Search PubMed⌕ Search

Biomedical subjects

H C Jones

Publications and source records attributed to H C Jones.

At least 91 records · Page 5Linked to original sources
PubMed1983

The impact of outpatient department and emergency room use on costs in the Texas Medicaid Program.

Medicaid claims data for a 35% random sample (n = 146,167) of persons receiving benefits from Aid to Families with Dependent Children, and who were eligible for Medicaid in Texas in 1980 are used to examine the impact of outpatient department (OPD)/emergency room (ER) care. Average cost is estimated for OPD/ER and private physician (MD) visits. Persons are also classified by primary source of care. Data on age, race, sex, residence, and months eligible in 1980 permitted prediction of statistically adjusted differences between OPD- and MD-oriented persons for number of ambulatory visits, probability of hospitalization, 1980 total costs, and both hospital episode institutional amount paid and length of stay. OPD/ER visits were found to be $23 more expensive than MD visits. OPD-oriented persons had fewer ambulatory visits, slightly more hospitalizations, greater total and episode costs, and longer lengths of stay than did MD-oriented persons. Potential cost savings are projected.

Adolescent↗
PubMed1982

The ultrastructure of the rhombencephalic posterior tela and adjacent tissues in an amphibian, Rana pipiens.

The posterior tela of the rhombencephalon, the overlying arachnoid mater, and the pial surface of the medulla were examined by transmission electron microscopy in the frog, Rana pipiens. The arachnoid mater and the pia mater have, with minor exceptions, similar ultrastructural characteristics to the same structures in mammals. The posterior tela, on the other hand, is an unusual membrane, the ependymal cells of which are modified to form numerous intercellular pores. These cells are pleomorphic (round, columnar or squamous) and have relatively few surface specialisations while their cytoplasm in electron-dense due to numerous microfilaments. Ependymal cells at the edges of pores are characterised by dense coils of basal lamina inserted into indentations of the lateral plasmalemma and, near the apical surface, by small specialised attachments to adjacent ependymal cells which are otherwise in a different plane.

Animals↗
PubMed1980

Circulation of marker substances in the cerebrospinal fluid of an amphibian, Rana pipiens.

Solutions of fluorescein-labelled dextran or Evans blue-albumin were infused into the lateral cerebral ventricle of Rana pipiens. The subsequent distribution in the cerebrospinal fluid (CSF) was investigated between 2 and 24 h after infusion by freezing and examination of the cut blocks of the head and vertebral column of the stage of a freezing microtome. These marker substances move out of the ventricles into the subarachnoid space at the caudal end of the fourth ventricle and spread rapidly along the subarachnoid space of the spinal cord. The spreading of marker substances is slower into the brain subarachnoid space, When the marker is infused into the subarachnoid space of the forebrain, it becomes distributed throughout the subarachnoid space of the brain and spinal cord but not in the ventricles. Partial clearance of markers from the ventricles takes place within 5 h and total clearance within 8 h. Clearance from the brain and cord subarachnoid space is somewhat slower and can only be detected in experiments lasting 10 h or more. Absorption of the markers from the CSF occurs via the intervertebral foramina of the spinal cord. Fluorescence microscopy of sections of the cord show that the fluorescence leaves the subarachnoid space at the point where the spinal nerves traverse the arachnoid membrane.

Animals↗
PubMed1980

Aflatoxigenic Potential for Aspergilli on sucrose substrates.

Sucrose concentrations of 3, 10, 20, and 30% in Czapek Dox broth served as the carbon source for growth, aflatoxin production, and sporulation for Aspergillus parasiticus NRRL 2999 and A. flavus NRRL 3557, 5862, and 5013. All cultures produced mycelial growth and sporulated in all sucrose concentrations during the 12-day growth period. The area of mycelial mat coverage per hour increased directly with increased sugar concentrations. The 20 and 30% sucrose concentrations inhibited mycelial growth for 5862. The 30% sucrose cultures of 3557 and 5862 failed to produce detectable levels of aflatoxins. All other isolates produced B1 and G1 in an approximately 4:1 ratio in all sucrose concentrations. Only 2999 was a substantial producer of aflatoxin in all 4 sucrose cultures, ranging from 72 to 96 micrograms/mL medium. A. flavus 5013 produced the most toxin, 144 and 126 micrograms/mL medium in the 10 and 20% sucrose cultures, respectively. The 10 and 20% sucrose cultures were most conducive to aflatoxin production. Since these sucrose levels correspond closely to the levels in many food and drink products, especially home-made products, care and attention should be taken to keep them free of aflatoxigenic spores. Extensive mycelial growth and sporulation, even in aflatoxigenic strains, do not necessarily result in comparably high aflatoxin levels. Routine extraction and quantitation procedures for aflatoxin were applicable and provided satisfactory results.

Aflatoxins↗
PubMed1979

The structure of the roof of the fourth ventricle in pigeon and chick brains by light and electron microscopy.

The hindbrains and meninges of the pigeon and chick have been examined by light and electron microscopy. Serial section histology of the skull with the brain and meninges intact has shown that the caudal end of the roof of the fourth ventricle consists of an extensive membranous pouch which projects caudally and dorsally into the subarachnoid space. Electron microscopy of selected areas of the membranous pouch in pigeon has shown it to consist of two components: ependymal cells and pial tissue. The membrane ependymal cells are squamous, adjacent cells being linked by intermediate junctions. At the junction with the surface of the medulla the ependymal cells are continuous with the ventricular ependyma, and at the choroid plexus they are continuous with the choroid plexus epithelium. These results are discussed in relation to the fluid spaces in and around the hindbrain.

Animals↗
PubMed1978

Continuity between the ventricular and subarachnoid cerebrospinal fluid in an amphibian, Rana pipiens.

Continuity between the ventricular and subarachnoid cerebrospinal fluid has been investigated in Rana pipiens. The structure of the posterior tela, a deficient membrane situated at the extreme caudal end of the roof of the fourth ventricle, has been studied using whole membrane mounts and by light microscopy of resin embedded tissue. The ependymal component consists of columnar and rounded cells which form a regular 'syncytium' enclosing round and oval fenestrations. Small fenestrations are covered on the subarachnoid side by elongated pial cells and thus do not give total continuity between the fourth ventricle and the subarachnoid space. Large fenestrations, on the other hand, are accompanied by equivalent pial fenestrations giving direct access between the fluid compartments. Towards the caudal end the fenestrations break up and the numbers of ependymal and pial cells decrease, the caudal end itself being characterised by a small remaining clump of ependyma and pia or of pia alone. Flow through the tela has been studied using fluorescein-labelled dextran placed in the intraventricular space. Infusion into the lateral ventricle and subsequent localisation by fluorescence microscopy shows the marker to be in the fourth ventricle, in the fenestrations of the posterior tela and in the subarachnoid space overlying the tela. Infusion of the marker followed by freezing and examination of the cut heads on a freezing microtome, shows fluorescence throughout the ventricular system, in the subarachnoid space adjacent to the posterior tela and also along the dorsal subarachnoid space of the spinal cord.

Animals↗
PubMed1978

Adaptation of the acoustic reflex.

The characteristics of acoustic reflex adaptation were studied in human subjects. Contralateral stapedial reflex measurements were made by monitoring changes in acoustic conductance and susceptance with a 220-Hz probe. The reflex activators included four tonal stimuli (500, 1000, 2000, and 4000 Hz) and broadband noise presented for 180 s at 96, 104, and 112 dB SPL. The data are presented as change in acoustic admittance and in percent of maximum admittance change. The static admittance of the ear was found to drift systematically toward lower admittance values in the absence of contralateral stimulation. All stimulus conditions demonstrated some reflex adaptation. The half-life and time of onset of adaptation were found to vary directly with intensity and inversely with frequency. The effects of stimulus parameters on the rates of reflex adaptation are discussed. A previously described exponential model of reflex adaptation provided a reasonable first approximation to the data.

Acoustic Stimulation↗
PubMed1976

The value of self-test items in tape--slide instruction.

Two tape-slide sequences in general pathology were used in an experiment to assess the value of self-test items and to determine whether it is better to intersperse the self-test items in the programme or place them all at the end of the sequence. The programmes were presented to a random sample of thirty-six students from a class of 149 in one of three forms: version 1, tape-slide programme without self-test items; version 2, tape-slide programme with self-test items interspersed between sections of the sequence; and version 3, tape-slide programme with all self-test items at the end of the sequence. Each student worked a pre-test before studying versions 1, 2 or 3 of a programme. A week later they worked through the post-test which was identical to the pre-test. At the same time they filled in a short attitude questionnaire on the teaching method. All students learned from the programmes. There was improvement in the post-test on the mean pre-test scores for all versions of both programmes. For one programme there was no significant difference between the mean post-test scores for students studying versions 1, 2 or 3, but for the other programme there was a significant difference between the versions. In this case the inclusion of self-test items was better for learning than no self-test items, and it was better if the self-test items were placed at the end of the sequence. A highly favourable attitude to the method is reported.

Audiovisual Aids↗
PubMed1973

Ultrastructural study of crossbands occurring in the stalks of Caulobacter crescentus.

An ultrastructural study of crossbands isolated from Caulobacter crescentus Sk1 418 stalks permitted a view of these structures in a plane other than the perpendicular view normally presented in the electron microscope. These crossbands were composed of concentrically arranged, alternating light and dark bands when stained with phosphotungstic acid. Evidence supports the hypothesis that crossbands appear to compose a structural barrier extending the width of the stalk and may function to support unit membrane extending the length of the stalk.

Bacteria↗
PubMed1969

Electron microscopic study of a slime layer.

Slime layers are being studied in our laboratories in an attempt to understand their functions in the control of pollution in natural streams. A method for fixing, staining, and embedding microorganisms in the intact slime has been developed. In this method, epoxy resin discs are placed in a holder and are introduced into a simulated stream. After various periods of time the discs are punched out of the holder into the fixative. The disc with the attached slime is fixed, stained (4% osmium tetroxide plus ruthenium red), dehydrated, and embedded in epoxy resin so that thin sections can be cut through the vertical plane of the slime mass. Such thin sections permit detailed examination of the attached layer, the surface-slime interface, the spatial relationships between cells in the vertical slime structure, and the strands of extracellular material between and around cells. No special attachment structures were noted as the cells appeared to be attached to the surface by extracellular material alone. This material was observed in strands and netlike forms between cells which are positioned 1 to 4 mum apart in the slime.

Bacteria↗