Precipitation pattern formation in the copper(II) oxalate system with gravity flow and axial symmetry

Chemical systems that are far from thermodynamic equilibrium may form complex temporal and spatiotemporal structures. In our paper, we present unusual precipitation patterns that have been observed in the system of Cu(II)-oxalate. Starting with a pellet of copper sulfate immersed in or by pumping copper sulfate solution into a horizontal layer of sodium oxalate solution, we have observed the formation of a precipitate ring and an array of radially oriented thin fingers. The development of these patterns is related to the internal structure of the different crystals, the gravity flow, and the circular symmetry of the experimental arrangement.

The clinical implications (or lack thereof) of vegetations detected by echocardiography in patients not thought to have endocarditis

BACKGROUND

The clinical impact of echocardiographic demonstration of a vegetation (Veg) in patients in whom infective endocarditis (IE) is not suspected has not previously been analyzed.

HYPOTHESIS

In this study, an echocardiographic database was interrogated to test whether discovery of a vegetation by echocardiography should result in treatment for endocarditis if IE is not suspected.

METHODS

In all, 2,750 serial transthoracic echocardiograms (TTE) were reviewed to generate a list of reports containing the word Veg or thickening (Thk). A chart review of cases identified the impact the report had on patient management. To analyze reader bias due to echocardiographic requests, stating "rule out Veg or IE" as the reason for the study, an additional 1,000 serial TTE requests were segregated into two groups with and without this term. The incidence of the terms Veg or Thk in TTE reports of these groups was tabulated.

RESULTS

Of 2,750 reports, 20 contained the word Veg. Blood cultures were drawn in 16 of 20, with 7 of 16 being positive. Therapy for IE was initiated in 5 of 7 patients with positive cultures. Of 1,000 requests reviewed in the second phase, 24% of those with rule out Veg as the indication for TTE (n = 29) had Veg and 7% had Thk, while in 971 cases with other indications for TTE 0.2% had Veg and 9.3% had Thk.

CONCLUSIONS

Clinicians disregard TTE demonstration of Veg if clinical suspicion for IE is low. It is not clear whether the initial echo request biases the interpretation.

Racial differences in patients with heart failure

BACKGROUND AND HYPOTHESIS

Limited data exist regarding racial differences in heart failure. The objective of this prospective study was to document racial differences in the baseline demographics and patterns of health care utilization and outcomes in patients with heart failure.

METHODS

The data on 163 consecutive patients (113 black, 50 white) admitted with a diagnosis of heart failure confirmed by pulmonary congestion on chest x-ray were prospectively evaluated. Patient demographics, physical examination findings at admission, comorbid conditions, and medications at admission and discharge were analyzed. Follow-up was performed to document visits to the physician's office after discharge and readmission rate during a 6-month time period.

RESULTS

Compared with whites, blacks were younger in age (mean age 63.8 +/- 13.7 years vs. 70.8 +/- 13.1, p = 0.003), and had a higher prevalence of hypertension (86 vs. 66%, p = 0.004), left ventricular hypertrophy (24 vs. 8%, p = 0.02), ejection fraction < 40% (64 vs. 43%, p = 0.03), and readmission rate (33 vs. 18%, p = 0.05). Whites had a higher prevalence of atrial fibrillation (42 vs. 21%, p = 0.006) and more frequently followed up with their cardiologists as outpatients (58 vs. 39%, p = 0.04).

CONCLUSION

Significant racial differences exist in patients with heart failure with regard to age, incidence, etiologic factors, left ventricular hypertrophy, left ventricular function, and clinical follow-up. It is important to consider these racial differences in the evaluation and management of patients with heart failure.

Epidemiological and etiological study of oral submucous fibrosis among gutkha chewers of Patna, Bihar, India

An etiological and epidemiological study of oral submucous fibrosis (OSMF) has been done in Patna, Bihar. Total 157 cases of OSMF and 135 control subjects were selected for study in the period of 2002-2004. It was observed that Male:Female ratio was 2.7:1. The youngest case of OSMF was 11 year old and the oldest one was 54 years of age. Maximum number of cases were belonging to 21-40 years of age and they were belonging to low or middle socioeconomic class. Most of the OSMF cases used heavy spices and chillies, where as control mild spices and chillies. Gutkha was the most commonly used by the OSMF cases only 3 per cent did not use any gutkha or other areca nut product where as 80 per cent control did not have any chewing habit. The OSMF cases used gutkha and other products 2-10 pouches per day and kept in the mouth for 2-10 minutes and they were using since 2-4 years. Most of the OSMF cases kept gutkha in the buccal vestibule or they chewed and swallowed it, only a small number of patients chewed and spitted it out. It was also observed that OSMF developed on one side of the buccal vestibule where they kept the chew and other side was normal.

The relationship of functional status, nutritional assessment, and severity of illness to in-hospital mortality

BACKGROUND

Prediction of in-hospital mortality may direct hospital resources towards those patients most at risk. A number of single domain risk instruments have been developed, indicating that functional status, nutritional assessment, and severity of illness individually predict in-hospital mortality. The interaction among these predictors is less well described.

OBJECTIVE

To determine the relationship of functional status, nutritional assessment, and severity of illness to in-hospital mortality.

DESIGN, SETTING, SUBJECTS

Cohort study of 1712 consecutive admissions over a one year period to an Internal Medical Service at a tertiary university teaching hospital.

MAIN OUTCOME MEASURES

Death during hospital admission.

RESULTS

Dependency in activities of daily living (OR = 3.37, 95% CI 1.78 to 6.37, p = 0.0002) and body mass index less than 20 (OR = 2.38, 95% CI 1.20 to 4.74, p = 0.01) predicted in-hospital mortality after adjusting for nutritional risk assessment, and severity of illness score.

CONCLUSIONS

Impairment in functional status and low body mass index produce the best predictors of inhospital mortality, after adjusting for nutritional risk and severity of illness score. Among these factors, functional impairment may be amenable to correction.

Pharmacokinetics of theophylline in preterm neonates during the first month of life

OBJECTIVE

The present work aimed to estimate the theophylline pharmacokinetic parameters (TH-PKP) in preterm neonates with apnea during the first month of life in order to optimize its dosage regimen.

METHODS

Fifty preterm neonates enrolled in the study with recurrent apnea were admitted during 1998-2000 to the Neonatal Intensive Care Unit of Maternity and Children's Hospital, Al-Mosaida, Jeddah, Kingdom of Saudi Arabia. Criteria for this study were preterm with gestational age (GA) of 26-33 weeks (mean +/- SD 30 +/- 3.9). They received TH of 3-6 mg/kg loading dose (LD) followed by maintenance dose (MD) of 0.5 - 3.0 mg/kg/12 hours. Eight of these patients received phenobarbital and 19 received cimetidine concomitantly for at least 7 days. Blood samples were taken one hour post LD and at steady state (Css). Theophylline levels were determined by fluorescence polarization immunoassay.

RESULTS

Phenobarbital significantly enhanced TH clearance (CL) and reduced its half-life (t0.5) but cimetidine had no significant effect. Excluding patients receiving phenobarbital. The mean +/- SD TH-PKP were volume of distribution (Vd) = 0.77 +/- 0.25 L/kg; elimination rate constant (Ke) = 0.027 +/- 0.011 h(-1); CL = 0.019 +/- 0.006 L/h/kg, t0.5 = 30.7 +/- 12.1. There was marked intra patient variability in all TH-PKP.

CONCLUSION

In view of the results and practical considerations, initial dosage regimen to attain a TH Css level within the therapeutic range (6-12 ug/ml) was suggested: LD 6-7 mg/kg, MD 1.5 - 2.0 mg/kg/12 hours. To compensate for maturation changes or drug interaction, a method, based on estimation of individual TH CL, was described for adjusting MD.

Genomic variations among wildtype and mutant strains of pseudorabies virus

Both wild-type virulent and mutant strains of pseudorabies virus (PrV) were used in this study. Mutants used were derived from the plaque purified strain PrVmAIP. A total of six drug resistant mutants, three bromodeoxyuridine (BUdR) resistant and three iododeoxyuridine (IUdR) resistant, respectively, were isolated and passaged in chicken embryo fibroblast (CEF) cells. The DNA of these PrVs were compared with the wild-type isolates by means of the restriction fragment pattern (RFP) findings produced with Bam HI, Kpn I, Hind III and Bgl II restriction enzymes (RE). Compared to the wild-type PrVs (PrV-VBA1-parental strain of PrVmAIP; PrV-VBA2; PrV-VBA3), the RFP of PrVmAIP showed the presence of mutations within the RE sites studied. Both PrV-VBA1 and PrV-VBA2 appeared to be closely related but their RFPs differed from PrV-VBA3. Significant differences either in the number, size or migrations of the DNA fragments could also be detected in the BUdR resistant strains. Even though different features of cytopathic effect (GPE) were observed in the IUdR resistant PrVs, the RFP findings remained identical. The PrVs studied showed considerable differences from the reference PrV (PrV-CD).

An evaluation of theophylline dosing. Suggested by the Saudi national protocol for children with severe asthma

OBJECTIVE

To evaluate the impact of Saudi national protocol on the diagnosis and management of asthma for optimizing theophylline use in children with severe asthma. To also review theophylline clearance and provide guidelines for individualization of doses.

METHODS

Theophylline level was estimated in blood samples of 66 children with severe asthma who were admitted to King Abdulaziz University Hospital during the period 1998-1999. The theophylline doses given to these patients was reviewed and patients were categorized into 2 groups: Group one had received doses recommended by Saudi national protocol +/- 10%, group 2 had received doses <90% of that recommended by Saudi national protocol. The distribution of theophylline levels in blood samples of each group was estimated. Theophylline steady state level was used to estimate theophylline clearance using a standard pharmacokinetic equation.

RESULTS

Out of the total samples from group one, 70% of theophylline levels were within therapeutic range, while only 10% of the total samples of group 2 were within therapeutic range. The mean theophylline clearance in children (1-8 years) was estimated as 0.092 +/- 0.023 and was found significantly higher than the mean theophylline clearance (0.069 +/- 0.014) which is observed in older children (9-13 years).

CONCLUSION

Saudi national protocol theophylline dose guidelines had a favorable impact on the optimization of theophylline use in children with severe asthma. Guidelines that ensure accurate adjustment of doses on individual basis in view of drug level were suggested.

Detection of hTERT protein by flow cytometry

Telomerase is a telomere-specific DNA polymerase consisting of protein and RNA components, which is activated in germline cells and the majority of cancers and serves to counter the consequences of telomere shortening. The protein component, hTERT, is believed to be the catalytic subunit of human telomerase and its expression at the mRNA level correlates well with telomerase activity in vitro. Current techniques for assaying telomerase activity detect only the mean activity in a sample and are unable to isolate specific cell sub-populations. This report describes the development and validation of a cellular, immunofluorescence-based flow cytometry assay that allows detection of intranuclear hTERT while maintaining identifiable cell population characteristics. The assay was shown to be both sensitive to changes in telomerase expression and was semi-quantitative. In both cell line differentiation experiments and in primary cells, a good correlation existed between hTERT expression measured by flow cytometry and telomerase activity detected by the telomeric repeat amplification protocol (TRAP). The method developed offers a quick, simple and reproducible cellular-based assay for hTERT expression. This assay will provide a useful, new tool for future investigations, facilitating the analysis of hTERT expression in mixed cell populations.

Clinical predictors of heart failure in patients with first acute myocardial infarction

BACKGROUND

The occurrence of heart failure associated with an acute myocardial infarction has a strong adverse effect on long-term morbidity and mortality. The prediction and prevention of heart failure could influence these adverse events.

METHODS AND RESULTS

We studied 483 consecutive patients who had their first acute myocardial infarction and who were admitted within 24 hours of the onset of symptoms. Heart failure was defined as the presence of pulmonary rales or an S3 gallop, or the presence of alveolar or interstitial edema by radiograph. Baseline demographic data, determination of peak creatine phosphokinase level, echocardiographic left ventricular ejection fraction, blood pressure, and pulse were obtained. Heart failure occurred in 41.6% (201 of 483) of the patients. We observed a bimodal occurrence of heart failure with an early occurrence at admission in 4% (20 of 483) followed by a second increase beginning after the fourth day of admission in 39% of the remaining patients (181 of 463). Predictors of early heart failure were older age, diabetes mellitus, or previous cardiac symptoms, whereas the predictors of heart failure after the fourth day included the same demographic predictors in addition to a history of hypertension, male sex, increased peak creatine phosphokinase level and heart rate, and decrease in left ventricular ejection fraction. In-hospital death occurred in 5.3% compared with 1.4% (P =.012) in patients who did and did not have heart failure, respectively. The occurrence of heart failure during hospital admission also adversely affected the 18-month follow-up, with 14.9% deaths in the patients with heart failure and 6.4% in those without heart failure (P =.002).

CONCLUSION

Heart failure is frequently associated with acute myocardial infarction and occurs with a bimodal distribution and is associated with increased risk of death during hospitalization and during 18 months of follow-up. Predictors of early heart failure include previous medical conditions and age. The second peak occurrence can be predicted by similar characteristics in addition to increased peak creatine phosphokinase level, decreased left ventricular ejection fraction, and increased heart rate.

Cimetidine-associated optic neuropathy

Two cases of optic neuropathy associated with cimetidine therapy are reported. Recovery occurred in both after drug withdrawal. Rechallenge with the same agent totally reproduced the condition in the first case. Cimetidine exerts an unequivocal toxicity on the central and peripheral nervous systems. Since its introduction in 1976, it has been used in over 100 million patients, but only 3 cases of optic neuropathy have been reported as far as we know. Although the mechanism of toxicity is still unclear, cimetidine is a well-recognized zinc chelator, and zinc deficiency has been implicated in causing optic neuropathy. Hence, it can be concluded that cimetidine produced this toxicity through its mechanism of zinc chelation. However, close ophthalmic follow-up of such patients is unnecessary, but an unexplained visual deterioration should prompt immediate drug withdrawal.

Ventricular remodeling. Mechanisms and prevention

The changes that take place in the structure and form of the left ventricle have become closely related to increase in clinical events in patients with heart failure. These changes are included in the term remodeling and occur as a response to the initial loss of left ventricular muscle mass. The mechanisms that initiate and maintain this remodeling process have become of great importance since a variety of effective pharmacologic agents have become available. A more complete understanding of remodeling has the potential of preventing the progression of heart failure. This article considers the various aspects of left ventricular remodeling including the cardiomyocytes, the myocardial interstitium, the importance that apoptosis plays the remodeling process.

Histamine receptors in the skin melanophores of Indian bullfrog Rana tigerina

Histamine and 2-methyl histamine caused dose-dependent aggregation of the integumental melanophores of Rana tigerina both in vitro and in vivo. The aggregating effects were antagonised by mepyramine and metiamide, specific H1 and H2 receptor blockers, respectively. Compound 48/80 and EDTA augmented the melanin-aggregating effects of exogenously applied histamine and 2-methyl histamine in in vivo experiments. 4-Methyl histamine, a specific H2 receptor agonist, dispersed the frog melanophores in in vitro studies, the dispersing effects were blocked by metiamide.

Usefulness of exercise echocardiography in predicting cardiac events in an outpatient population

The prognostic value of exercise echocardiography in an outpatient population is not well defined. A total of 1,020 consecutive patients referred for exercise echocardiography in an ambulatory care setting were studied by reviewing their medical records and exercise echocardiographic data. Of these, 71 (7%) were excluded due to technically inadequate tests, leaving 949 patients who were included in the analysis. A positive exercise echocardiogram (EE) was defined as an appearance of a new wall motion abnormality or worsening of a baseline abnormality. Cardiac events, defined as myocardial infarction, coronary angioplasty, coronary bypass surgery, and death, were documented during a 12-month follow-up period. Cardiac events occurred in 17% of patients (26 of 152) with a positive exercise echocardiogram (EE) and in 2.5% (20 of 797) with a negative EE (p <0.001). The incidence of myocardial infarction (2.6% vs 0.4%, p <0.02), coronary angioplasty (7% vs 1%, p <0.001), and coronary bypass surgery (9% vs 1%, p <0.001) were higher in patients with a positive versus a negative EE. There was 1 death in the positive study group and none in the negative group. Significant independent variables (p <0.05) that predicted cardiac events included a positive exercise electrocardiogram, history of coronary angioplasty, nonspecific ST-T changes on the baseline electrocardiogram, double product <25,000, men, chest pain on exercise test, and a positive exercise electrocardiogram. On a stepwise logistic regression model, exercise echocardiography emerged as an independent predictor of future cardiac events in an outpatient population. This predictive value was enhanced in the presence of a positive exercise electrocardiogram compared with a negative exercise electrocardiogram (24.2% vs 7.9%, p <0.03). Our study suggests that exercise echocardiography is an independent predictor of future cardiac events in an outpatient population.

Abnormalities of cardiocytes in regions bordering fibrous scars of dogs with heart failure

Progressive deterioration of left ventricular function is a characteristic feature of the heart failure state and is often speculated to result from ongoing loss of viable myocytes. We previously showed that in dogs with chronic heart failure, cardiocyte death through apoptosis occurs in the border region of fibrous scars (old infarcts). In the present study we examined the structural integrity of cardiocytes in regions bordering fibrous scars using transmission electron microscopy. Morphometric studies were performed using left ventricular tissue obtained from ten dogs with chronic heart failure produced by intracoronary microembolizations. Mitochondrial number increased significantly with proximity to the scar, while mitochondrial size decreased leading to a gradual decrease in mitochondrial volume fraction. Severe injury to mitochondria was present in only 5% of organelles in myocytes far from the scar but increased markedly to 28-41% in myocytes adjacent to or incorporated within the scar. Similarly, severe myofibrillar abnormalities were present in only 3% of myocytes that were far from the scar but increased significantly to 12-73% in myocytes adjacent to or incorporated within the scar. These results indicate that in dogs with chronic heart failure, constituent myocytes of left ventricular regions bordering fibrous scars manifest heterogeneity in the extent of degeneration. The extent of degeneration is greatest in myocytes closest to the scar and least in myocytes far from the scar. We postulate that this wavefront of myocyte degeneration is a dynamic process that may lead to progressive expansion of the scar through loss of viable myocytes and ultimately may contribute, in part, to the progressive left ventricular dysfunction that characterizes the heart failure state.

Effect of histaminergic drugs on integumental melanophores of adult Bufo melanostictus

Histamine and 2-methyl histamine caused dose-dependent aggregation of melanophores in toad B. melanostictus. The effects were effectively antagonised by mepyramine, a specific H1 histamine receptor antagonist, and metiamide a specific H2 receptor antagonist. On the other, hand 4-methyl histamine, a specific H2 receptor agonist dispersed the melanophores. The results suggest that adult Bufo melanophores have H1 histamine receptors which mediate melanophore aggregation, however, dispersion of melanophores may be controlled by undifferentiated histamine receptors of H2 type.

Synthesis of Some Hydrazone Derivatives Structurally Related to the Insecticide Pymetrozine

Reaction of pyridine-3-carbaldehyde methylhydrazone with 1,1'-carbonylbis-1H-imidazole afforded (E)-1'-methyl-2'-(3"-pyridyl) methylidene ]-1H-imidazole-1-carbohydrazide (2). Reaction of (2) with ethylamine, ethanol, ethanethiol, hydrazine monohydrate and methoxyamine afforded the corresponding semicarbazide, carbazate, thiocarbazate, carbonohydrazide and 4-methoxysemicarbazide derivatives (3a-d,g). Reaction of (2) with methylhydrazine gave the carbonohydrazide derivative (3f) together with 2,4-dimethyl-6-(3'-pyridyl)-1,4,5,6-tetrahydro-1,2,4,5-tetrazin-3(2H)-one (4a). The preparation of (E)-3-[(3'-pyridyl) methylideneamino ]oxazolidin-2-one (5a) and (E)-3-[(3'-pyridyl) methylideneamino ]tetrahydro-2H-1,3-oxazin-2-one (5b) is described.

Abnormalities of contractile structures in viable myocytes of the failing heart

We examined the incidence and severity of abnormalities of contractile structures of residual viable cardiomyocytes in the left ventricular free wall, septum and right ventricular free wall of 10 dogs with chronic heart failure produced by multiple intracoronary microembolizations and in septal biopsies of 13 patients with chronic heart failure. The abnormalities were evaluated by transmission electron microscopy and classified as either (i) type-1, defined as complete interruption of myofibrils; (ii) type-2, defined as disconnection of end-sarcomeres from the intercalated disc; or (iii) type-3, sarcomere abnormalities defined as Z-bands irregularities and/or focal myofilament disarray. In the left ventricular free wall of dogs, type-1 abnormalities were present in 33 +/- 8% of myocytes, type-2 in 26 +/- 8%, and type-3 in 63 +/- 9%. The incidence of a type-3 abnormality but not type-1 or type-2 was greater in the left ventricular wall compared with the septum and right ventricular wall (P < 0.05). Among abnormal myocytes, 29 +/- 3% of myofibrils were interrupted, 18 +/- 4% of end-sarcomeres were disconnected from the intercalated disc and 12 +/- 2% of sarcomeres were abnormal. The severity of a type-1 but not type-2 or type-3 abnormalities was greater in the left ventricular wall compared with the septum and right ventricular wall. A similarly high incidence of abnormalities was observed in septal myocytes of patients. The results indicate that abnormalities of contractile structures are common among viable myocytes of the failing heart. The incidence of these abnormalities is sufficiently high to warrant serious consideration of their potential role in the progression of left ventricular dysfunction that characterizes the heart failure state.

Preparation of Cyclohexane-1,3-dione Herbicide Precursors by Birch Reduction of 3,5-Dimethoxyphenyl-Substituted Silane Derivatives

Birch reduction of the silane derivatives (3a-d), prepared from Grignard cross-coupling reactions, afforded the cyclohexane-1,3-dione derivatives (5a-d) after acid hydrolysis. Compounds (5a-d) are precursors to silicon-containing herbicides of the general structure (8).

Epidemiology of atrial fibrillation in patients hospitalized in a large hospital

The prevalence of atrial fibrillation varies widely depending on the population studied. To understand the incidence of atrial fibrillation and its significance in relation to other diseases, 3 years (1989 through 1991) of consecutive hospital discharges from the neurology and internal medicine services at Henry Ford Hospital were studied. Of the 26,964 patients who qualified for analysis, 1346 (5%) had atrial fibrillation as 1 of their 5 recorded discharge diagnoses. Comparing the group without atrial fibrillation to those with atrial fibrillation, there were 51% males in both groups (p = 0.88). African-Americans comprised 33% of the patients with atrial fibrillation and 50% of the patients without atrial fibrillation (p < 0.001). The average age of those with atrial fibrillation was 72 +/- 13 years, and 58 +/- 18 years for those without atrial fibrillation (p < 0.001). Length of hospital stay was 9.6 +/- 8.6 days with atrial fibrillation and 7.6 +/- 9.2 days for those without atrial fibrillation (p < 0.001). After adjusting for the effects of age, significant positive associations were noted in those patients with atrial fibrillation whose co-existing condition was either stroke, heart failure, myocardial infarction, hyperthyroidism, or mitral valve disease. There was also a significant negative relationship between hypertension and atrial fibrillation. The most common of the 5 discharge diagnoses observed in patients with atrial fibrillation was congestive heart failure (40%), followed by hypertension (23%) and ischemic heart disease (21%). The existence of a comorbid disease in patients with atrial fibrillation is important, as it can influence medical management and prognosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of histaminergic drugs on tail melanophores of tadpole, Bufo melanostictus

The H1 and H2 receptor agonist histamine caused a powerful aggregation of B. melanostictus tail melanophores, which was completely blocked by metiamide, a specific H2 receptor antagonist, while mepyramine an H1 receptor blocker partially blocked the aggregating response. The strong melanin aggregating effect of 4-methyl histamine a specific H2 receptor agonist and its complete blockade by metiamide further supports the conclusion that there exists a dominant population of H2 type of histamine receptors along with sparse population of H1 receptor on the tail melanophores of the toad, which mediate centripetal movement of melanin granules within the pigment cells leading to blanching of the animal.

Chromosomal aberration analysis in peripheral lymphocytes of radiation workers

Chromosomal aberration analyses were performed in two groups of radiation workers and in a group of healthy controls. Although the level of exposure was below the accepted annual limit of 50 mSv, the yields of chromosome fragments and of total aberrations were significantly higher in the radiation workers than in the controls. However, the frequencies of dicentric and ring chromosomes in the radiation workers were not significantly different from those in the controls.

Establishment of dose-response relationships between doses of Cs-137 gamma-rays and frequencies of micronuclei in human peripheral blood lymphocytes

It has been suggested that the yield of micronuclei in human peripheral blood lymphocytes could be used as a biological dosimeter in cases of radiation exposure. In the present study micronuclei were induced in lymphocytes by exposing human blood samples in vitro to various doses of Cs-137 gamma-rays. The blood samples were then cultivated using the cytokinesis block method. Coded programs were employed to establish the relationships between the frequencies of micronuclei and various doses of gamma-rays. The best fit was obtained by the linear-quadratic model, Y = c + aD + bd2, where Y is the yield of micronuclei, D is the dose in Gy and c, a, b, are constants. It seems there is a correlation between the yields of MN in mononuclear cells and the corresponding doses of radiation. Therefore an attempt was made to include these MN in the calculation of the dose-response relationship.

[Changes in blood flow of the pulmonary artery valve studied by Doppler echocardiography in patients with pulmonary hypertension]

Blood flow in the vicinity of the pulmonary-arterial valve was examined in 20 normal subjects and 42 patients with pulmonary hypertension. Four major types were identified in the flow spectrum. Six flow classes were further identified on the basis of their combinations in the same patients. These classes were correlated with a number of hemodynamic parameters. They were shown to be related to systolic pulmonary-arterial blood pressure and total vascular resistance, but unrelated to diastolic and mean blood pressure in the pulmonary artery. There was no correlation with the cardiac cycle duration, ejection time, and cardiac output either, although the latter parameters differed significantly between normal subjects and patients with pulmonary hypertension. The classes identified permit a semiquantitative assessment of systolic blood pressure in the pulmonary artery and total peripheral resistance.