Biomedical subjects
Publications and source records attributed to A Hubbard.
The Functional Electrical Stimulation System consists of a host computer and up to 32 chips connected serially. Up to 256 different monophasic constant voltage (0 V-2.5 V), variable frequency (0 Hz-100 Hz in 2 Hz steps; 100 Hz-1700 Hz in 100 Hz steps), and adjustable duration (50 microseconds-200 ms in 50 microseconds steps) pulse trains can be continuously generated.
Immunocytochemical confocal laser scanning microscopy and ultrastructural analysis, including immunoelectron microscopy, reveals the distribution of structures in human term amniochorion similar in some respects to basement membranes but with unusually restricted dimensions. On the basis of their immunoreactivity, these trabecular structures, found on the fibroblast layer side of the spongy layer of human term amniochorion and adjacent reticular layer, have been shown to contain type IV collagen, laminin, and nidogen. The origin of these components may be from primitive epithelial structures which pumped fluid into the lakes that eventually coalesced to form the extraembryonic coelom separating the extraembryonic somatic mesoderm from the extraembryonic splanchnic mesoderm. Such a theory of their origin might link them with the mysterious 'cellular layer', a single-cell-thick layer of cells which is usually no longer present in fetal membranes at term. The similarity in composition but not in size of these structures to anchoring plaques for type VII collagen is possible support for the view that these structures are integrators of extracellular matrix polymeric proteins. The 'pseudobasement' membrane associated with the trophoblast layer, on investigation, appears to be typical by six criteria. 'Coiled' fibrous structures in the extracellular matrix of the spongy layer may aid adjustments under tension at this shear surface by a detachable 'Velcro' or 'two spring' fastening system. The coils are rich in fibronectin. The suggestion is made that the compact layer is a giant lamina reticularis associated with the amniotic epithelial basement membrane.
A two-mode model of the cochlea that uses active intermode feedback has been developed that quantitatively accounts for the motion of the basilar membrane in response to single tones and qualitatively accounts for cochlear emission phenomena. In contrast to existing single-mode models, this model amplifies the mechanical traveling wave in spatially localized cochlear regions where an approximate match occurs between the traveling-wave velocities of each of the two traveling-wave lines or modes.
Key cytoskeletal polypeptides of human fetal membranes have been localised at subcellular level using confocal and conventional indirect immunofluorescence microscopy. Correlation with electron microscope data has allowed us to examine how cellular compartments of this multilaminar tissue maintain their mechanical integrity until the time of membrane rupture at parturition. Evidence is presented for myofibroblastic characteristics of cells in both the fibroblast and reticular layers which may therefore have tension-generating, position-adjustment and wound-healing roles in the amniochorion. Desmin and vimentin are coexpressed in these cells, but a small localised population of cells in the fibroblast layer contains vimentin alone. An interaction of cytokeratin filaments with nuclei and desmosomes of amniotic epithelium in vivo is demonstrated, indicating that nuclei of cells of ectodermal origin are integrated into a mechanical structure extending throughout the tissue as a whole. Cells of the basal 1 or 2 layers of trophoblast have been shown to have a more extensive and better integrated cytoskeletal organisation than those overlying and forming the boundary with decidua. Structures within the trophoblast, identified previously as degenerate villi, contain cells with intermediate filaments with similar immunofluorescence properties to those of the neighbouring reticular layer and thus may represent papillae that prevent shearing at this interface.
Solutions of albumin, for injectable use in humans, are shown to contain the transition metals vanadium, copper, and iron. Variation in the concentration of these metal ions among products from six different manufacturers suggests that problems of metal contamination arise through manufacturing processes. Vanadium concentrations correlated with the loss of tryptophan residues in albumin, whereas copper concentrations correlated with loss of thiol groups and tryptophan residues. Incubation of vanadate and cupric salts with the thiol group-containing molecules cysteine and glutathione resulted in reduction of the metal ions to lower oxidation states. Reduced forms of vanadium and copper were able to transfer electrons to molecular oxygen and produce highly reactive and damaging intermediates of oxygen, such as the hydroxyl radical.
The purpose of this study was to establish guidelines for normal splenic size at different ages by using a simple and reproducible sonographic method. Two hundred thirty patients, from neonate to 20-year-old, had sonography because of abdominal and/or pelvic problems unrelated to the spleen. Findings on sonograms of the liver and kidneys were normal in all cases. Splenic size was measured by obtaining a coronal view that included the hilum, while the patient was breathing quietly. The greatest longitudinal distance between the dome of the spleen and the tip (splenic length) was measured and correlated with age, height, and weight. The following guidelines are proposed for the upper limit of normal splenic length based on this simple, easy to use, one-measurement technique: splenic length no greater than 6.0 cm at 3 months, 6.5 cm at 6 months, and 7.0 cm at 12 months, 8.0 cm at 2 years, 9.0 at 4 years, 9.5 cm at 6 years, 10.0 cm at 8 years, 11.0 cm at 10 years, 11.5 cm at 12 years, 12.0 cm at 15 years or older for girls, and 13.0 cm at 15 years or older for boys. Twenty-two patients with known abnormalities of the spleen were randomly selected and their splenic lengths compared with the proposed guidelines; in each case, the length of the spleen exceeded the upper limit of normal for that age. Normal values of a single measurement of the greatest longitudinal diameter of the spleen, from the dome to the tip measured at the hilum in the coronal plane, were obtained in patients from newborn to 20 years old.
Knowledge, attitudes, and practice patterns concerning cholesterol and heart disease were evaluated in a stratified, random sample of 206 registered nurses at a major academic medical center in New York City. Virtually all nurses were convinced of the importance of diet in reducing heart disease risk, and most (78%) agreed that nutrition counseling should be their responsibility. Although only 19% reported that they were currently counseling, many more felt prepared to counsel about diet or drug therapy (43%). Nurses who were likely to counsel were those working in general medicine, those who were certified nurse practitioners, those who knew their own blood cholesterol level, and those with higher knowledge scores. Level of overall knowledge was associated with the practice of counseling, an attitude that counseling should be a nurse's responsibility, and personal health behavior (knew own level), regardless of age or occupational or degree status. Despite their enthusiasm for heart disease prevention through diet modification, many nurses had substantial knowledge gaps, suggesting that nurses are currently not adequately prepared to counsel about diet and/or drug treatment for high blood cholesterol. Educational strategies and considerations in integrating an expanded role for nurses with those of physicians and dietitians are discussed.
Recent work suggests that an autosomal dominant gene for schizophrenia may be located on the 5q11-q13 region of chromosome 5 (refs 1 and 2): a report of schizophrenia associated with trisomy 5q11-q13 in two members of a family of Chinese origin prompted the discovery of linkage with markers p105-599Ha and p105-153Ra in five Icelandic and two English schizophrenic families. The strongest linkage was observed when the phenotype was broadly defined to include minor psychiatric diagnoses not traditionally considered part of the schizophrenia spectrum. By contrast, no evidence was found of linkage in a single multiplex Swedish schizophrenic pedigree. To determine whether these conflicting results arise from genetic and/or uncertainties in defining the schizophrenic phenotype, we examined fifteen Scottish schizophrenic families with restriction fragment length polymorphisms that span this region. We found no evidence for linkage, regardless of how broadly or narrowly the schizophrenic phenotype is defined, and conclude that a susceptibility locus, whose presence awaits confirmation, on the proximal portion of the long arm of chromosome 5 can be responsible for only a minority of cases of familial schizophrenia.
A multiinstitutional study of 39 esophageal injuries treated between 1982 and 1988 and a comprehensive review of the literature revealed an unacceptably high mortality rate of more than 20%. Results of the current study indicated that prompt diagnosis and aggressive surgical management of esophageal injuries could improve the outcome and lower the associated mortality. The clinical experience and literature review allowed us to elaborate caveats and principles that, if adhered to, should improve the outcome in esophageal injuries.
A diffuse B cell lymphoma was recognized at autopsy in an otherwise healthy 3 1/2-year-old girl with a three-month history of recurrent seizures. This lymphoma, treated only by debulking, was found at autopsy to have originated in the right cerebral hemisphere and to have metastasized throughout the brain, the leptomeninges around the brain stem and cerebellum, and the ventricular system. Unusual features in this lymphoma included tumoral calcifications associated with necrosis, tumoral cystic changes, polyclonal tumor cells, and meningeal metastases.
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This experiment addressed the question of whether reading comprehension and speed could be predicted by eye fixations. From a sample of university students who completed tests of reading comprehension and vocabulary, we selected a group of highly skilled readers and a group of less skilled readers. These two groups then read sentences as their eye movements were monitored, with fixation locations and durations recorded. A discriminant function analysis showed that fixation duration was a successful predictor of reading comprehension, but that the number of fixations, regressive fixations, reading speed, and vocabulary were not reliable predictors. A multiple regression analysis revealed that reading speed was predicted by the number of fixations, the average fixation duration, and the duration of the final fixation upon the sentence, but there was no relationship with reading ability. Highly skilled readers are those who can extract information efficiently, but are not necessarily those who have fast overall reading rates.
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