Construction, calibration, and validation of a simple patch-clamp amplifier for physiology education.

A modular patch-clamp amplifier was constructed based on the Strickholm design, which was initially published in 1995. Various parts of the amplifier such as the power supply, input circuit, headstage, feedback circuit, output and nulling circuits were redesigned to use recent software advances and fabricated using the common lithographic printed circuit board fabrication process and commercially available electronic components. The calibration, validation, and regular recording procedures along with the results of an actual recording of inward Ca(2+) currents from PC12 neuronal cells are described in detail. This work describes the construction of a low-cost patch-clamp amplifier and setting up an electrophysiology recording system in a laboratory with regular technical expertise. The constructed amplifier provides an inexpensive yet practical tool for research and teaching purposes while the experience obtained during construction and setting up of the patch-clamp amplifier provides the basic and advanced understanding required for operating an advanced cell potential recording apparatus.

Synthesis and antagonistic activity of four new 2-alkyl-N-biphenyl fused imidazoles on angiotensin II receptors.

In the current study, four new 2-alkyl-N-biphenyl fused imidazoles were synthesized and the pharmacological properties of these compounds as angiotensin II antagonists were studied. First, the potency of the synthesized compounds on guinea-pig ileum was evaluated and the vasopressor effect of the most potent compound 6a was compared with losartan on isolated perfused rat kidney. The antagonistic activity of compound 6a (sodium 2-propyl-5-carbomethoxy-1-[(biphenyl-4-yl)methyl]pyrrolo[3,2-d]imidazole-2'-carboxylate) on angiotensin II receptors was greater than the other synthesized compounds and in isolated perfused rat kidney was similar to losartan.

Positive bacterial culture of semen from infertile men with asymptomatic leukocytospermia.

OBJECTIVE: To examine results of semen culture in a population of infertile men with asymptomatic leukocytospermia, and to determine the correlation between culture results and sperm characteristics in these patients. METHODS: Semen samples were collected from a group of infertile men (n = 80) after 2-3 days of sexual abstinence. Standard semen analysis was performed according to World Health Organization (WHO) guidelines. Seminal leukocyte concentrations were determined by a myeloperoxidase staining technique. Culture of semen was performed on enriched and specific culture media. RESULTS: Based on the results of semen culture, the samples were classified into three groups: group 1 (enteric gram-negative bacilli [Enterobacteriaceae], n = 13), group 2 (bacteria other than Enterobacteriaceae, n = 15), and group 3 (negative cultures, n = 52). No correlation was found between positive semen culture and sperm characteristics (concentration, motility, and morphology). However, seminal leukocyte concentrations were negatively correlated with percentages of motile sperm and normal sperm morphology. CONCLUSION: Our data indicate that semen samples from infertile men with asymptomatic leukocytospermia may have bacterial contamination, evidenced by positive bacterial cultures. Lack of correlation between positive semen cultures and sperm characteristics may be indicative of early or mild (subclinical) infection.