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Biomedical subjects

J M Hopkins

Publications and source records attributed to J M Hopkins.

At least 37 records · Page 2Linked to original sources
PubMed1986

The social behavior of autistic children with younger and same-age nonhandicapped peers.

Results of a study observing autistic children's interactions with nonhandicapped and autistic peers are reported. Six 8- to 12-year-old autistic children played in dyads with younger, normally developing kindergarten children and with nonhandicapped peers matched on chronological age for 10 15-minute sessions spaced over 3 weeks and then with a playmate of the alternate age for another 10 sessions. After intervention, all subjects showed gains in proximity, orientation, and responsiveness when playing with nonhandicapped peers and with autistic classmates. Same-age nonhandicapped playmates initiated more frequently than did younger nonhandicapped playmates and were better able to modify their initiations in ways that increased the likelihood of response from the autistic children.

Age Factors↗
PubMed1986

Laminin supports neurite outgrowth from explants of axotomized adult rat retinal neurons.

The influence of laminin on neurite outgrowth from explants of adult rat retina and its distribution in normal and lesioned rat optic nerves were examined. Neurite outgrowth required the presence of laminin in the substratum, and as with a goldfish retinal explant system, was markedly stimulated by prior axotomy. Except for blood vessels and the nerve sheath, normal rat optic nerve was devoid of laminin immunoreactivity. Unlike results seen in the goldfish optic nerve, injury to the rat optic nerve induced no observable increase in laminin content or change in its distribution. The differences in the in vivo regenerative capacities of these two species may in part be related to the differences in their abilities to provide a proper substratum for axon regrowth.

Animals↗
PubMed1985

Laminin and optic nerve regeneration in the goldfish.

Previous work from our laboratory had shown that goldfish retinal fragments explanted onto a polylysine substratum 1 to 2 weeks following optic nerve crush exhibit a striking clockwise pattern of neuritic outgrowth. In the present study, however, when the basal lamina component laminin was used as a substratum, neurites grew out as uncurved spokes, were less fasciculated, and had an increased rate of elongation. When laminin was combined with polylysine in the substratum, the degree of fasciculation and rate of elongation were similar to those seen on laminin alone, whereas the tendency for clockwise outgrowth was even more pronounced than that observed with polylysine alone. These results suggest that regenerating neurites have an affinity for laminin. Using an antibody to murine Engelbreth-Holm-Swarm sarcoma laminin, which cross-reacted with basal lamina in goldfish tissue sections, we studied the histochemical distribution of laminin in the goldfish visual system. Immunoperoxidase staining for laminin showed a characteristic scalloped pattern of staining in cross-sections of optic nerve bundles. Following optic nerve crush, the reaction product became much more diffuse and intense, especially distal to the crush site. When the retinal ganglion cell bodies were eliminated by removing the eye, the degenerating optic nerve stump still showed the intensive staining. We interpret these results to indicate that optic nerve glia are responsible in large part for the formation of laminin. Taken together, these in vivo and in vitro findings suggest that laminin plays a role in nerve regeneration in the goldfish central nervous system.

Animals↗
PubMed1984

Assessment of right ventricular function using two-dimensional echocardiography.

With the use of two-dimensional echocardiography (2DE), we analyzed apical and subcostal four-chamber views for evaluation of right ventricular (RV) function in 30 individuals as compared to RV ejection fraction (RVEF) obtained by radionuclide angiography. In addition to previously reported parameters of changes in areas and chords, a new simple measurement of tricuspid annular excursion was correlated with RVEF. A close correlation was noted between tricuspid annular plane systolic excursion (TAPSE) and RVEF (r = 0.92). The RV end-diastolic area (RVEDA) and percentage of systolic change in area in the apical four-chamber view also showed close correlation with RVEF (r = -0.76 and 0.81); however, the entire RV endocardium could only be traced in about half of our patients. The end-diastolic transverse chord length and the percentage of systolic change in chord length in the apical view showed a poor correlation with RVEF. The correlation between RVEF and both areas and chords measured in the subcostal view was poor. It is concluded that the measurement of TAPSE offers a simple echocardiographic parameter which reflects RVEF. This measurement is not dependent on either geometric assumptions or traceable endocardial edges. When the endocardial outlines could be traced, the apical four-chamber view was superior to the subcostal view in assessment of RV function.

Adult↗
PubMed1984

A neurofibrillar method stains solitary (primary) cilia in the mammalian retina: their distribution and age-related changes.

Richardson's reduced silver method, developed for the staining of autonomic nerve fibres in the mammalian intestine, is shown consistently to stain solitary (primary) cilia and diplosomes of the cells of the retinae of cats and rabbits. The cilia comprise a centriole, a basal body and an axoneme with a 9 + 0 complement of microtubules. Probably all retinal cells possess a cilium during their development but, contrary to previous reports, not all retain the axoneme after birth. Axonemes are absent from horizontal, bipolar, microglia, Müllerian, and probably some other glial, cells; all of which showed paired centrioles (diplosomes) after staining. Photoreceptor, amacrine, interplexiform, displaced amacrine and ganglion cells have each one cilium. These differences between cell types persist, without significant change, in the retina of adult rabbits up to the age of 2 years, and in the cat up to 5 years. The alpha-type ganglion cells of the cat are an exception. In 4 to 8-week-old kittens they are all ciliated, like other types of ganglion cells. But by two years about 30% of central area alpha-cells lack an axoneme. Individual cells may have only diplosomes, unusual dispositions of the centrioles in the perikaryal cytoplasm, or even show complete loss of the whole ciliary apparatus. By 5 years of age the proportion of those alpha-cells showing unusual arrangements has increased to approximately 70%, while less than 5% of the other types of ganglion cells are so affected. Cilia of peripheral alpha-cells change at a different rate and by 5 years of age are approximately like the 2-year-old central area population.

Aging↗
PubMed1983

Structural similarities and differences amongst neurofilaments.

Neurofilaments purified from cat, ox, Loligo and Myxicola nerve fibres are composed of different numbers of polypeptides with different molecular weights. Mammalian neurofilaments also differ from those of marine invertebrates by being about 20% larger in diameter. Despite the differences, X-ray diffraction patterns from all the neurofilaments indicate a common alpha-helical content with alpha-helices arranged in coiled-coils. The patterns from Myxicola neurofilaments also indicate a long-range periodicity along the length of these filaments which is of the order of 25.2 nm.

Animals↗
PubMed1983

Chronic effects of myocardial infarction on right ventricular function: a noninvasive assessment.

To assess the chronic effects of myocardial infarction on right ventricular function, 48 subjects were studied utilizing radionuclide angiography and two-dimensional echocardiography. Ten were normal subjects (group I), 11 had previous inferior wall myocardial infarction (group II), 10 had previous anteroseptal infarction (group III), 11 had combined anteroseptal and inferior infarction (group IV) and 6 had extensive anterolateral infarction (group V). The mean (+/- standard deviation) left ventricular ejection fraction was 0.66 +/- 0.03 in group I, 0.58 +/- 0.02 in group II, 0.52 +/- 0.02 in group III, 0.33 +/- 0.03 in group IV and 0.33 +/- 0.01 in group V. No systematic correlation between left and right ventricular ejection fraction was observed among the groups. The mean right ventricular ejection fraction was significantly reduced in the presence of inferior myocardial infarction (0.30 +/- 0.03 in group II and 0.29 +/- 0.03 in group IV compared with 0.43 +/- 0.02 in group I [p less than 0.001]). The group II and IV patients also had increased (p less than 0.001) right ventricular end-diastolic area and decreased (p less than 0.001) right ventricular free wall motion by two-dimensional echocardiography. In the presence of anteroseptal infarction (group III), right ventricular free wall motion was increased (p less than 0.05) compared with normal subjects (group I). Thus, the effects of prior myocardial infarction on right ventricular function depend more on the location of infarction than on the extent of left ventricular dysfunction. Inferior infarction was commonly associated with reduced right ventricular ejection fraction and increased right ventricular end-diastolic area. The right ventricular free wall excursion was increased in the presence of anteroseptal infarction, suggested loss of contribution of interventricular septal contraction to right ventricular ejection.

Adult↗
PubMed1982

Patterns of exercise response in patients with severe left ventricular dysfunction: radionuclide ejection fraction and hemodynamic cardiac performance evaluations.

To evaluate the exercise response of the severely diseased left ventricle, 13 patients with chronic congestive cardiomyopathy with mean resting ejection fraction (EF) of 18.8 +/- 9.6% underwent maximal supine bicycle exercise with hemodynamic and radionuclide monitoring. Two patterns of exercise response were noted. Group I (n = 7) was characterized by significant (p less than 0.001) increases in stroke work index (SWI) (+52%), stroke volume index (SVI) (+34%), mean arterial pressure (AP) (+23%), and cardiac index (CI) (+119%) and by a decrease in systemic vascular resistance (SVR) (-45% p less than 0.001). In group II (n = 6) there were no significant changes in SWI (-15%), AP (+11%), and SVR (-17%)(; SVI decreased significantly (-14%, p less than 0.05), and the increase in CI, although significant (+27%, p less than 0.01), did not achieve the level of Group I. EF did not change with exercise in either group. There were no significant differences at rest in any of the above variables, and the pulmonary capillary wedge pressures at maximal exercise were similar. We conclude that there are two patterns of exercise response in patients with severe congestive heart failure (CHF) and that these patterns may have important therapeutic and prognostic implications.

Adult↗
PubMed1982

Reproducibility of equilibrium radionuclide ventriculography in patients with coronary artery disease: response of left ventricular ejection fraction and regional wall motion to supine bicycle exercise.

To evaluate the reproducibility of ejection fraction (EF) and regional wall motion (RWM) analyses by rest and exercise equilibrium radionuclide ventriculography (RNV) in the presence of coronary artery disease (CAD), 18 patients underwent two maximum, multistage supine bicycle exercise studies separated by an interval of 2 weeks. There were no significant differences in EF between the two studies, both at rest (56.0 +/- 13.8% vs 58.2 +/- 11.7%, p = NS) and with exercise (51.1 +/- 17.6% vs 54.3 +/- 17.6%, p = NS) and a highly significant correlation was shown between the two groups of values (rest r = 0.90, exercise r = 0.93, p less than 0.001). There was no significant difference in the change from rest to exercise (-4.9 +/- 12.0% vs -3.8 +/- 11.5%, p = NS) between the two studies and the correlation was highly significant (r = 0.69, p less than 0.01). The interstudy variabilities were 2.2 +/- 6.1% and 1.2 +/- 7.3% for rest and exercise, respectively, and 2.0 +/- 9.2% for the change from rest to exercise. Ninety-four percent of both rest and exercise regions had similar RWM. Eighty-one percent of the abnormally contracting regions were common to both exercise studies. Utilizing conventional criteria for the diagnosis of CAD, 11 patients had abnormal EF response and nine had abnormal RWM response to exercise on both studies. Combining EF and RWM criteria resulted in the diagnosis of CAD in 15 patients in both studies. We conclude that: (1) there were no significant differences in rest and exercise radionuclide EF and RWM between two supine bicycle exercise studies performed 2 weeks apart in patients with stable CAD and there were significant correlations between the two studies; (2) despite these correlations, the interstudy variabilities emphasize the need for the inclusion of reproducibility studies in all evaluations of interventions by exercise radionuclide ventriculography; and (3) the variations in EF and RWM response to exercise result in lack of uniformity between the two studies regarding the diagnosis of CAD based on conventional RNV criteria.

Adult↗
PubMed1982

ATPase activities of human retina and pigment epithelium-choroid.

The Mg2+-, the Na+-K+-, and the HCO3--stimulated ATPase activities have been measured in the retina and pigment epithelium of postmortem human donor eyes. Activities were measured between 24 and 72 hr after death, following storage of the eyes in moistened chambers kept in a refrigerator. There appeared to be no significant differences in the ATPase activities between the 24 and 72 hr tissues. The human retina demonstrated both Mg2+- and Na+-K+-stimulated ATPase activity, but no HCO3+-stimulated ATPase activity, but not HCO3+-stimulated ATPase activity. The Na+-K+ ATPase activity was 1.54 mumol Pi/hr/mg protein, which amounted to 37% of the total ATP hydrolysis of the retina. The pigment epithelium-choroid showed significant Mg2+-, Na+-K+-, and HCO3--stimulated ATPase activities, with the stimulation caused by HCO3- about 25% greater than the effect due to Na+-K+, 0.64 vs. 0.51 mumol Pi/hr/mg protein. These findings in human retina and pigment epithelium-choroid show that certain metabolic processes continue to operate for several days after death.

Adenosine Triphosphatases↗
PubMed1981

Exercise-induced regional wall motion abnormalities on radionuclide angiography. Lack of reliability for detection of coronary artery disease in the presence of valvular heart disease.

Exercise-induced regional wall motion abnormalities on radionuclide angiography have been thought to be a reliable indicator of coronary artery disease. To evaluate their reliability, particularly in patients with valvular heart disease, exercise radionuclide angiography was performed in 12 normal subjects, 35 patients with coronary artery disease and 19 patients with valvular heart disease and normal coronary arteries. Exercise-induced regional wall motion abnormalities were found in none of the normal subjects, 63 percent of the patients with coronary artery disease and 42 percent of those with valvular heart disease and were predominantly inferoapical in location in the group with valvular heart disease. We conclude that exercise-induced regional wall motion abnormalities are not reliable for the detection of coronary artery disease in patients with valvular heart disease.

Adult↗
PubMed1981

Reverse redistribution: worsening of thallium-201 myocardial images from exercise to redistribution.

Reverse redistribution (RR) i.e., worsening of images from exercise to redistribution, was noted in 21 (7%) of 300 consecutive thallium-201 (201TI) exercise and redistribution myocardial imaging studies. In 13, there were reversible defects consistent with ischemia in addition to redistribution defects. Twenty RR defects were noted in 15 patients who underwent cardiac catheterization; 9 had triple, 4 had double and 2 had single vessel coronary artery disease. Seventeen (85%) of the RR defects were in the distribution of severely diseased vessels; 8 with 100% occlusion and 9 with 90-99% stenosis. The remainder were associated with 50-60% stenoses. Ten RR areas (50%) were supplied by collateral vessels and 3 (15%) by bypass grafts. Fourteen of the 18 (78%) areas studied with left ventriculography were associated with abnormally contracting segments. These results suggest that RR is a marker for significant coronary artery disease.

Cardiac Catheterization↗
PubMed1981

Biplanar cardiac blood-pool tomography.

Dynamic transverse axial wall tomograms of the left ventricle (LV) are reconstructed by a new technique from anterior and LAO views acquired with a conventional scintillation camera imaging the distribution of in-vivo Tc-99m-labeled red blood cells. By confining reconstruction to the singular contiguous uniform concentration of activity in the LV, the requisite angular samplings for a given level of accuracy are substantially reduced in this restricted form of emission computed tomography (ECT). Static phantom studies using a series of volumes having various cross-sectional dimensions demonstrate tomographic edge reconstruction with less than or equal to 12% rms radial error. The dynamic cardiac ECT is demonstrated in a series of representative patient studies by reconstruction of wall tomograms in the end-diastolic and end-systolic phases of the 28-frame cardiac cycle. In contrast to the conventional dual multiframe projection views, the motion tomograms derived from the reconstructions clearly show the complete three-dimensional perspective of wall displacement.

Heart↗
PubMed1980

Cigarette smoke-induced DNA damage and lung cancer risks.

Epidemiological studies have firmly established that cigarette smoking causes almost all cases of anaplastic and squamous cell bronchial carcinomas. It is equally well known, however, that many smokers do not develop lung cancer and, although the amount of tobacco smoked is undoubtedly, the dominant risk factor, it seems possible that other factors may also be involved. There is increasing evidence to support Boveri's old hypothesis that somatic mutation is an important event in the development of cancer and we have recently shown that cigarette smoke condensate (CSC) produces many dose-related lesions in the cellular DNA of cultured human lymphocytes as measured by sister chromatid exchange (SCE) induction. Cytogenetic studies had previously shown an increase in chromosomal aberrations in blood lymphocytes of heavy smokers relative to non-smokers, but little or no increase in SCEs. We have now measured basal and CSC-induced SCE rates in lymphocytes from different individuals and report that smokers have higher rates than non-smokers and that smokers with untreated lung cancer have consistently higher rates than their matched heavy smoking controls. These results are in keeping with the somatic mutational hypothesis and the epidemiological evidence, but also raise questions related to difficulties in smoking dosimetry and to possible variation among different individuals' responses to a common insult.

Carcinoma, Squamous Cell↗
PubMed1980

Studies on the concentration and intracellular localization of iron proteins in liver biopsy specimens from patients with iron overload with special reference to their role in lysosomal disruption.

Liver biopsies were collected from control subjects and patients with iron overload due to either primary or secondary haemochromatosis. They were analysed for iron proteins by cation exchange chromatography and flameless atomic absorption spectrophotometry. In control tissue the transferrin fraction contains 25%, ferritin 50% and haemprotein and haemosiderin 10--15% each, of the total iron. In iron overloaded tissue the ferritin and haemosiderin iron increases approximately 10- and 100-fold, respectively, compared with control tissue. There was a close positive correlation between enhanced lysosomal fragility as determined by measurements of latent N-acetyl-beta-glucosaminidase and haemosiderin content of the tissue; it is suggested that the haemosiderin is responsible for the lysosomal disruption and hence the tissue damage in iron overload. Studies were performed on the intracellular localization of ferritin and of total iron in biopsy extracts from control subjects and from patients with iron overload. In control tissue, ferritin contains most of the iron and is apparently free in the cytosol. In iron overload, ferritin is the major iron protein in the post-nuclear supernatant sedimenting into the gradient as the free protein. There are, however, significant amounts of immunoreactive ferritin deeper in the gradients but this cannot be assigned to any particular subcellular organelle. The extreme fragility of lysosomes in iron overloaded human tissue makes isolation of these organelles for detailed biochemical analysis extremely difficult.

Acetylglucosaminidase↗