Hypothermia differentially affects tuning curves generated by forward and by simultaneous masking.

In the gerbil maintained at euthermic (37.5 degrees C) conditions, forward masking produces a compound action potential tuning curve (CAP TC) which is less sensitive but more sharply tuned than that which is generated by simultaneous masking. These differences between forward- and simultaneously-masked CAP TCs are minimized at hypothermic (30 degrees C) conditions. The unmasking effect occurs at both temperatures, suggesting that hypothermia does not exert these changes by eliminating two-tone suppression.     

Inhibin and age in men

OBJECTIVE: Normal elderly men are reported to have decreased testicular function despite elevated gonadotrophin levels. We wished therefore to determine if changes in testicular function occur over the age range 19-60 years. DESIGN: Single fasting blood samples were obtained between 0800 and 0900 h. PATIENTS: Working men in a large industrial company between the ages of 19 and 60 years participated in the study. MEASUREMENTS: FSH, serum immunoreactive inhibin and total testosterone were measured, the latter two as measurements of Sertoli and Leydig cell function respectively. RESULTS: The mean baseline serum immunoreactive inhibin level was significantly lower in men from the older age groups, 31-40 years (479 U/l), 41-50 years (439 U/l) and 51-60 years (415 U/l) than in men from the youngest age group, 21-30 years (613 U/l) while serum FSH was higher in men from the older age groups, 41-50 years (3.7 IU/l) and 51-60 years (6.1 IU/l) than in men from the youngest age group, 21-30 years (2.6 IU/l). There appears to be a change in both FSH and inhibin production, consistent with a primary decline in testicular function. There was no significant difference in testosterone levels between the older age group, age 51-60 years and the younger age group, age 21-30 years. However, testosterone levels were significantly lower in the 41-50 year age group, when compared with the 21-30 year, this significance levelling out at about age 45 years. CONCLUSION: The data are consistent with the hypothesis that immunoreactive inhibin reflects inhibin bioactivity, and that inhibin plays a role in the feedback control of FSH secretion in men.     

TGFβ-1 regulation of VEGF production by breast cancer cells

Background: Angiogenesis is essential for tumor growth and metastasis. Vascular endothelial growth factor (VEGF) is the most potent angiogenic factor identified to date. TGFβ-1 acts as an indirect angiogenic agent. Methods: VEGF and TGFβ-1 were measured in the serum of breast cancer patients and agematched controls and in tumor tissue of cancer patients by ELISA. VEGF protein and mRNA expression by breast tumor cell lines were examined, and the effect of TGFβ-1 on VEGF production in these cells was assessed. Results: VEGF levels were significantly higher (P=.03) in the serum of patients with breast cancer compared to age-matched controls. A positive correlation was found between serum (r=0.539) and tumor tissue (r=0.688) levels of VEGF and TGFβ-1. Metastatic MDA-MB-231 breast cancer cells produce more VEGF than do the primary BT474 cells. TGFβ-1 significantly (P<.05) increased production of VEGF. Conclusions: Breast cancer cells constitutively produce VEGF protein and mRNA. There is a relationship between VEGF and TGFβ-1 levels in breast cancer patients, and TGFβ-1 regulates VEGF expression by breast cancer cells. Presented at the 50th Annual Cancer Symposium of the Society of Surgical Oncology, Chicago, Illinois, March 20–23, 1997.     

PERFORATED PEPTIC ULCER IN THE HUNTER REGION: A REVIEW OF 174 CASES

A review of 174 consecutive patients admitted with a diagnosis of perforated peptic ulcer to eight Hunter Region hospitals during 1979–86 is presented. Among the female admissions, the proportion of patients > 70 years of age was twice that in males. One-third of all perforations were in females who accounted for two-thirds of all perforated gastric ulcers. Multivariate analysis revealed that perforations located in the stomach and older age were both significant independent variables adversely affecting outcome following surgery. In contrast, shock at presentation and delay in operating were not statistically significant independent risk factors.     

Mitochondrial DNA variability detected in a single wheat regenerant involves a rare recombination event across a short repeat

The mitochondrial genome of the selfed progeny of a plant regenerated from long-term somatic tissue culture displays specific structural rearrangements characterized by the appearance of novel restriction fragments. A mitochondrial DNA library was constructed from this selfed progeny in the SalI site of cosmid pHC79 and the novel fragments were subsequently studied. They were shown to arise from reciprocal recombination events involving DNA sequences present in the parental plant. The regions of recombination were sequenced and the nucleotide sequences were aligned with those of the presumptive parental fragments. We characterized an imperfect short repeated DNA sequence, 242 bp long, within which a 7-bb DNA repeat could act as a region of recombination. The use of PCR technology allowed us to show that these fragments were present in both parental plants and tissue cultures as low-abundance sequence arrangements.     

Early inhibition of natural and interferon-activated killers in endometrial cancer patients treated with local radiotherapy

The present study was aimed at comparing the effect of clinical staging and radiotherapy on natural killer (NK) and interferon-activated killer (IAK) cell activity in a group of endometrial cancer patients receiving a total dose of 5,000 to 8,000 rads. We report that when compared to age-matched women, a significantly higher number and percentage of patients show low NK and IAK cell activity. At diagnosis, diminished NK activity was seen in about 20% of the patients, while IAK activity was low in 49% of these patients. There was no correlation between these deficiencies and the grade or stage of the disease. In contrast, radiotherapy induced deleterious effects on both populations of NK and IAK cells. These deleterious effects were more pronounced in patients showing a low level of spontaneous NK activity. In an attempt to understand better the mechanism by which the presence of cancer itself and/or radiotherapy affects these activities, we studied in greater detail changes in peripheral blood T-cell numbers and subsets. Before radiotherapy, all lymphocyte counts were within the normal range. In contrast, after radiotherapy the absolute numbers of all T-cell subsets were significantly decreased in the majority of the patients tested, OKT4+ cells being the most radiosensitive and Leu 7+ cells the most radioresistant.