Biomedical subjects
Publications and source records attributed to R Baker.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The thickness of left patellar articular cartilages after formalin fixation was studied in a series of autopsies on 82 subjects aged 25-96 years. For each specimen the minimal uncalcified cartilage thickness in a transverse patellar slab was determined separately for a 'lateral' segment and a 'central and medial' segment. In the women the cartilage from subjects more than 50 years old showed progressive thinning with increasing age. This was due to lesions causing disintegration of the tissue and not to matrix shrinkage. It had a strong potential to progress to full-thickness cartilage loss in the older women, and to give an appearance indistinguishable from osteoarthrosis as seen in surgical excision specimens. This progression towards patellofemoral osteoarthrosis in the elderly affects the female population generally, and not just a special subgroup; however, the incidence of clinical symptoms from this cause is not known. In men progressive thinning with age of patellar cartilage in subjects more than 50 years old was less severe, especially so in the case of the 'lateral' segment; a site of full-thickness uncalcified cartilage loss on the left patella at autopsy was seen only occasionally in the older men.
An 18-month controlled experiment was conducted into the effects of a token economy programme on the ward behaviour and symptoms of chronic schizophrenic patients. An experimental group received tokens dependent upon appropriate behaviour, while a matched control group on the same ward received every aspect of the ward programme similarly except that tokens were not dependent upon their behaviour. Regular assessment showed that both groups improved substantially in social withdrawal. Over twelve months of treatment the experimental group improved no more than the control group. There were no symptomatic changes. The conclusions were that token economy is a treatment affecting withdrawl and social behaviour rather than symptomatology, and that factors other than reinforcement by tokens were responsible for the main changes.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
1. Crude synaptosomal fractions (P2) from guinea-pig cerebral cortex were incubated in a Krebs-glucose medium containing labelled fatty acids and [3H]glucose. After the shortest incubation period (7.5 min) a high percentage (50-80%) of the total radioactive fatty acids was found in the P2 fractions. 2. After the incubation, the synaptosomal fractions were submitted to hypo-osmotic disruption and subsynaptosomal fractionation was carried out by using discontinuous-sucrose-gradient centrifugation. The specific radioactivities of phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine and phosphatidylinositol were determined in fractions D (synaptic vesicles), E (microsomal preparation) and H (disrupted synaptosomes), as were the specific activities of a number of marker enzymes and the distribution of acetylcholine. 3. By using [14C]oleate, [14C]arachidonate, [3H]palmitate and [3H]glucose, the order to specific radioactivities in fraction D was found to be: phosphatidylinositol greater than phosphatidylcholine greater than phosphatidylserine greater than phosphatidylethanolamine. 4. The specific radioactivities of phosphatidylcholine and phosphatidylethanolamine were always higher in fraction D than in fraction E. As fraction E had higher specific activities of several membrane marker enzymes, the enhanced labelling found in fraction D was considered to be localized in the synaptic vesicles. In this fraction, phosphatidylinositol made particularly large contributions to the total phospholipid labelling derived from [14C]arachidonate and [3H]glucose. 5. The similar labelling ratios of fatty acid/glucose in the phospholipids of fractions D and E, and the high specific radioactivities in the total phospholipid of the soluble fraction O, suggested intrasynaptosomal phospholipid transport.
The morphologic changes in 10 patients who were found to have squamous cell carcinoma of the lung before they became evident on chest x ray are discussed. It is suggested that these cases have a long preclinical course as invasive carcinomas that ranges from a microscopic focus of microinvasion (possibly originating from in situ carcinoma in submucosal gland epithelium) to a large concentric carcinoma which may have metastasized to regional lymph nodes. Although the duration of the in situ phase of squamous cell carcinoma of the bronchus in not known, it was evident that the expanse of in situ carcinoma frequently far exceeded that of the invasive carcinoma, and usually extended proximal to the invasive lesion. It is important that the extent of the in situ lesion is determined preoperatively. Finally, multifocal in situ (or invasive) carcinoma was found in at least two of the cases, either synchronously or metachronously.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
No evidence was found to support the existence of changes in the intrarenal flow pattern among the different areas or of a compensatory redistribution of microcirculation in the renal cortex under hypoxia induced by breathing 10 % oxygen. It seems that under these conditions the kidney is able to preserve its basic metabolism by diminishing its oxygen consumption.
Ultrastructural degeneration studies were carried out on the cat trochlear nucleus following lesion of the vestibulo-trochlear pathway in order to characterize the location and type of presynaptic endings involved in this pathway. Four types of boutons are found in the normal trochlear nucleus. Types I and II are large and demonstrate typical en passant profiles with small diameter synaptic vesicles (35 and 40 nm). These terminals are characterized by the absence of neurofilaments in the Type II endings. Types III and IV are smaller boutons, located more axondendritically, and contain larger diameter synaptic vesicles (45 nm). Type V terminals contain large, granulated vesicles and occur only rarely. Following the interruption of the ascending projection from the ipsilateral superior and medial vestibular nuclei by parasagittal medullary lesions, degeneration of Type II boutons was commonly encountered in the ipsilateral trochlear nucleus. Predominantly Type III degeneration was found in the contralateral trochlear nucleus. Electrical stimulation of the vestibular nerve showed that these lesions resulted in (1) a complete loss of inhibition in the ipsilateral trochlear nucleus and (2) a significant (75-90%) reduction in the contralateral excitatory pathway to the trochlear nucleus. Midline sagittal lesions in the floor of the fourth ventricle interrupting the decussating fiber projection from the bilateral medial vestibular nuclei resulted in selective degeneration of only Type III boutons in both trochlear nuclei. We conclude that inhibitory vestibular neurons eminating from the superior vestibular nucleus terminate on trochlear motoneurons with Type II boutons and excitatory vestibular neurons from the contralateral medial vestibular nucleus end on trochlear motoneurons with Type III boutons.
This experimental study was conducted to compare and contrast the cardiovascular effects of the drugs most commonly used to alleviate low-cardiac-output syndrome. Twenty-five adult mongrel dogs were infused with sodium pentobarbital (60 mg/min) until their cardiac output fell to 50+/-5% of the average control values determined by thermodilution technique prior to pentobarbital infusion. The dogs were then divided into six groups, and one of the following agents or combinations of agents was administered to each group: isoproterenol, glucagon, dopamine, dobutamine, levarterenol and phentolamine, or levarterenol and nitroprusside. All drugs, except for glucagon and the combination of levarterenol and nitroprusside, produced an increase in cardiac output above the nonfailure baseline values. However, this increase was accompanied by an undesirable, pronounced tachycardia except when levarterenol was used simultaneously with phentolamine. Both dopamine and the combined infusion of levarterenol and phentolamine proved the most effective in restoring systemic arterial pressure to near baseline values, and both were able to increase renal blood flow above the failure baseline values. While renal blood flow remained elevated with all dosages of levarterenol and phentolamine, it tended to decrease with larger doses of dopamine. These experiments demonstrate that there are major advantages in the use of simultaneously infused levarterenol and phentolamine for control of low-cardiac-output syndrome: increased cardiac output without elevated peripheral vascular resistance, restoration of systemic arterial pressure and consequent improved coronary flow, absence of tachycardia, and augmented renal blood flow.
A new type of self-retaining dry metal electrode for the electrocardiogram (ECG) is described which adheres to the skin by the application of negative pressure to an annulus surrounding the electrode, which is a bare silver. Data are presented for the factors which govern the adherence to the skin and the range of initial impedance and the values obtained at 2, 5, 10 and 20 minutes and with tap water under the electrodes. The initial impedance is usually high (0.18 to 10 megohms) and decreases progressively with time. Tap water placed under the electrodes dramatically reduces the initial range of impedance. Such electrodes, when used with an amplifier with an adequately high input impedance, can be used for recording electrocardiograms in a variety of situations.