Comparison of interlaboratory results for blood lead with results from a definitive method

Results reported by 113 participants in the Blood Lead Proficiency Testing Program conducted by the Center for Disease Control were compared with those obtained by the National Bureau of Standards (NBS) with a definitive methods (mass spectroscopy-isotopic dilution) for blood lead analyses. Data were compiled from the results obtained for 12 whole-blood samples containing 1.5 g of disodium EDTA per liter. Twelve separate blood samples were obtained from cattle which had been given lead nitrate orally. Lead concentrations in the samples ranged from 0.628 to 4.93 mumol/L (130-1020 micrograms/L) as determined by NBS. The methods used by laboratories were classified according to six basic groups: anodic stripping voltametry; and atomic absorption spectroscopy in which either extraction, carbon rod, graphite furnace, tantalum strip, or Delves cup was used. For results obtained in each group a linear regression analyses of laboratory values was made on the basis of NBS values. In comparison to the definitive method, most field methods for blood lead tended to overestimate the lead concentration when the actual lead concentration was less than 1.96 mumol/L (400 micrograms/L) and to underestimate the lead concentration when the actual lead concentration was greater than 2.45 mumol/L (500 micrograms/L).

Comparison of interlaboratory results for blood lead with results from a definitive method

Results reported by 113 participants in the Blood Lead Proficiency Testing Program conducted by the Center for Disease Control were compared with those obtained by the National Bureau of Standards (NBS) with a definitive methods (mass spectroscopy-isotopic dilution) for blood lead analyses. Data were compiled from the results obtained for 12 whole-blood samples containing 1.5 g of disodium EDTA per liter. Twelve separate blood samples were obtained from cattle which had been given lead nitrate orally. Lead concentrations in the samples ranged from 0.628 to 4.93 mumol/L (130-1020 micrograms/L) as determined by NBS. The methods used by laboratories were classified according to six basic groups: anodic stripping voltametry; and atomic absorption spectroscopy in which either extraction, carbon rod, graphite furnace, tantalum strip, or Delves cup was used. For results obtained in each group a linear regression analyses of laboratory values was made on the basis of NBS values. In comparison to the definitive method, most field methods for blood lead tended to overestimate the lead concentration when the actual lead concentration was less than 1.96 mumol/L (400 micrograms/L) and to underestimate the lead concentration when the actual lead concentration was greater than 2.45 mumol/L (500 micrograms/L).

The time of origin of the mesencephalic trigeminal neurons in Xenopus

Time of origin of the mesencephalic trigeminal cells (MTC) in Xenopus 'has been studied with 3H-thymidine autoradiography. The first MTC's were formed at stage 20, and they continued to arise up to stage 58. The mitotic rate of MTC's was found to be ten per cent at any time from stages 20--50, with a slow decrease thereafter. MTC's in the tectum were distributed in a spatio-temporal manner. Cells generated earliest were located in the rostral pole of the tectum and were followed in caudomedial sequence by cells formed later. The generation times of MTC and the neurons of the sensory trigeminal ganglion (TGC) were strikingly dissimilar, indicating that they probably do not represent a common cell lineage, that is, the former may not arise from the mesencephalic neural crest. It is proposed that the majority of MTC's generated from stage 30 onward, derive through proliferative activity of precursor cells in the di-mesencephalic junction and in the tectal neuroepithelium.

Relation between cognitive and motor-oriented systems of visual position perception

Although subjects failed to detect a target displacement if it occurred near the time of a saccadic eye movement (a cognitive visual task), they were still able to point to the center of the target with an unseen pointer (a motor visual task). Pointing performance was not affected by detecting or failing to detect a stimulus displacement. The experiments demonstrate that some information that is available to a motor-oriented visual system is unavailable to the cognitive visual system, under conditions simulating normal perception.

Characteristics of the washout dead space

The dead space volume was reproducibly measured in normal and diseased lungs by analysis of an inert gas washout. This washout dead space was appreciably larger than that measured by the Fowler technique. In the patients, the washout dead space (VD(0)) formed 72% of the physiological dead space volume, while the Fowler (VD(F)) method accounted for only 50%. The VD(O) increased significantly with age in males, but not in females. VD(F) was not well related to age in this population. VD(O) and VD(F) did not relate to lung volume in these subjects. Although that portion of the dead space delivered in Phase I was significantly greater in males than in females, it was not responsible for the difference in dead space measured by the two techniques. This volume difference was found in that portion delivered late in the breath (Phase III). The nature of this volume is speculative, but may involve a parallel dead space that is measured in addition to the series dead space.

Industrial relations: taking the doctors' temperatures

Author considers the dilemma of the British Medical Association over its union status. Sanctioned by the Government but ignored by the union movement, will it become a dinosaur?

Plasma lipoprotein distributions in male and female runners

Recent studies have shown a consistent association between relatively low plasma concentrations of high-density lipoprotein (HDL) cholesterol and increased risk of coronary heart disease. A cross-sectional comparison was made of the distribution of plasma lipids and lipoproteins in groups of 41 male and 43 female long distance runners versus larger control groups matched for age and sex, randomly selected from northern California towns. The runners showed modestly lower total cholesterol concentrations, while their triglyceride levels were only 50% of control. HDL-cholesterol was higher in runners than controls (75 +/- 14 vs 56 +/- 14 mg/100 ml for women; 64 +/- 13 vs 43 +/- 10 for men), while low-density lipoprotein cholesterol was lower (113 +/- 33 vs 124 +/- 34 for women; 125 +/- 21 vs 139 +/- 32 for men). All differences were statistically significant (p less than 0.05), and only partially attributable to known factors other than high physical activity level. Since the runners were predominantly normotensive, relatively lean, and exclusively nonsmokers, they appear to constitute a remarkably favored group with respect to risk of cardiovascular disease.

Experimental infarct sizing using computer processing and a three-dimensional model

A method for noninvasive sizing of myocardial infarction, in which data from technetium-99m stannous pyrophosphate scintigrams and a three-dimensional model were used, was tested on experimental, acute anterior infarcts in dogs. The results indicate that the method does size experimental anterior infarcts accurately, but further testing will be necessary to assess the capabilities of the technique for sizing other types of infarcts.

Infarct sizing with technetium-99m stannous pyrophosphate scintigraphy in dogs and man; relationship between scintigraphic and praecordial mapping estimates of infarct size in patients

The present study was performed in order to evaluate the ability of technetium-99m stannous pyrophosphate (99mTc-PYP) myocardial scintigrams to size infarcts in experimental animals and man. In 10 dogs with proximal left anterior descending coronary artery occlusion and acute anterior myocardial infarcts, there was a significant correlation between scintigraphic infarct size and histological infarct weight (P less than 0.01). In 25 patients with acute anterior or anterolateral myocardial infarcts, there was a significant correlation between relatively large infarct size determined scintigraphically and the acute development of left ventricular failure. There was some overlap, however, in 99mTc-PYP scintigraphic infarct size between patients who did and did not develop left ventricular failure with infarction. Presumably this is explained by some patients having had earlier myocardial damage and thus developing left ventricular failure with relatively small new infarcts. There was also a statistically significant, but weak, correlation in patients between scintigraphic infarct size and precordial ST segment mapping including peak ST segment elevation (P less than 0.05) and the number of praecordial sites with ST segment elevation equal to or greater than 2 mm (P less than 0.01). The data suggest that 99mTc-PYP scintigrams and praecordial mapping measure some similar but some dissimilar aspects of infarct size in patients, and that 99mTc-PYP scintigraphy does size acute anterior and anterolateral infarcts in experimental animals and patients.

Reproducibility of thallium-201 myocardial imaging

Seventy-six thallium-201 myocardial perfusion studies were performed on twenty-five patients to assess their reproducibility and the effect ofvarying the level of exercise on the results of imaging. Each patient had a thallium-201 study at rest. Fourteen patients had studies on two occasions at maximum exercise, and twelve patients had studies both at light and at maximum exercise. Of 70 segments in the 14 patients assessed on each of two maximum exercise tests, 64 (91%) were reproducible. Only 53% (16/30) of the ischemic defects present at maximum exercise were seen in the light exercise study in the 12 patients assessed at two levels of exercise. Correlation of perfusion defects with arteriographically proven significant coronary stenosis was good for the left anterior descending and right coronary arteries, but not as good for circumflex artery disease. Thallium-201 myocardial imaging at maximum exercise is reproducible within acceptable limits, but careful attention to exercise technique is essential for valid comparative studies.

Children with terminal illness: a selected review

This brief review consdiers the psychiatric aspect of a child's dying from terminal illness. Much of the literature is largely theoretical, illustrated by case histories and clinical observations. Only recently has research been published based on empirical analyses of grief reactions in the child. There is no corresponding empirical research on the grief reactions of parents and siblings, or of the medical staff that cares for the terminally ill child. A review in this area points out the need for more integration of theoretical, clinical, and empirical work, including all aspects of a dying child's environment.

The distribution of plasma lipoproteins in middle-aged male runners

Stimulated by increasing evidence of an inverse relationship between plasma high-density lipoprotein cholesterol level and frequency of coronary heart disease, we determined concentrations of fasting plasma cholesterol, triglyceride, and lipoproteins in 41 very active men (running greater than 15 miles/wk for the previous year) 35-59 years of age (mean age, 47) and in a comparison group of men of similar age, randomly selected from three northern California communities. The runners had significantly (p less than 0.05) decreased mean plasma triglyceride (70 versus 146 mg/100 ml), total plasma cholesterol (200 versus 210 mg/100 ml), and low-density lipoprotein (LDL) cholesterol (125 versus 139 mg/100 ml) concentrations, and a higher mean level of high-density lipoprotein (HDL) cholesterol (64 versus 43 mg/100 ml) than the comparison group (n equals 147 for HDL and LDL; n equals 743 for total cholesterol and triglycerides). These very active men exhibited a plasma lipoprotein profile resembling that of younger women rather tan of sedentary, middle-aged men. This characteristic, and apparently advantageous, pattern could be only partially accounted for by differences in adiposity between runners and control subjects.

Clinical radiosotope investigations in hydrosyringomyelia and myelodysplasia

Radioisotope ventriculography was applied clinically in myelodysplastic hydromyelia in three groups of patients: two patients with normal ventricles, two with obstructive hydrocephalus, and 16 with myelodysplasia. In the myelodysplastic group, radioassay in one patient demonstrated flow of radioistope down the hydromyelic cavity. Twenty scintigraphic studies on 16 myelodysplastic patients showed hydromyelia was present in all patients with spontaneously compensated hydrocephalus but in none of those with functional ventricular shunts. This relation between the hydromyelia and disordered ventricular hydrodynamics supports the Gardner hypothesis of myelodysplasia. Radioisotope ventriculography appears a safe and useful method of diagnosing hydrosyringomyelia and evaluating treatment by means of ventricular decompression.

Radiosotope evaluation of experimental hydrosyringomyelia

Kaolin-induced hydrosyringomyelia in dogs has been investigated by radioisotope ventriculography using both cerebrospinal fluid radioassay and scintigraphy. The hydromyelic central canal can be differentiated from the spinal subarachnoid space by scintigraphy, Serial studies show that hydromyelia arises rapidly to decompress the associated hydrocephalus in surviving animals. Syringomyelia, after a delayed onset, originates from the enlarged central canal. Radioisotope ventriculography may be a useful clinical aid in the diagnosis of hydrosyringomyelia.

A mobile, mental-hospital-based team for geropsychiatric service in the community

At Norristown State Hospital a mobile Team of workers was organized to give personalized and preventive psychiatric, medical and social attention to distressed elderly people within the communities served by this large psychiatric institution. The Team's mobility permitted flexible approaches to problem-solving at the person's own home or other places of residence. Over its 8.5 years of existence the Team evaluated 1,438 elderly persons and acted in a consultant capacity to 77 nursing or retirement homes. Most of these clients were treated successfully within the community; only 222 required admission to the parent hospital during that time. Those treated in their own homes usually were able to maintain or improve the quality of their lives. The timely psychiatric, medical and social help often uncovered physical and social factors that previously had been overlooked.

The effect of anti-mu suppression of gammaM and gammaG on the production of gammaE

Newbonr mice were treated from the day of birth with either bovine gamma globulin or anti-mu chain sera. The latter was administered using a protocol known to produce suppression of gammaM, gammaG, and gammaA production. Subsequent immunization with ovalbumin (OA) in alum was attempted to see if suppression of gammaM, gammaG, and gammaA classes of antibody would also be accompanied by suppression of gammaE-producing capacity. gammaG and gammaM antibody to OA and mercaptoethanol-resistant (gammaG) antibody to OA were measured by passive hemagglutination; gammaG and gammaE anti-OA antibodies were measured by passive cutaneous anaphylaxis. Anti-mu suppression was achieved with significant reduction in gammaM and gammaG antibodies. gammaE antibodies were not affected, suggesting an ontogenetic development for gammaE-bearing lymphocytes independent of the previously described gammaM to gammaG to gammaA ontogenetic sequence.

Effects of physical activity on weight reduction in obese middle-aged women

Increased physical activity consisting of jog-walking 2.5 miles and 1 hr of calisthenics/week was the primary focus of a 17-week weight reduction program in 22 obese (X = 40% body fat) women ages 30 to 52, many of whom had failed at previous attempts to lose weight by dieting alone. Regular exercise was also increased substantially on an individual basis. Caloric restriction was self-determined and was generally moderate, accounting for about 60% of the total mean energy deficit. Initial and final evaluations included body composition by hydrostatic weighing, progressive multistage exercise testing, and plasma lipid and lipoprotein analyses. A mean relative body fat reduction of 5% (P less than or equal to 0.001) was achieved by a drop in fat body weight (X = 5.4 kg; P less than or equal to 0.001) which closely paralleled that of total body weight (X = 4.2 kg; P less than or equal to 0.001). Mean heart rates and systolic blood pressures at identical submaximal exercise intensities were significantly lower at the time of reevaluation. Mean plasma triglyceride and total cholesterol concentrations did not change significantly (P greater than 0.05). However, the high-density lipoprotein cholesterol/low-density lipoprotein cholesterol ratio increased significantly (P less than or equal to 0.05). Increased physical activity combined with moderate dieting is a feasible approach to weight reduction in middle-aged women.

Prediction of body composition in habitually active middle-aged men

In 45 physically active men (ages 35-67 yr) who underwent hydrostatic weighing to determine body composition, multiple regression equations were developed for the prediction of body density (D), lean body weight (LBW), fat body weight (FBW), and % fat using selected anthropometric measurements. The prediction accuracy for these parameters using several previously generated anthropometric regression equations was also determined. With equations developed from the present data a substantially higher correlation was obtained between measured and predicted LBW (r = 0.95) than between measured and predicted D (r = 0.85), FBW (r = 0.88), or % fat (r = 0.84). When previously developed equations were applied to the present sample, correlations between measured and predicted values were considerably lower (4-42%) than in the original studies; this reduction was least in the case of LBW. Analysis of previous data indicated that in selected populations total body weight can account for a relatively large fraction of the variance in LBW. LBW may be estimated quite accurately (r greater than or equal to 0.90) in physically active men with one of several regression equations which include total body weight as an independent variable.

Some patterns of B vitamin requirements among neritic marine bacteria

Twenty-four different patterns of single and multiple requirements for various B vitamins were demonstrated for 665 cultures of marine bacteria grown in a basal synthetic seawater medium enriched with phosphate, vitamin-free casamino acids, dextrose, and succinate. Among 114 thiamine-requiring isolates, 55 were unable to make the pyrimidine moiety, 19 required thiazole, 13 needed both thiazole and the pyrimidine moiety, while 27 organisms required thiamine or thiamine pyrophosphate for growth. Among 142 biotin requirers, 22 had to be supplied with biotin, 60 could use either biotin or biocytin, 54 were able to respond to either biotin, biocytin, or desthiobiotin. Only six cultures could not use biocytin, and required either biotin or desthiobiotin. Various responses of vitamin B12 requiring cultures indicated special types of specificity for cyanocobalamin and analogues of this vitamin. Computer-sorting at the 0.66 similarity coefficient breaking point arranged a group of 104 isolates into eight clusters. The isolates having biotin or thiamine requirements, single or in combination with other vitamin needs, appeared to be randomly scattered through the eight clusters.