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Biomedical subjects

M D Miller

Publications and source records attributed to M D Miller.

At least 217 records · Page 12Linked to original sources
PubMed1978

The physical working capacity of healthy black children.

The exercise performance of 170 black boys and girls, 7 to 14 years of age, was evaluated on a mechanically braked bicycle ergometer. The protocol is simple to perform in the hospital or in the field with normal children or children with heart or pulmonary disease. The results of the physical working capacity at a heart rate of 170 beats per minute (PWC170), a submaximal workload, are comparable to values previously recorded in California children. For a given body surface area, boys and girls younger than 10 years of age had similar PWC170 but boys 11 years and older had a greater capacity than girls of similar age or body surface area. There was a significant correlation between PWC170 and total work performed for boys (r = .81) and girls (r = .69).

Adolescent↗
PubMed1978

Blood pressure response to isometric and dynamic exercise in healthy black children.

One hundred seventy healthy black boys and girls (76 boys and 94 girls) had their systolic blood pressure (BP) determined at rest, during submaximum and maximum dynamic exercise, and in response to isometric exercise. Differences in BP between boys and girls were not significant. Blood pressure response to both dynamic and isometric exercise correlated with age and body surface area. Differences between resting BP and the BP during isometric exercise (BPiso), submaximum dynamic exercise (deltaBP170) and maximum dynamic exercise (deltaBPmax) for boys were: deltaBP150 18 +/- 9, deltaBP170 40 +/- 16 and deltaBPmax 55 +/- 17. Corresponding values for girls were: 16 +/- 8, 36 +/- 14 and 47 +/- 16. The higher the resting BP the less was the percentage change in BP to each stress.

Adolescent↗
PubMed1978

Exercise electrocardiography of health black children.

Exercise electrocardiography was performed on 170 healthy black children 7 to 14 years of age in order to determine the normal childhood electrocardiographic response to exercise. R-wave amplitude decreased from 27 +/- 8 (SD) to 22 +/- 8 mm (P less than .01) and the S-wave amplitude increased from 6.9 +/- 4.4 to 7.8 +/- 5 mm (P less than .01), indicating a shift of the mean QRS vector to the right at maximum exercise. J-point depression of 1.0 mm or greater was observed in 2.3% of children at maximum exercise, using the PR isoelectric line. ST-segment slope increased from 1.5 +/- 0.7 to 4.3 +/- 1.5 mV/sec at maximum. T-wave duration decreased with exercise and T-wave amplitude initially decreased with mild exercise but exceeded resting values at maximum exercise. No dysrhythmias were observed during or after the exercise study.

Adolescent↗
PubMed1978

Clinical use of transcatheter electrocoagulation.

Transcatheter electrocoagulation is an effective method of experimental vessel occlusion even in the presence of thrombocytopenia and heparinization. This technique was used to occlude 13 arteries in 3 patients. In vitro testing suggests that intra-arterial bipolar platinum electrodes may achieve the therapeutic objectives more rapidly and with less risk, but more investigative work is required.

Arteries↗
PubMed1978

Significant new observations on cervical spine trauma.

The results of a computer analysis of 399 patients with documented fractures and/or dislocations of the cervical spine are summarized. Vertebral arch fractures were present in half of all patients with radiographic evidence of cervical spine trauma. Two-thirds of the patients had two or more injuries. Isolated disk injuries were rare and, when present, were characterized by a vacuum sign. The dens fracture, with or without atlantoaxial dislocation, was rarely associated with injury elsewhere in the cervical spine. The study suggests that the routine five-film cervical spine examination is inadequate to detect the most common traumatic lesions. Thus vertebral arch views (pillar views) should be obtained if there is evidence to suggest hyperextension as the mechanism of injury. In addition, the study underscores the importance of aggressively searching for multiple abnormalities.

Axis, Cervical Vertebra↗
PubMed1978

Echocardiographic estimation of a left-to-right shunt in isolated ventricular septal defects.

35 infants and children with isolated ventricular septal defects (VSDs) had echocardiographic examination within 24 h of cardiac catheterization. Left atrial to aortic root (LA : Ao) ratio, left atrial internal dimension/meter square body surface area (LAID/m2) and left ventricular internal dimension in diastole/meter square body surface area (LVIDd/m2) were compared with the cardiac catheterization determined pulmonary-to-systemic flow (Qp : Qs) ratio. 35 children with normal cardiovascular findings served as controls. The LA : Ao ratio in the VSD group (1.38 +/- 0.13) was significantly higher than in the control group (1.01 +/- 0.05) (P less than 0.01). Similarly the LAID/m2 and LVIDd/m2 were significantly higher in the VSD group than in the control group (P less than 0.01). Additionally, echographic dimensions were increased in proportion to the elevation of Qp : Qs (r = 0.71--0.73). LA : Ao ratios higher than 1.4 : 1 were generally associated with Qp : Qs ratios greater than 2 : 1. All patients with Qp : Qs greater than 2 : 1 had LA : Ao ratios of 1.4 or higher. This study suggested that echocardiography is a useful noninvasive technique in estimating the Qp : Qs in patients with isolated VSDs, and may serve as an additional clinical parameter in the assessment of patients with VSDs.

Adolescent↗
PubMed1977

Structural convergence during protein evolution.

Several recent protein crystallographic structure determinations have demonstrated the existence of considerable tertiary structural similarity among proteins otherwise having little similarity in either amino acid sequence or biological function. In order to assess the possibility that such proteins may have arisen through processes of divergent evolution from a common ancestor, a graphical presentation is given which correlates the pattern of allowed single base substitutions defined by the genetic code with the associated changes in the structural properties of the encoded amino acids. The results show that while a large degree of structural conservation is evident due to codon synonomy, there is, in general, little tendency for the code to be structurally conservative in the majority of the cases where codon single-base changes result in amino acid substitutions. The possible consequences of this pattern of potential amino acid substitutions are discussed in relation to protein evolutionary processes.

Amino Acids↗
PubMed1977

Quantitative analysis of tubulin and microtubule compartments in isolated rat hepatocytes.

A combined morphometric and biochemical approach has been used to identify and quantitate microtubules and tubulin in isolated hepatocytes. The total soluble pool of microtubule protein was estimated by specific high affinity binding to radiolabeled colchicine. Scatchard analysis of the data identified two populations of binding sites: high affinity-low capacity sites resembling tubulin and low affinity-high capacity sites believed to represent nonspecific colchicine-binding sites. Data from these studies indicate that tubulin represents 1% of the soluble protein of the cell, that 9.0 X 10(-14) dimers of tubulin are present per microgram soluble hepatocyte protein, and that the average hepatocyte contains 3.1 X 10(7) tubulin dimers. Our calculations suggest that this amount of tubulin would form a microtubule 1.9 cm in length if totally assembled. However, stereological measurements indicate that the actual length of microtubules in the cytosolic compartment of the average hepatocyte is only 0.28 cm. Thus, these experiments suggest that only 15% of the available tubulin in hepatocytes of postabsorptive rats is assembled in the form of microtubules.

Animals↗
PubMed1976

Perinatal care of low-risk mothers and infants. Early discharge with home care.

A family-centered perinatal-care program featuring collaboration by nurse practitioners, obstetricians, pediatricians, and paramedical personnel was developed to enhance family participation and achieve a shorter but safe hospital stay. Discharge from the hospital was permitted as early as 12 hours after delivery. A perinatal nurse practitioner made daily home visits. The program's safety, feasibility, and acceptability to patients was studied by comparison of 44 patients so treated (study group) with 44 receiving traditional care (controls). Twenty-one study families, but no controls, went home within 24 hours. The study and control groups had no significant differences or trends in numbers of types of morbidity during hospitalization or the six-week post-partum period. The expense of the program is approximately equaled by hospital costs saved through early discharge. The results indicate that early discharge with home-care follow-up observation as described is safe, economically feasible, and well accepted by patients.

Adult↗