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Biomedical subjects

G Block

Publications and source records attributed to G Block.

132 records · Page 8Linked to original sources
PubMedDate not supplied

Insulin-like growth factor-1 and growth hormone (GH) levels in canine cerebrospinal fluid are unaffected by GH or GH secretagogue (MK-0677) administration.

Elevation in circulating GH levels results in a dose-related increase in serum insulin-like growth factor-1 (IGF-1) levels in dogs. However, it is not known whether elevations in systemic IGF-1 and GH levels contribute to the cerebrospinal fluid (CSF) levels of these hormones. Therefore, a study was designed in dogs to determine if elevated circulating GH levels was a result of a GH secretagogue (MK-0677) or if exogenous GH administration resulted in increased IGF-1 and GH levels in the CSF of dogs. A total of 12 normal, young adult male dogs were randomized to three treatment groups (4 dogs/group) based on body weight. There were 4 vehicle control dogs. A group of 4 dogs were dosed orally with MK-0677 (5 mg/kg/day) dissolved in deionized water. A third group of 4 dogs received subcutaneous injections of porcine GH (pGH) at a dose of 0.1 IU/kg/day. From all dogs, blood and CSF samples were collected prior to the initiation of treatment and on days 7 and 15 of treatment. All samples were assayed using a validated radioimmunoassay. Administration of MK-0677 or pGH resulted in a statistically significant (P < or = 0.05) increased body weight gain and increased serum IGF-1 and GH levels. In contrast, administration of MK-0677 resulted in no significant (P > 0.05) increase in CSF IGF-1 or GH levels on days 7 or 15 of the study. The CSF IGF-1 values ranged from 1.2 to 2.0 ng/ml with minimal variation among three separate samples taken during the course of the study from each dog. Similarly, the CSF GH levels were very low (< 0.98 ng/ml to 2.4 ng/ml) in all dogs irrespective of treatment group. This study has demonstrated that there is no correlation between the circulating levels of IGF-1 or GH and the levels of these hormones in the CSF of normal dogs. An approximately 100-fold difference between serum and CSF IGF-1 levels in vehicle control dogs suggest that there is a blood-brain barrier for the circulating IGF-1. Similarly, failure to see an elevation in CSF GH levels despite increases in serum GH levels shows that there is a blood-brain barrier for GH in normal dogs. These results suggest that the likely source of GH and IGF-1 in the CSF of dogs is from the CNS.

Animals↗
PubMedDate not supplied

Respiratory health at a pulpmill in British Columbia.

The respiratory parameters of 392 white male pulpmill workers were measured by standardized procedures and compared with those of 310 white male rail yard workers. The pulpmill workers complained more frequently of wheezing and chest tightness and missed work more commonly because of chest illness as compared with the rail yard workers. Significant airflow obstruction was noted in nonsmokers who worked in the bleach plant, and it was most striking in the younger members of this group. The principal environmental contaminant in this area was chlorine at levels generally below current permissible concentrations. Members of the maintenance group--especially older members--demonstrated significantly lower forced vital capacity compared to the rail yard workers.

Absenteeism↗
PubMedDate not supplied

Total laryngectomy and permanent tracheostomy for treatment of laryngeal rhabdomyosarcoma in a dog.

An extensive, laryngeal tumor was identified in a nine-year-old, spayed female, mixed-breed dog. Clinical staging of the tumor included computed tomography. Six days prior to surgery, a percutaneous gastrostomy tube was placed under endoscopic guidance. Surgical treatment included total laryngectomy and permanent tracheostomy. The histologic diagnosis of the tumor was rhabdomyosarcoma. There were no major postoperative complications, and there have been no signs of local recurrence, metastatic disease, or long-term complications associated with the surgical procedure during an 18-month follow-up period.

Animals↗
PubMedDate not supplied

Determinants of plasma ascorbic acid in a healthy male population.

The antioxidant properties of vitamin C may be involved in the prevention of cancer. The correlation between dietary vitamin C intake as estimated by a dietary questionnaire and plasma ascorbic acid (AA) was examined in 68 nonsmoking male volunteers aged 30-59 years. Determinants of plasma AA as well as interrelationships between various antioxidants in plasma were also explored. The determinants of plasma AA were examined by a multiple regression model containing dietary vitamin C, calories, body weight, and amount of beverages consumed. Higher vitamin C intake (P < 0.0002) increased plasma AA, while greater body weight (P < 0.005) decreased plasma AA. A significant correlation (r = 0.43; P < 0.0003) between vitamin C intake and plasma AA was observed. There was a negative correlation between plasma AA and plasma uric acid (r = -0.32; P < 0.007) and positive associations between plasma beta-carotene and plasma alpha-tocopherol (r = 0.39; P < 0.001) and between plasma beta-carotene and plasma glutathione peroxidase (r = 0.32; P < 0.008). Vitamin C supplement users had higher plasma AA compared to nonusers. The relationship between plasma AA and vitamin C intake appears to be curvilinear with the non-supplement users at the linear part of the curve and the supplement users at the plateau. Plasma AA is an appropriate biomarker, in our subjects, of dietary vitamin C except for people consuming large amounts of this vitamin either in their diet or in supplemental form.

Adult↗
PubMedDate not supplied

Determinants of plasma vitamin E in healthy males.

Vitamin E or tocopherol, a known antioxidant, may play a role in the etiology of chronic diseases such as cancer and heart disease. This study examined both "internal" (lipids, lipoproteins, and apoproteins) and "external" (dietary components, physical activity, and body mass index) factors which may influence plasma alpha-tocopherol and gamma-tocopherol levels. Analyses were done using dietary questionnaires and plasma obtained from 65 nonsmoking male volunteers aged 30-59 years. Forty-six men did not take any supplements while 19 took supplements containing vitamin E. A positive correlation (r = 0.32; P < 0.01) between vitamin E intake and alpha-tocopherol status [(ratio of plasma alpha- or gamma-tocopherol/(total triglycerides + total cholesterol)] and a negative correlation (r = -0.33; P < 0.007) between intake and gamma-tocopherol status were observed. The main internal factors, or determinants, for plasma alpha-tocopherol for nonsupplement users were plasma triglycerides and apoproteins, apoA1 and apoB, but neither lipids nor apoproteins appeared to affect tocopherol levels in supplement users. External determinants of alpha-tocopherol status in nonsupplement users were vitamin E intake, total fat intake, and body mass index, while in supplement users only vitamin E intake was important. Both vitamin E intake and alcohol intake appeared to affect plasma gamma-tocopherol status in a negative manner.

Adult↗