Basis for body weight exponent (0.75) as a scaling factor in energy metabolism and risk assessment

The basis that led to the adoption of the exponent (0.75) as a scaling factor for the relationship between body weight and energy metabolism is presented. In the risk assessment formulation, it may be appropriate to use the 0.75 power of body weight as a scaling factor for carcinogenicity data obtained from animal studies.

Audit of the annual reports of directors of public health: production methods

OBJECTIVE

An audit of production methods used for the Directors of Public Health (DsPH) Annual Report of the health of their local population.

DESIGN

Postal questionnaire survey.

SETTING AND SUBJECTS

23 Departments of Public Health in the West Midlands Region.

MAIN OUTCOME MEASURES

Costs and problems relating to different production techniques used.

RESULTS

The majority of DsPH favoured reports with figures and graphs. This led to most DsPH using in-house desktop publishing or employing external graphic designers. Those using the former technique had more problems related to computers and felt they spent too much medical time working on the document. However, they also valued the relative low cost, editorial freedom and the ability to correct mistakes easily. Departments which employed external graphic designers generally paid more, but appreciated the extra time made available by delegating the work. They also felt that the expertise was valuable in document design. However, inaccuracies were cited as being more difficult to correct.

CONCLUSIONS

Perhaps the best way of producing an annual report is to amalgamate the two commonest production techniques (i.e. external graphic design and in-house desktop publishing).

A simple staining procedure for detecting the true acrosome reaction in buffalo (Bubalus bubalis) spermatozoa

A simple dual staining procedure for detecting the true acrosome reaction in dried smears of buffalo spermatozoa is described. Trypan blue is used first to differentiate live from dead spermatozoa and the dried smears which have been prepared are stained with Giemsa for acrosome evaluation. Four categories of spermatozoa were recognized: A) live, intact acrosome (acrosome pink, postnuclear cap clear); B) dead, intact acrosome (acrosome pink, postnuclear cap blue); C) live, detached acrosome (acrosome clear, postnuclear cap clear); and D) dead, detached acrosome (acrosome clear, postnuclear cap blue). The procedure is simple, rapid and convenient for assessing true acrosome reaction in buffalo spermatozoa. Simultaneous assessment of sperm viability and its acrosomal status in dried smears makes this procedure attractive because the true acrosome reaction can be studied thoroughly at a later state after the incubation period.

Standard setting processes and regulations for environmental contaminants in drinking water: state versus federal needs and viewpoints

The primary objective of a standard setting process is to arrive at a drinking water concentration at which exposure to a contaminant would result in no known or potential adverse health effect on human health. The drinking water standards also serve as guidelines to prevent pollution of water sources and may be applicable in some cases as regulatory remediation levels. The risk assessment methods along with various decision making parameters are used to establish drinking water standards. For carcinogens classified in Groups A and B by the United States Environmental Protection Agency (USEPA) the standards are set by using nonthreshold cancer risk models. The linearized multistage model is commonly used for computation of potency factors for carcinogenic contaminants. The acceptable excess risk level may vary from 10(-6) to 10(-4). For noncarcinogens, a threshold model approach based on application of an uncertainty factor is used to arrive at a reference dose (RfD). The RfD approach may also be used for carcinogens classified in Group C by the USEPA. The RfD approach with an additional uncertainty factory of 10 for carcinogenicity has been applied in the formulation of risk assessment for Group C carcinogens. The assumptions commonly used in arriving at drinking water standards are human life expectancy, 70 years; average human body weight, 70 kg; human daily drinking water consumption, 2 liters; and contribution of exposure to the contaminant from drinking water (expressed as a part of the total environmental exposure), 20%. Currently, there are over 80 USEPA existing or proposed primary standards for organic and inorganic contaminants in drinking water. Some of the state versus federal needs and viewpoints are discussed.

A survey and analysis of states' methodologies for deriving drinking water guidelines for chemical contaminants

Data from a national survey questionnaire regarding the development of guidelines for chemical contaminants in drinking water were collected from all 50 states. Twenty-three states develop at least some of their own guidelines; the other 27 states rely on guidelines previously developed by the U.S. Environmental Protection Agency (USEPA) or by other states. States which derive guidelines generally employ toxicological criteria and risk assessment methodologies developed by the USEPA. Fourteen of the twenty-three states that develop their own guidelines depend on cancer potency factors derived by the USEPA to establish risk-based concentrations for carcinogens. Most of the states develop guidelines based on preventing possible excess cancer risk greater than one in one million. Seventeen of these twenty-three states rely on oral reference doses (RfDs) to derive guidelines for noncarcinogens. Examination and clarification of the states' approaches to guideline derivation reveal that although similar risk assessment techniques are generally employed, differences in assumptions, chemical classifications, and uncertainty factors may lead to variation in resultant guidance levels. Improved communication and coordination between states and the federal government may help reduce the variations and inconsistencies among the states in establishing drinking water guidelines for chemical contaminants.

Effect of uterine fluid on in vitro acrosome reaction of buffalo ( ) spermatozoa

The present study was undertaken to examine in vitro acrosome reaction in the uterine fluid of estrous buffalo. Successful acrosome reaction was achieved by incubating buffalo spermatozoa in 2% detoxified uterine fluid in Biggers Whitten Whittingham (BWW) medium, pH 7.4 at 37 degrees C and a sperm concentration of 36 x 10/ml. Neat uterine fluid has been found to be toxic to spermatozoa, hence we detoxified the uterine fluid at 56 degrees C for 30 min, which resulted in higher percentage of sperm motility, viability, and acrosome reaction. All the three stages of acrosome reaction i.e., acrosome swelling, vesiculation and shedding, were observed and they reached an apparent maximum at 4, 7 and 8 h of incubation, respectively. The significance of the findings in relation to the role of female reproductive tract in acrosome reaction is discussed.

Calmodulin-like protein in buffalo (Bubalus bubalis) seminal plasma and its effect on sperm Ca++, Mg++-ATPase

A calmodulin-like protein (CLP) has been identified in buffalo (Bubalus bubalis) seminal plasma and partially characterized. It was heat stable and had properties similar to those of the calcium-binding protein, calmodulin. It is present in relatively high concentrations in buffalo seminal plasma. When added to buffalo red-blood cell plasma membrane (RBC ghosts) it increased Ca++, Mg++-ATPase activity by 112%. The activation is counteracted by chlorpromazine and trifluoperazine, the anti-calmodulin drugs. A similar calmodulin-activated Ca++ pump has been found predominantly in the tail fractions of buffalo spermatozoa. The existence of CLP in buffalo seminal plasma may be responsible for some of the physiological changes observed during capacitation and acrosome reaction. A hypothesis has been proposed involving CLP in regulation of these events.

Identification of the uterine factor(s) which induce the acrosome reaction in buffalo (Bubalus bubalis) spermatozoa

This study characterizes factors present in uterine fluid from oestrous buffaloes which induce the acrosome reaction in buffalo spermatozoa. Characterization was performed by dialysis, heat treatment (90 degrees C, 30 min) and deproteinization of uterine fluid. The % motility and viability of sperm was maintained better in unfractionated uterine fluid than in dialysed fluid. Heating and deproteinization of the dialysed uterine fluid significantly reduced the % motility and viability of sperm. The percentage of sperm showing different stages of the acrosome reaction (swelling, and vesiculation) was significantly higher for sperm incubated in dialysed than in neat uterine fluid. There was no significant difference in the % of sperm showing acrosome shedding in both dialysed and neat uterine fluid. Heat treatment destroyed the ability of uterine fluid to induce the acrosome reaction. Sperm incubated in the protein precipitate from uterine fluid showed all stages of the acrosome reaction. Thus, the uterine factor(s) responsible for inducing the acrosome reaction in buffalo sperm was associated with the non-dialysable, albumin-like protein fraction and was heat-labile.

A Profile of Porhyrins in Cases .of Discoid Lupus Erythematosus

Porphyrin levels in nineteen cases of discoid lupus erythematosus were compared with porphyrin levels in ten controls using Rimingto.in's technique. The erythrocyte protoporphyrin, urinary uroporphyrin and faecal coproporph rin and faccal protoporphyrin were found to be significantly raised as compared to the controls.

The determination of environmental 2-ethoxyethanol by gas chromatography

A gas chromatographic procedure for the determination of 2-ethoxyethanol (C2H5OCH2CH2OH) was developed by using the general principles of analysis of solvent vapors. 2-Ethoxyethanol was sampled by adsorbing on activated carbon. It was desorbed with carbon disulfide plus 2-propanol (0.5%). The analytical column was packed with 10% free fatty acid phase on Chromosorb-P AW. The analysis was conducted at 130 degrees C isothermal using a flame ionization detector. Addition of 2-propanol (0.5%) to carbon disulfide improved (P less than or equal to 0.01) desorption of 2-ethoxyethanol adsorbed on activated carbon. The mean desorption efficiency of carbon disulfide plus 2-propanol (0.5%) was 87.9 +/- 2.86% (n = 15). Based on a 101 air sample and detector sensitivity of 2 X 10(-10) AFS, the calculated limit of detection of 2-ethoxyethanol was 0.1 ppm. The precision (coefficient of variation) for this analytical procedure was 3.34% (n = 12). In conclusion, 2-ethoxyethanol adsorbed on activated carbon can be desorbed with carbon disulfide plus 2-propanol (0.5%). Subsequently the desorbed 2-ethoxyethanol can be analyzed by gas chromatographic identification on 10% FFAP using a flame ionization detector.

Stimulation of capacitation and the acrosome reaction in ejaculated buffalo (Bubalus bubalis) sperm and the effects of a sperm motility factor

The conditions for stimulation of in vitro capacitation and the acrosome reaction of ejaculated buffalo sperm has been determined. Washed ejaculated sperm were successfully capacitated in BWW medium supplemented with bovine serum albumin (BSA) and a sperm motility factor(s) (SMF(s) isolated from the adrenal glands of rats. The acrosome reaction was induced in capacitated sperm by introducing Ca++ ions (final concentration 5 mM) into the medium. Supplementation of BWW medium with SMF(s) in the presence of BSA significantly increased the percentage of sperm showing capacitation and the acrosome reaction. SMF(s) also significantly increased the percentage motility, the percentage forward motility and maintained a higher percentage of live sperm in BWW medium under the conditions used in this study. The significance of the present findings is discussed.

Determination of vinyl acetate in air by gas chromatography

A gas chromatographic analysis for vinyl acetate is presented. Vinyl acetate was sampled by adsorbing on activated carbon. It was desorbed with carbon disulfide with a mean efficiency of 83.0%. The analytical column was packed with 10% free fatty acid phase on acid-washed Chromosorb-P. Gas chromatographic identification was also conducted on another column packed with 0.4% Carbowax-1500 on Carbopack A. Analysis was performed on a chromatograph equipped with a flame ionization detector. The precision (coefficient of variation) for the analytical procedure using a free fatty acid phase column was 4.0%. Based on a 10 litre air sample, the calculated limit of detection by this procedure was 0.1 parts per million.

A quantitative assay of porphyrins in leprosy patients. A spectrophotometric study

Quantitative estimations of porphyrin in the blood, urine, and feces of 30 leprosy patients under treatment with dapsone, ten untreated cases, and 100 normal subjects were done by Rimington's method. Dapsone had no adverse effect on porphyrin metabolism because none of the cases of leprosy under study developed statistically significantly raised porphyrin levels in the blood, urine, and stools. Although erythrocyte coproporphyrin levels were significantly higher in leprosy patients than controls and urinary uroporphyrin levels significantly lower, most values fell within the normal range. These differences did not appear to have any clinical significance, and their cause remains unknown.

A Spectrophotometric Study of Eryrhrocyte Porphyrins in Patients of Atopic Dermatitis

A quantitative assay of porphyrins in blood'of thirty patients with atopic dermatitis was done. Rimington's technique for the estimation of porphyrins was employed. Porphyrin levels in thirty cases of atopic dermatitis were compared with levels in ten controls. No satistically significant difference in porphyrin levels was observed be the study and control groups. Porphyrin were also compared between patients with and without history of photosensitivity. The, erythrocyte coproporphyrin in patients with photosensitivity was significantly higher than in patient without Photosensitivity.

A Spectrophotometric Study of Urinary Porphyrins in Patients of Atopic Dermatitis

A Quantitative assay of porphymins in urine of thirty patients of atopic dermatitis was.