Hormone responsiveness of cultured Sertoli cells obtained from adult rats after their rapid isolation under less harsh conditions.

During adulthood, testicular Sertoli cells (Sc) coordinate all stages of germ cell (Gc) development involved in sperm production. However, our understanding about the functions of adult Sc is limited because of the difficulties involved in the process of isolating these cells from the adult testis, mainly because of the presence of large number of advanced Gc which interfere with Sc isolation at this age. Most of our knowledge about Sc function are derived from studies which used pre-pubertal rat Sc (18 ± 2-day old) as it is easy to isolate and culture Sc at this age. To this end, we established a less time consuming and less harsh procedure of isolating Sc from adult (60 days of age) rat testis for facilitating research on Sc-mediated regulation of spermatogenesis during adulthood. The cells were isolated using collagenase digestion at higher temperature, reducing the exposure time of cells to the enzyme. Step-wise digestion with intermittent removal of small clusters of tissue helped in increasing the yield of Sc. Isolated Sc were cultured and treated with FSH and testosterone (T) to evaluate their hormone responsiveness in terms of lactate, E2 , cAMP production. Adult Sc were found to be active and produced high amounts of lactate in a FSH-independent manner. FSH-mediated augmentation of cAMP and E2 production by adult Sc was less as compared with that by pre-pubertal Sc obtained from 18-day-old rats. Androgen-binding ability of adult Sc was significantly higher than pre-pubertal Sc. Although T treatment remarkably augmented expression of Claudin 11, it failed to augment lactate production by adult Sc. This efficient and rapid procedure for isolation and culture of functionally viable adult rat Sertoli cells may pave the way for determining their role in regulation and maintenance of spermatogenesis.

Examination of writings concealed by black pressure sensitive adhesive tape.

Examination of concealed writing is often a challenge for forensic document examiners. Although the published literature describes many techniques, these are often only successful when the writing has been concealed by pencil, pen, or by spreading inks of different tint or by smearing of the writing with colored fluids. When black pressure sensitive adhesive (PSA) tape is used, these procedures are ineffective. The present report describes the use of a straight chain hydrocarbon to remove the PSA tape and allow a comparison of the concealed writing with that of a suspect. The use of the solvent had no observable effect on either the writing or the substrate. The procedure is rapid and easy to use and is also effective with other colored PSA tapes.

Climatology of diurnal trends and vertical distribution of ozone in the atmospheric boundary layer in urban North Carolina.

Vertical measurements of ozone were made on a 610-m-tall tower located about 15 km southeast of Raleigh, NC, as part of an effort by the state of North Carolina to develop a state implementation plan (SIP) for ozone control in the Raleigh Metropolitan Statistical Area. During summer 1993, 1994, and 1995, ozone was monitored at ground level, 250 m, and 433 m. Boundary layer wind, temperature, and other meteorological variable profiles were determined from balloon soundings. During summer 1996 and 1997, ozone was monitored at ground level, 76 m, 128 m, and 433 m. This paper presents the analysis and discussion of the five-year data. The evolutions of the convective boundary layer during daytime and the stable nocturnal boundary layer (NBL) were found to have marked impacts on ozone concentrations. A strong diurnal pattern, with an afternoon maximum and an early morning minimum, was dominant at ground level, but it was much weaker at elevated levels and insignificant above the NBL at night. Ozone deposition velocities at night during the measurement periods were estimated to range from 0.09 to 0.64 cm/sec. We found evidence of regional transport of ozone and/or its precursors from northwest and north of the site, which may play a role in high ozone events in the Raleigh-Durham area. Ozone concentrations between the various elevated levels were well correlated, while correlations between the ground and upper levels were much weaker. However, a strong correlation was found between the nighttime and early morning ozone concentrations (CR) in the residual layer above the NBL and the maximum ground level concentration (Co max) the following afternoon. Based on this correlation, the latter may be predicted by an observational model Co max = 27.76e 0.016 CR.

Ozone in the urban southeastern United States.

Ozone measurements (daily maximum values) from the Aerometric Information Retrieval System database are analyzed for selected sites, during 1980 to 1988, in southeastern USA. Frequency distributions, for most sites during most years, show a typical bell-shaped curve with the higher frequency around the yearly daily maximum ozone mean of about 100 to about 110 microg m(-3) (50-55 ppbv). Abnormal years in ozone concentration may skew the distribution as the mean shifts. A correlation of daily maximum ozone concentrations above 140 microg m(-3) (70 ppbv) between sites shows a division between the sites in the northern protion of the region and those in the southern portion of the region. Variations in ozone levels are well correlated over distances of several hundred kilometers, suggesting that high values are associated with synoptic scale episodes. An ozone exposure analysis also shows higher ozone exposures (250-300 ppm days) in the northerly sites as compared to the southerly sites (150-170 ppm days).

A selective spectrophotometric method for determination of copper with ferron.

A selective spectrophotometric determination of copper is based on extraction of the copper-ferron complex with tribenzylamine in chloroform at low acidity, and measurement of the absorbance of the yellow extract at 410 nm. Beer's law is found to hold up to 8 microg/ml copper concentration. Of 30 elements tested, only molybdenum interferes. The ratio copper:ferron:tribenzylamine in the extracted species is 1:2:2.

Spectrophotometric determination of vanadium after extraction as vanadium(III) picolinate.

Vanadium(V) is conveniently reduced by sodium dithionite to vanadium(III) which is extracted as its picolinate complex into chloroform. Vanadium is determined spectrophotometrically by measuring the absorbance of the complex at 385 nm against a reagent blank, Beer's law being obeyed over the range 1-50 microg/ml. The method is one of the most selective, being free from interference by relatively high concentrations of almost all the important elements, titanium, chromium, manganese, iron, cobalt, nickel, zinc, copper, aluminium, molybdenum, tungsten and uranium, found in industrial alloys. Only bismuth interferes. The method is quite simple and rapid. It has been successfully applied for the analysis of vanadium in a variety of samples.

Spectrophotometric determination of vanadium as V(III) oxinate.

Vanadium(V) is rapidly reduced by dithionite to V(III) which is extracted as the oxinate into carbon tetrachloride. Vanadium is determined by measuring absorbance of the complex at lambda(max) = 420-425 nm with a sensitivity of 0.004 microg/cm(2) and Beer's law range of 0-7 microg/ml . Several mg of some important elements can be tolerated if they are masked. Molybdenum interferes seriously. The method has been applied to synthetic samples, rutile and ilmenite with satisfactory results. Using ordinary reagents and taking 10 min or less in series for a determination, the method has a sensitivity rarely exceeded by others with a much higher tolerance for other elements.

Extraction of bivalent vanadium as its pyridine thiocyanate complex and separation from uranium, titanium, chromium and aluminium.

A simple method is described for the extraction of V(II) as its pyridine thiocyanate complex. Vanadate is reduced to V(II) in 1-2N sulphuric acid by zinc amalgam. Thiocyanate and pyridine are added, the solution is adjusted to pH 5.2-5.5 and the complex extracted with chloroform. The vanadium is back-extracted with peroxide solution. Zinc from the reductant accompanies the vanadium but alkali and alkaline earth metal ions, titanium, uranium, chromium and aluminium are separated, besides those ions reduced to the elements by zinc amalgam. The method takes about 20 min and is applicable to microgram as well as milligram amounts of vanadium.