation of endothelial cell migration with a novel in vitro assay system

In this study we introduce a novel in vitro 'oil-drop' assay system for the measurement of endothelial cell (EC) migration, based on the original concept of the Teflon fence assay (Pratt et al., 1984; Am. J. Pathol. 117: 349–354). An aliquot of 15–20,000 human umbilical vein EC (HUVEC) is pipetted through a layer of mineral oil. The cells readily attach, spread and migrate on the surface of a matrix-coated tissue culture dish as a confluent circular monolayer. Migration is measured as the net increase in the total area covered at 24 hours. We have used this system to quantify EC migration on matrices composed of a mixture of type I collagen and either von Willebrand factor (vWF) or fibronectin (FN) in the presence or absence of tumor necrosis factor (TNF). Plating efficiency on both vWF/collagen and FN/collagen, measured by counting cells after attachment and spreading, is about 80%. With this method, migration on vWF/collagen was about 6.4 mm² and 5.3 mm² for TNF-treated and untreated HUVEC, respectively. HUVEC migration on FN/collagen was slightly greater – 6.4 mm² and 6.5 mm² with and without TNF treatment, respectively. During the 24 hour time period, HUVEC numbers increased 30–40% on vWF/collagen, and 60–80% on FN/collagen, with increased proliferation observed with TNF- treatment. EC proliferation could be completely inhibited by 2 mM hydroxyurea. This assay system has proven useful in our studies to quantify cell migration and proliferation.