The effects of hyperthermia and ionizing radiation in normal and ataxia telangiectasia human fibroblast lines

The effects of 45 degrees C hyperthermia and gamma radiation have been studied in three normal human fibroblast lines (GM38, GM730, WI38) and compared to the effects in two lines derived from patients with the hereditary disease ataxia telangiectasia (AT3BI, AT5BI). All lines, both normal and gamma-sensitive AT, showed a similar resistance to killing by heat alone, suggesting that the defect responsible for the increased radiation sensitivity in AT lines does not confer increased heat sensitivity. Shouldered survival curves were obtained in each case indicating the ability to accumulate sublethal heat damage. All normal and AT cell lines exhibited increased resistance to the lethal effects of heat in response to a thermal stress, indicating that the defect that causes radiosensitivity in AT cell lines does not prevent the induction of thermotolerance. Heat (45 degrees C, 30 min) was shown to increase the sensitivity of the normal cell lines to killing by gamma radiation. The thermal enhancement ratios obtained ranged from about 2.5 to 3.0. The same heat treatment, however, produced very little increase in the radiation sensitivity of the AT cells. Thermal enhancement ratios of about 1.2 were obtained in these lines. We hypothesize that, in normal cells, this heat treatment inactivates the process which is already defective in AT lines, and that this process may be required for the proper rejoining of double-strand breaks produced during the repair of other radiation-induced lesions.

Hormonal and chemical modulation of ventromedial hypothalamic neurons responsive to vaginocervical stimulation

Neurons of the ventromedial hypothalamus (VMH) in female rats were electrophysiologically recorded via multibarrelled glass micropipettes and tested for responsiveness to vaginocervical stimulation as well as to a variety of other peripheral stimuli. A small percentage of VMH neurons were found to be specifically responsive to vaginocervical stimulation (type I response) in the ovariectomized animal. Priming the rats with estrogen (E) and progesterone (P) significantly increased the percentage of neurons responding specifically to vaginocervical stimulation but had no effect on the percentage of nonspecifically responding (type II) and nonresponding (type III) neurons. Pharmacological testing of all three types of VMH neurons was accomplished by iontophoretic application of luteinizing hormone releasing hormone (LHRH), prolactin (PRL), and dopamine (DA) to the cell membrane. PRL excited the majority of neurons tested and DA inhibited the majority of tested units regardless of the hormonal condition of the animal or the response elicited by vaginocervical and peripheral stimulation, LHRH, however, produced changes in firing rate which were related to the type of response evoked by vaginocervical stimulation. In E-P-primed animals, neurons which were specifically or nonspecifically affected by vaginocervical stimulation responded to LHRH in a similar manner whereas a different LHRH response profile was obtained in those neurons which were not effected by vaginocervical stimulation. The results indicate that an afferent pathway from the vaginocervix to the VMH exists, that E-P priming in some manner increases the probability that a VMH neuron will respond specifically to vaginocervical probing, and that the effect of LHRH is different in neurons responding to vaginocervical stimulation than in nonresponding neurons.

Construction of a simple spike counter for analysis of electrophysiological recording data

A method for constructing a simple spike counter from a conventional calculator by taking advantage of the "adding display to memory" function [(M+) key] is described. The modification involves connecting the (M+) key to a dissecting pin and to a metallic notebook binder which is taped on to a transparent plastic sheet. The plastic sheet can then be placed on top of a polygraph record. After entering "1" into the calculator, a spike can be counted by making a single contact between the pin and the metal fastener. The total number of spikes counted can be displayed on the calculator by pressing the key for memory recall. The spike counter described herein is suitable for counting extracellular action potentials recorded on chart paper as well as other biological signals such as the rate of contraction of muscle.

Carotid artery disease in NIDDM diabetes

A prospective study of 135 controls, 286 non-insulin-dependent diabetic patients, and 31 subjects with an elevated fasting plasma glucose was performed to assess the prevalence of high-grade carotid artery stenosis. The carotid artery evaluation was performed using an ultrasonic duplex scanner. When those patients with an elevated fasting plasma glucose and non-insulin-dependent diabetes were considered together, the prevalence was 8.2% as compared with 0.7% for the controls (P = 0.0007). Those risk factors found to be significantly related to the higher prevalence of carotid disease in the combined groups of patients included age, ratio of systolic blood pressure to diastolic blood pressure, plasma cholesterol, and cigarette smoking. These findings may be an explanation for the greater incidence of stroke in patients with diabetes mellitus.

The use of directional Doppler ultrasound in the assessment of saphenofemoral incompetence

The prevalence of saphenofemoral incompetence in a series of 105 consecutive patients undergoing saphenofemoral ligation as part of an operation for primary varicose veins was determined using a directional continuous-wave Doppler ultrasonic device. Saphenofemoral incompetence was correctly predicted in 97% of limbs. Using conventional clinical methods, incompetence was correctly predicted in 82% of limbs. This difference was highly significant (P less than 0.01 McNemar). It is concluded that a directional Doppler ultrasonic assessment is a useful aid in the pre-operative determination of saphenofemoral incompetence.

Cardiac beri beri--an old disease in modern Singapore--2 case reports

This case report presents two Malay brothers who developed acute high output congestive cardiac failure within two weeks of each other. They gave a history of excessive alcohol consumption for six months, and glue sniffing for one year. The serum pyruvate levels were elevated in both prior to treatment. Haemodynamic studies were done in the second brother, and measurements obtained before, during and after treatment. A dramatic clinical response to parenteral thiamine was observed in both patients in the acute stage. The haemodynamic study was repeated after three months and showed a normal pattern.

The use of common carotid waveform analysis in the diagnosis of carotid occlusive disease

Duplex scanning with spectral analysis of the pulsed Doppler signal are currently used to detect and classify disease at the carotid bifurcation. Although the sensitivity of the test exceeds 90%, the method has a lower specificity which ranges between 8 and 50%. The poor specificity is due to the difficulty in distinguishing flow disturbances normally present at the carotid bifurcation from those produced by minimal amount of disease. In order to improve the ability of the method to predict normalcy, new features measured from the low common carotid waveform are evaluated on 150 sides. The difference of frequency from the systolic peak (a) to the point of first zero slope after peak systole (b) was used to define the ratio (a-b)/a. A ratio greater than 0.5 was associated with 76% of the normal sides and only 7% of the diseased sides. A ratio below 0.5 was associated with 83% of the diseased sides. This ratio, when used alone, can improve the specificity of the method to 76%.

Von Recklinghausen's disease associated with gastrointestinal carcinoid tumors

The occurrence of both gastrointestinal carcinoid and von Recklinghausen's disease in the same patient is uncommon. There seems to be a predilection for ampullary carcinoids in these patients. This article reports the sixth case, including a review of the literature and a brief discussion of the implications of this finding. A carcinoid tumor should be suspected in any patient with von Recklinghausen's disease presenting with gastrointestinal bleeding, obstruction, abdominal pain, and particularly obstructive jaundice.

Postoperative wound infections: a study of bacteriology and pathogenesis

Of 200 patients, 6.5% were skin carriers of Staphylococcus aureus and 3.5% became skin carriers after admission. Development of skin carrier state was associated with a long preoperative hospital stay. A second study of 275 cases showed that skin carriers of S. aureus had a significantly higher subsequent staph wound infection rate than non-carriers, but nose and/or throat carriers of S. aureus did not. Peroperative wound contamination was a significant factor in the subsequent development of wound infection. In clean surgery the infection rate was 5.9%. Both wound contamination and infection was due to gram positive organisms, usually S. aureus. When the gastrointestinal or biliary tract had been opened, the infection rate was 28%, the usual contaminating and infecting organisms were enteric and only occasionally S. aureus. There is a need for improved methods of minimizing peroperative wound contamination.

Action of prolactin, dopamine and LHRH on ventromedial hypothalamic neurons as a function of ovarian hormones

The effect of iontophoretically-applied prolactin, dopamine, LHRH and LHRH-antagonist analog on the electrical activity of neurons (n = 192) located in the ventromedial nucleus of the hypothalamus (VMH) was studied in untreated and hormone-treated ovariectomized female rats (n = 63). The spontaneous electrical activity of VMH neurons was unaffected by the presence or absence of the ovarian hormones. Neuropharmacological studies indicate that the iontophoretic deposition of prolactin and dopamine produced opposing results, in that prolactin increased the electrical activity of the majority of the VMH neurons tested while dopamine decreased their activity. Finally, the application of LHRH and LHRH-antagonist analog to VMH neurons resulted in a marked suppression of their electrical activity that was even more pronounced in the presence of ovarian hormones. The present work provides evidence at the electrophysiological level of hormonal influences on the responsiveness of VMH neurons to LHRH and its antagonist analog, and demonstrates a relationship between the responsiveness of VMH neurons to prolactin and dopamine.

Evaluating carotid artery disease. The concordance between pulsed Doppler/spectrum analysis and angiography

The results of ultrasonic pulsed Doppler duplex scanning with spectral analysis and computer pattern recognition are compared with the results of contrast arteriography in patients screened for extracranial carotid artery disease. The intraangiographer variability (one radiologist reading the same films twice) and the interangiographer variability (two radiologists reading the same film independently) were also studied. To calculate degrees of agreement corrected for chance, the Kappa statistic was computed for all the evaluation methods employed. At the present time, the concordance between spectral analysis and cerebral contrast angiography reaches a Kappa value of 0.682 +/- 0.064. This level of agreement compares favorably with the interangiographer agreement level (K = 0.568 +/- 0.058) and the intraangiographer agreement (K = 0.711 +/- 0.054). The computer pattern recognition program predicted the degree of stenosis by angiography with an agreement of K = 0.721 +/- 0.059. This concordance compares favorably to that observed when the radiologists are compared with themselves and is greater than that reached by two different radiologists. The continuous improvement in precision and accuracy of duplex scanning offers the promise of its usefulness in clinical and epidemiological studies.

Evaluation of extracranial carotid artery disease by ultrasonic duplex scanning: a clinical perspective

The development of noninvasive methods of extracranial carotid artery evaluation over the past decade has led to questions as to their usefulness in daily clinical practice. They have generally been proposed for use in screening asymptomatic patients with bruits or those about to undergo major operative procedures. Since patients with focal symptoms are considered candidates for arteriography, noninvasive tests in this situation may be redundant. However, as the accuracy of the imaging and pulsed Doppler methods has improved, it is appropriate to re-examine this question. Based upon our experience, it is our current feeling that initial screening using ultrasonic Duplex scanning does have a place in symptomatic patients and can be shown to be cost effective.

Studies of testicular and epididymal damage in relation to the occurrence of antisperm antibodies

The relationship between testicular histopathology, follicle stimulating hormone levels, sperm density and the presence of antisperm antibodies was investigated. There was no association between damage to the seminiferous tubules and the presence of agglutinating or immobilising antisperm antibodies. In 2 patients with congenital obstructive azoospermia and pre-biopsy circulating antisperm antibody there was extensive lymphocytic, macrophage and plasma cell infiltration, fibrosis and perivasculitis on epididymal biopsy. Breaches in the blood epididymis barrier are worthy of further investigation when considering the genesis of antisperm antibodies.

Norepinephrine-induced elevation of acetyl coenzyme A in rat pineal glands in culture

A micromethod for the determination of acetyl coenzyme A was developed and the relationship between the concentration of acetyl coenzyme A and the activity of rat pineal serotonin N-acetyltransferase was studied. Acetyl coenzyme A was determined by converting it into N-acetylserotonin using rat liver serotonin N-acetyltransferase. Subsequently, the hydroxy group of N-acetylserotonin was O-methylated by hydroxyindole-O-methyltransferase and S-[methyl-3H]adenosyl-l-methionine to form [3H]melatonin, which was then conveniently separated from S-[methyl-3H]adenosyl-l-methionine by thin-layer chromatography. The amount of radioactivity in melatonin is a measure of acetyl coenzyme A concentration. This method is sensitive and specific, since it can detect as low as 5 pmol of acetyl coenzyme A but not structurally related substances such as coenzyme A, adenosine diphosphate, cysteamine, D-panthothenic acid, or sodium acetate. After treating cultured rat pineal glands with l-norepinephrine (10 microM) for 6 hr, the concentration of acetyl coenzyme A was increased significantly from 3.26 +/- 0.37 to 10.24 +/- 0.93 pmol/gland, while the activity of serotonin N-acetyltransferase increased 68-fold. This result suggests that acetyl coenzyme A may play an important role in the norepinephrine-induced induction of serotonin N-acetyltransferase. Sensitivity and adaptability of this method can be utilized to measure acetyl coenzyme A in discrete regions of rat brain and in experimental conditions in which micromeasurement of acetyl coenzyme A may be required.

Serotonin N-acetyltransferase and its regulation by pineal substances

The regulation of activity of serotonin N-acetyltransferase (NAT) in pineal glands of various mammalian hierarchies may be species-specific, mediated by different mechanisms and brought about by interactions with dissimilar receptor sites. In addition to norepinephrine, serotonin and gamma-aminobutyric acid (GABA) seem to modulate NAT activity. Furthermore, preliminary studies provide evidence for the existence in pineal gland of a thermo-stable proteinaceous substance (NIS) which inactivates NAT but not other enzymes involved in the synthesis of melatonin. Inactivation of NAT by NIS is blocked by addition of 0.5 mM acetyl coenzyme A, but not coenzyme A, 0.1 M NaF or 4 mM beta-mercaptoethanol. In addition, protein dephosphorylation and disulfide exchange mechanisms are not involved in this NIS-mediated inactivation of NAT. In rat brain, the inactivating substance was found only in the pineal gland and was undetectable in other tissues. We postulate that the collective interaction among norepinephrine, serotonin, GABA, acetyl coenzyme A, NIS and NAT may regulate the synthesis of melatonin in the pineal gland.

Perioperative preservation of myocardial ultrastructure and high-energy phosphates in man

To establish whether hypothermic crystalloid potassium cardioplegia given in multidose fashion provides adequate preservation of myocardial ultrastructure and high-energy phosphates, we studied 25 patients with an ejection fraction of 50% or higher who were undergoing cardiac procedures. Eight patients had three biopsy specimens taken from the left ventricular apex for determination of adenosine triphosphate (ATP) and creatine phosphate (CP). Specimens were taken immediately prior to aortic cross-clamping, immediately after the release of the aortic cross-clamp, and 30 minutes after the release of the cross-clamp. Seventeen patients had six specimens taken form the left ventricular apex at the above-stated times, three for ATP and CP determination and three additional specimens for electron microscopy. One patient had a small perioperative infarction and another patient died on the fifth postoperative day of an aortic dissection. The mitochondria on the electron microscopic specimens were graded on a scale from 0 to 4 (4 = severe changes). There was no significant difference in the mitochondrial scores. The preservation oh high-energy phosphates was less complete. ATP was reduced to 78% (3.4.2) of control and CP was reduced in the immediate postclamp period to 32% (081/2.5)of control. The difference are particularly significant if one looks at patients whose aortic cross-clamp time was 90 minutes or more (12 patients). In this group, ATP an CP preservation were 71% of control (3.33/4.60 mmoles/kg. wet weight) and 53% of control (l.48/2.81), 30 minutes after clamp removal (p equal to or less than 0.01). We conclude that hypothermic potassium cardioplegia gives excellent preservation of the myocardial ultrastructure in man. However, the preservation of high-energy phosphates with this technique is imperfect.

Effects of norepinephrine on pineal tryptophan hydroxylase, using an improved [14C]CO2-trapping microtechnique

The synthesis of many biogenic amines involves hydroxylation and/or decarboxylation reactions. These enzymes are often measured by trapping and be determining the concentrations of their end products [14C]CO2, from carboxyl-labeled substrates. An improved [14C]CO2-trapping technique has been developed for microassay of tryptophan hydroxylase activity. This technique allows hydroxylation and decarboxylation reactions to be carried out sequentially in microculture tubes containing reaction mixtures in less than 50 microliter. The incubation vessel consists of two microculture tubes connected by a latex tubing serving as a sleeve. One of the two microculture tubes were used to carry out enzymatic reactions and the other one was filled with CO2-trapping agent to trap [14C]CO2. The utility of this technique was tested by measuring the effects of biogenic amine on tryptophan hydroxylase in bovine pineal explants in culture. The bovine pineal tryptophan hydroxylase was found to have a specific activity of 8.93 pmol/mg protein/min, and its activity was linear with respect to both incubation time and to protein concentrations. In addition, treatment with norepinephrine of both rat pineal gland and bovine pineal explants in culture for 2, 4, and 6 hr had no effect on the activity of tryptophan hydroxylase. It is believed that this technique may be adapted easily to measure numerous CO2-generating enzymatic reactions whenever the amounts of protein or the size of tissue demands the application of a microtechnique.

Evidence for existence of a serotonin N-acetyltransferase inactivating substance in rat pineal gland

This study provides evidence for the existence of an inactivating substance in pineal glands, which may be responsible for the rapid inactivation of serotonin N-acetyltransferase seen in vivo and in vitro. This serotonin N-acetyltransferase inactivating substance enhances the thermal inactivation of the norepinephrine-stimulated serotonin N-acetyltransferase activity in rat pineal homogenate. Inactivation of serotonin N-acetyltransferase by the inactivating substance and the thermal inactivation of serotonin N-acetyltransferase at 37 degrees C exhibit the following identical properties. Both processes affect serotonin N-acetyltransferase without effect on other melatonin-related enzymes; can be blocked by addition of 0.5 mM [3H] acetyl CoA, but not coenzyme A in the preincubation mixture; and were unaffected by 0.1 M NaF or 4 mM beta-mercaptoethanol. These data are interpreted to suggest that protein dephosphorylation and disulfide exchange mechanisms are not involved in either inactivation processes. Unlike serotonin N-acetyltransferase, which is highly thermo labile, the inactivating substance is thermo stable at 37 degrees C for 40 minutes. In rat, the inactivating substance was found only in the pineal gland and was undetectable in other tissues. The inactivating substance is protein in nature, since it is not dialyzable but is inactivated by boiling or treatment with trypsin. The substance, which was able to inactivate serotonin N-acetyltransferase isolated from rate liver, exhibited no diurnal variation and its activity in rat pineal gland in culture was not influenced by norepinephrine. It is postulated that the interaction among acetyl coenzyme A, serotonin N-acetyltransferase and serotonin N-acetyltransferase inactivating substance may collectively regulate the synthesis of melatonin in pineal gland.

The kinetics of norepinephrine-induced stimulation of serotonin N-acetyltransferase in bovine pineal gland

Fresh pineal explants were cultured in medium 199 containing 0.1 mg/ml of ascorbic acid, 2 mM glutamine, and 0.1% BSA in 95% O2 and 5% CO2 from 1 to 10 h. Norepinephrine (10 micrometers) increased serotonin N-acetyltransferase (NAT) activity from 2.36+ / -0.23 to 6.98+ / -0.46 pmol product produced/mg protein/min (unit), without influencing tryptophan hydroxylase, 5-hydroxytryptophan decarboxylase, monoamine oxidase, or hydroxyindole-O-methyltransferase. Dibutyryl cyclic AMP (1 mM) also stimulated NAT from 1.39+ / -0.12 to 4.33+ / -0.65 U. The norepinephrine-induced stimulation of NAT was blocked by GABA (10 micrometers), by dl-propranolol (20 micrometers), by cycloheximide (30 micrometers), by puromycin (20 micrometers), but not by actinomycin D (10 micrometers). Comparing the kinetics of native and stimulated NAT, the occurred changes in Vmax with regard to both substrates - tryptamine (from 0.885 to 3.44 U) and acetyl CoA (from 3.45 to 9.10 U) - without changes in Km with respect to both tryptamine (Km = 5 micrometers) and acetyl CoA (Km = 50 micrometers). The results of this investigation are interpreted to indicate that the norepinephrine-induced stimulation of NAT may be due to enhanced protein synthesis involving translational or post-translational events. Furthermore, the enhanced protein synthesis is coupled through activation of beta-receptor and cyclic AMP mediated actions in pineal gland. The precise interrelationship between GABA and norepinephrine in mediating and perhaps in controlling the biological events in the bovine pineal gland still awaits clarificaton.