Inverse relationship between galactokinase activity and 2-deoxygalactose resistance in Chinese hamster ovary cells

Galactokinase activity is reduced in 12 independent clones of Chinese hamster ovary cells resistant to 2-deoxygalactose. The frequency of resistant colonies is increased with chemical mutagens. The resistant phenotype is stable in the absence of selection. There is an inverse correlation between the levels of galactokinase activity and the cloning efficiency in deoxygalactose. Cells with high resistance have 1% or less of the enzyme activity observed in the parental cells; while cells with low resistance have 10-30% galactokinase activity. Studies with tetraploid hybrid cells reveal that resistance to deoxygalactose is a recessive trait and that cells with high resistance do not complement those with low resistance. In cell lines with low resistance, the Km for galactose, Ki for deoxygalactose, Km for ATP, and thermolability were not significantly altered compared to sensitive parental cells. Although the possibility of mutation at the structural gene locus has not been ruled out, the reduced enzyme activity may also be due to mutation at a regulatory site which affects the number of galactokinase molecules per cell.     

A computerized obstetric medical record

Duke University has utilized computerized obstetric medical records since 1971. System evolution is described. Deficiencies in the current system appear to evolve from the computer/human interface rather than from basic system design. Critical elements in system success are physician acceptance of the appearance of data collection sheets and printed notes and continual rapid response in programing modification to allow for physician individuality and changes in medical practice. The limiting factor in the potential usefulness of such a system is the rate of incomplete data collection. It is suggested that if the physician were to enter data directly into the computer through a terminal, data collection would be more accurate and complete.     

Mortality and some biochemical changes in mink (Mustela vison) given sublethal doses of aflatoxin each day

Two feeding trials were done to study the susceptibility of mink (Mustela vison) to multiple sublethal doses of aflatoxins. In the 1st trial, twenty 3-month-old male mink were divided equally among groups. Each mink in groups 1, 2, 3, and 4 was given a meatball daily that contained 15, 30, 45, or 0 mug of aflatoxins (B1:G1, 40:60), respectively. All mink in group 3 died between the 25th and the 30th days of the feeding trial. Each mink had ingested 1,035 to 1,480 mug of aflatoxins. Four of the mink in group 2 died almost as soon as did mink in group 3. Four mink in group 1 died between 40 and 59 days after the start of the feeding trial. Generally, a marked increase in plasma cholesterol and alkaline phosphatase activity appeared before mink died. The liver from animals that died of aflatoxicosis showed prominent pathologic changes which included hemorrhages and appearance of pink yellow spots. Histopathologic examination of liver from dead mink revealed fatty infiltration, bile duct proliferation, bile stasis, pseudotubular formation, congestion, and fibrosis. The feeding trial was repeated with 20 mink (8 males and 12 females) that were 1.5 to 2 years old. In this instance, 0, 20, 40, and 60 mug of aflatoxins were administered each day. All treated animals, except 1, were dead within 37 days after the experiment started. The survivor was given the lowest dosage of toxins and died after 52 days by which time 960 mug of aflatoxins were consumed. Plasma cholesterol content and alkaline phosphatase activity generally were similar to those observed in younger mink of the 1st feeding trial.     

Irradiation of clinically uninvolved cervical lymph nodes

Of 402 patients with cancers of the oral cavity, oropharynx, and supraglottic larynx treated at Stanford between 1957 and 1972, 164 had clinically uninvolved cervical lymph nodes prior to the initiation of radiation therapy. Lymph node metastases developed later in 38 per cent of patients with primary oral cavity carcinomas who were treated with interstitial radium implants alone. No late cervical lymph node involvement was found in those patients who received high dose external irradiation to at least the primary site and first echelon lymph nodes. Lymph node failures were ultimately noted in 20 of the 140 patients (14 per cent), who received partial or complete neck irradiation, but 18 of these occurred in patients with uncontrolled primary lesions, suggesting that re-seeding of cervical lymph nodes had taken place rather than failure of the initial irradiation to control subclinical metastases. Our present policy is to treat the primary lesion and adjacent lymph nodes with high dose megavoltage techniques, combined with interstitial irradiation if possible. Bilateral supplemental inferior neck radiation ports are added for patients with advanced primary neoplasms and for those with clinically involved cervical lymph nodes. All other patients undergoing radiation therapy for stage T1 primary lesions and clinically negative necks also receive ipsilateral low neck irradiation. In addition, cervical lymph nodes are electively irradiated when the primary lesion has been resected. When these policies are adopted, the incidence of cervical lymph node failures is extremely low in patients whose primary sites remain controlled, and morbidity from the cervical radiation fields is negligible.     

Inhibition of growth and aflatoxin production of Aspergillus parasiticus by citrus oils

Aspergillus parasiticus was inoculated into grapefruit juice and a glucose-yeast extract medium; both contained 500-7000 ppm of citrus oils that were incorporated into the media by sonication. Orange and lemon oil were more inhibitory to mold growth and aflatoxin production than was dlimonene, the main constituent of the two peel oils. After 7 days at 28 degrees C, 2000 ppm of lemon and 3000 ppm of orange oil in grapefruit juice afforded maximum suppression of mold growth and toxin formation. When the glucose-yeast extract medium was used, 3000 ppm of either oil were needed to achieve the same result. After 4 days at 28 degrees C, orange oil at 3500 ppm in either medium markedly inhibited mold growth (as evidenced by dry weight of mold mycelium) and aflatoxin production (only 14 and 1% of the amount normally produced in the juice and artificial medium, respectively). Higher concentrations of orange oil further reduced mold growth and aflatoxin production and also delayed the onset of sporulation, if it occurred. Although aflatoxin was detected in all samples, only 0.2 to 0.5% of the amount found in controls (without the citrus oil) was present when the medium contained 7000 ppm orange oil. The mold consistently grew, albeit very poorly, on the glass at the liquid-atmosphere interface even when the substrate contained a large amount of citrus oil.     

Angiographic and computed tomographic correlation in cerebral venous angiomas

Venous angioma of the brain is a rare congenital vascular anomaly. In the last few years there have been several reports on the angiographic appearance of this lesion, but very little has been written about the findings on computed tomography (CT). Angiographically, the arterial phase is normal, while the capillary phase might demonstrate a blush. The major abnormality is the venous phase, where multiple dilated medullary veins converge centrally into a large drainage vein. The two cases presented here correlate the angiographic and CT appearances. It is felt that, with a knowledge of these findings, an accurate diagnosis of this condition can usually be reached.     

Demographic factors and pregnancy--who chooses abortion?

The number of pregnancies terminated as induced abortions has been analysed from data recorded in the Norwegian Birth Registry and the Norwegian Abortion File at the Central Bureau of Statistics. During the time period 1 January 1979 to 31 December 1991, 871,439 pregnant women were registered. Among single women the proportion of pregnancies terminated as induced abortions varied between 40 and 75% throughout the study period. Cohabitant women chose abortion significantly more often than married women. Among married women the proportion of pregnancies interrupted varied with the woman's age and the number of children. Among women 20-34 years of age with one or no child, more than 97% of the pregnancies proceeded to term. Women undergoing abortion comprise a heterogeneous group, judged by demographic factors. Future studies must focus on social factors as well as demographic factors, in order to uncover the complexity of the reasons for choosing abortion.     

The renin-angiotensin system in left ventricular remodeling

Left ventricular remodeling is a dynamic process that occurs in reaction to an insult to the myocardium. The response to either loss of cells, as may occur following myocardial infarction, or to hemodynamic overload, as may occur in aortic stenosis, is an attempt to maintain cardiac output and normalize wall tension. This is accomplished through the activation of the renin-angiotensin system and hypertrophy of noninfarcted segments of the myocardium. in the case of moderate or large infarctions these mechanisms fail to normalize wall stress. The stimulus to further remodeling remains, viable myocytes hypertrophy (with greater increases in cell length than width), the mass-to-volume ratio increases, and an exponential increase in wall stress results. This increase in myocyte tension has been associated with premature myocyte cell death. Thus, a vicious cycle is established wherein overstretch of the myocardium while sustaining cardiac output leads to progressive myocyte loss and left ventricular dilation. The renin-angiotensin system plays an integral role in this process. Its inhibition by angiotensin-converting enzyme (ACE) inhibitors both chronically and immediately after myocardial infarction has been shown to decrease left ventricular volumes and reduce mortality. Controversy exists regarding the mechanism through which ACE inhibitors exert their effects. ACE inhibitors reduce afterload/preload, circulating angiotensin II levels, and raise circulating levels of bradykinin. It is not yet clear which mechanism is responsible for the greatest impact on left ventricular dilation and mortality. inhibition of the renin-angiotensin system is clearly beneficial to cardiac performance as well as morbidity and mortality when myocardium is lost and heart failure ensues. Specific modes of action require further definition, including local and systemic effects. Possible benefits of angiotensin receptor blockade versus augmentation of bradykinin requires definition, setting the stage for further study, while the beneficial therapeutic use of these agents continues.