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Biomedical subjects

J A Beal

Publications and source records attributed to J A Beal.

At least 19 recordsLinked to original sources
PubMed1992

A study of catecholamine concentrations in selected renal segments of cats of different ages.

Renal concentrations of the catecholamine neurotransmitters norepinephrine (NE) and dopamine (DA) in 19 cats were measured by reverse-phase high pressure liquid chromatography (HPLC) with electrochemical detection. Animals of five different age groups (2-4, 6-8, 10-12 and 16-20 weeks and adult animals one year and older) were anesthetized and the kidneys were excised, sectioned into cortical, outer medullary and inner medullary segments, and processed for HPLC. There were no statistical differences in cortical NE concentrations between the 2-4 week and adult age groups, suggesting that peak noradrenergic nerve terminal density in the cortex is achieved at or before 2-4 weeks of age. NE concentration in the outer medulla and DA concentration in the cortex and outer medulla increased from the 2-4 to the 10-12 week age group but did not change significantly in the older animals. There were significant decreases in inner medullary NE and DA concentrations from the 10-12-week to the 16-20 week age group. The decrease in concentration of inner medullary catecholamines in the early postnatal period is consistent with the reported total loss of tyrosine hydroxylase- and dopamine beta hydroxylase-immunoreactive inner medullary nerve terminals at approximately 12 weeks of age.

Aging↗
PubMed1991

Neurogenesis of ascending supraspinal projection neurons: ipsi- versus contralateral projections.

The present study tests the hypothesis that contralaterally projecting supraspinal projection neurons (SPNs) are generated prior to ipsilaterally projecting SPNs. Neuronal time of origin was determined by injecting pregnant rats with tritiated thymidine on one of embryonic (E) days E12 through E15. In mature offspring of thymidine-treated dams, SPNs in the lumbar cord were retrogradely labelled with True Blue delivered at the site of a hemisection in spinal segment C3. Ipsi and contralaterally projecting SPNs in laminae I, VII and VIII and the lateral spinal nucleus, which are known to give rise to long sensory pathways, were generated simultaneously throughout their neurogenic period (E12-E14), while ipsilaterally projecting SPNs in lamina IV and the nucleus dorsalis, which give rise to short sensory pathways, completed neurogenesis one day later (E15). Results suggest that the projection target and its distance from the nerve cell body of origin are more consistent correlates of the duration of the neurogenic period than the course of the axon.

Animals↗
PubMed1991

Calcitonin gene-related peptide-immunoreactive nerves in the rat kidney.

Cryostat- and vibratome-cut rat kidney secretions were singly or doubly labeled to visualize immunoreactive calcitonin-gene-related peptide (CGRPI) and substance P (SPI). Rats were perfused with 2-4% paraformaldehyde + 0.15% picric acid then rinsed with buffer. Horseradish peroxidase (HRP) was used to visualize CGRP in vibratome sections, and combined HRP and fluorophore were used to visualize the two peptides simultaneously in cryostat sections. There is a complex, multilayered plexus of CGRP nerves on the renal pelvis and a less dense, single-layered plexus on the major branches of the renal artery and on interlobar arteries and veins. A few axons innervate finer branches of the arterial tree and other intrarenal structures. Results of double immunolabeling suggest that SPI axons comprise a subpopulation of the CGRP axon population in the rat kidney. There was no evidence for a separate population of SPI axons.

Animals↗
PubMed1991

Periodontics.

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Humans↗
PubMed1991

Patient demographic characteristics and housestaff performance in the care of patients with human immunodeficiency virus disease.

A retrospective review of the medical records of 45 patients with human immunodeficiency virus (HIV) disease was conducted in an Oklahoma internal medicine teaching clinic. Demographics of this patient population and house staff performance in the care of these patients was evaluated. The study population demographics were similar to national findings with the exception of lower documented homosexual/bisexual transmission among males and higher heterosexual transmission among females. Deficiencies in documentation were noted in the areas of route of acquisition, mental status, and functional level. In several instances patients who were candidates for zidovudine and/or Pneumocystis prophylaxis were not receiving these treatments. The quality of care could be enhanced through the use of HIV evaluation and treatment protocols as well as specially designed, HIV-specific medical records to improve data collection. These HIV-specific medical records can be found in the appendices.

Clinical Protocols↗
PubMed1991

Methodological issues in conducting research on parent-infant attachment.

The study of the parent's attachment to his or her infant has recently become a research topic of great interest to parent-child nursing practitioners. The parent-infant relationship has been examined using a variety of methodological approaches. Brazelton Neonatal Behavioral Assessment Scale demonstrations, home and laboratory observations, process recordings, videotape analyses, self-reported questionnaires, and developmental screening tools have all been used by researchers to measure the quality of this earliest form of human attachment. However, there are rising concerns as to the validity of attachment research in general, as well as methodological limitations in collecting data on parent-infant interactions. This article discusses issues of methodological concern in attachment research and makes suggestions to strengthen validity.

Adult↗
PubMed1991

Disclosure.

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Communication↗
PubMed1990

Transitory inner medullary nerve terminals in the cat kidney.

An indirect immunohistochemical method was used to visualize nerves immunoreactive for tyrosine hydroxylase (THI) and dopamine-beta-hydroxylase (DBHI) in kidney sections of cats 6 weeks and 2 and 3 months of age. THI and DBHI nerve terminals innervate the renal pelvis, interlobar veins and arterial tree including medullary vascular bundles of cats of each age studied. In kidneys of 6-week-old cats, THI and DBHI axons form elaborate plexuses that are distributed throughout much of the inner medulla, whereas some medullary axons appear to degenerate at 2 months and no inner medullary plexuses were visualized in 3-month-old cats. Transitory inner medullary nerves in the cat kidney may influence cellular development and play a role in salt and water balance.

Aging↗
PubMed1990

Nerve cell bodies in the dorsal funiculus of the rat spinal cord.

Nerve cell bodies located within the white matter of the dorsal funiculus (DF neurons) have been previously observed but not described in detail. The present study examines the morphology, ontogeny, and projection of DF neurons utilizing Fluoro-Gold as a retrograde tracer, alone, and in combination with tritiated thymidine autoradiography in the spinal cord of the rat. DF neurons were consistently labelled in spinal segments T13 through L2 following injections of Fluoro-Gold into the cerebellum. The cell bodies of DF neurons were small to medium in size, fusiform to multipolar in shape, and were located on the side ipsilateral to the injection site. Cell counts revealed approximately five labelled cells per millimeter along the longitudinal axis. An examination of neurogenesis using tritiated thymidine combined with Fluoro-Gold showed that DF neurons have relatively late birthdates as do other spinocerebellar neurons of the dorsal horn. Retrograde axon tracing studies in the spinal cord using Fluoro-Gold showed that DF neurons project rostrally via the ipsilateral lateral funiculus. The significance of the presence of nerve cells in the dorsal funiculus is unclear, but judging from their location, ontogeny, and projection, DF neurons are probably derived from the same pool of neurons as those in the Nucleus dorsalis.

Animals↗
PubMed1990

Neurons with asymmetrical dendritic arbors in the substantia gelatinosa of the rat spinal cord.

Two types of neurons were observed in the substantia gelatinosa (SG) of the rat spinal cord which exhibit wide variations in dendritic symmetry. As demonstrated with the Golgi technique, "islet" cells with short dendritic arbors and "type III stalk" cells display dendritic patterns which vary from a bipolar type arrangement with two dendritic arbors of nearly equal dimensions to a unipolar arrangement with a dendritic arbor which extends in only one direction. Examination of the morphology and dendritic development of these neurons shows that they are unique compared with other SG neurons in that they have short, longitudinal dendritic arbors which undergo maturation relatively late in the postnatal period. As is discussed, variations in dendritic symmetry are probably dependent on the location of the terminal fields of primary and/or other types of afferents which are formed earlier in development.

Animals↗
PubMed1990

Neurogenic period of ascending tract neurons in the upper lumbar spinal cord of the rat.

Although the neurogenic period for neurons in the lumbar spinal cord has been clearly established (Days 12 through 16 of gestation), it is not known when the neurogenesis of ascending tract neurons is completed within this period. The purpose of the present study was to determine the duration of the neurogenic period for projection neurons of the ascending tracts. To label neurons undergoing mitosis during this period, tritiated thymidine was administered to fetal rats on Embryonic (E) Days E13 through E16 of gestation. Ascending tract neurons of the lumbar cord were later (Postnatal Days 40-50) labeled in each animal with a retrograde tracer, Fluoro-Gold, applied at the site of a hemisection at spinal cord segment C3. Ascending tract neurons which were undergoing mitosis in the upper lumbar cord were double labeled, i.e., labeled with both tritiated thymidine and Fluoro-Gold. On Day E13, 89-92% of the ascending tract neurons were double labeled; on Day E14, 35-37%; and on Day E15, 1-4%. Results showed, then, that some ascending tract neurons were double labeled through Day E15 and were, therefore, proliferating in the final one-third of the neurogenic period. Ascending tract neurons proliferating on Day E15 were confined to laminae III, IV, V, and X and the nucleus dorsalis. Long tract neurons in the superficial dorsal horn (laminae I and II), on the other hand, were found to have completed neurogenesis on Day E14 of gestation. Results of the present study show that spinal neurogenesis of ascending projection neurons continues throughout most of the neurogenic period and does not completely follow the well-established ventral to dorsal gradient.

Animals↗
PubMed1990

A new rat spinal cord injury model: a ventral compression technique.

A new rat spinal cord injury model, which uses a modification of a DeBakey aortic aneurysm clamp to create the injury, is presented. The model produces a ventral persisting mass (bone and soft tissue) without the requirement of a prior decompressive operation (laminectomy). Modifications of the original technique have resulted in a nil surgical mortality rate. This technique has been applied to 138 animals. It has produced a consistent percentage of animals with complete myelopathies, as well as incomplete myelopathies and animals without apparent injury. The percent of baseline neurological function lost (change in degrees of the angle of tilt as measured by the inclined plane technique) in each group of surviving animals was 58, 36, and 9%, respectively. Sagittal postmortem sections confirmed mass lesions located ventral to the spinal cord. Histological sections confirmed neuronal loss consistent with the neurological findings.

Animals↗
PubMed1990

Dose-dependent effects of naloxone and methylprednisolone in the ventral compression model of spinal cord injury.

A study of the dose-response effects of naloxone and methylprednisolone after rat ventral spinal cord injury is presented. The spinal cord injury model used herein is unique in that it results in a ventral compression of the spinal cord without the need for a prior laminectomy. This allows for a close approximation of the human clinicopathological situation. There was a statistically significant positive effect on neurological outcome with a naloxone dose of 2.5 mg/kg, whereas higher and lower doses yielded little or no influence on outcome. Methylprednisolone was observed to offer similar results. These results, however, did not achieve statistical significance. The early administration of moderately high doses (45-60 mg/kg), however, offered the best results. The responses to the treatment regimens presented here offer hope for spinal cord injury victims. The observed dose-response relationships indicate that erroneous conclusions may arise from studies using inappropriate doses of narcotic antagonists, as well as other drugs.

Animals↗
PubMed1989

Identification of noradrenergic nerve terminals immunoreactive for neuropeptide Y and vasoactive intestinal peptide in the rat kidney.

Cryostat- and vibratome-cut sections of rat kidneys were singly or doubly labeled to visualize immunoreactive tyrosine hydroxylase (THI), dopamine beta-hydroxylase (DBHI), vasoactive intestinal peptide (VIPI), and neuropeptide Y (NPYI). Rats were perfusion fixed with 2-4% paraformaldehyde with or without 0.15% picric acid and rinsed in buffer for 18-48 hr. Single antigens were labeled with horseradish peroxidase in vibratome sections, whereas cryostat sections were used to label one antigen with peroxidase and another with a fluorophore in the same tissue section. A dense plexus of DBHI noradrenergic nerves innervates the renal arterial tree, and such nerves innervate the interlobar veins and renal calyx as well. Immunoreactive NPY is colocalized in most of these nerves, but some intrarenal noradrenergic nerves do not contain NPY but do contain VIP immunoreactivity. The distribution of NPYI nerves resembles that of DBHI nerves, whereas most perivascular noradrenergic nerves immunoreactive for VIP innervate selected arcuate and interlobular arteries. A small population of nonadrenergic, VIPI nerves innervates the renal calyx.

Animals↗
PubMed1989

Catecholamine-containing, dopamine-beta-hydroxylase-immunoreactive perivascular nerve specializations in the rat kidney.

Fluorescence histochemical visualization of catecholamines and immunolabeling of dopamine beta hydroxylase (DBH) were employed to study noradrenergic nerve terminals and perivascular nerve specializations in the rat kidney. Plexuses of catecholamine-containing and dopamine-beta-hydroxylase-immunoreactive nerves innervate the intrarenal arterial tree and larger intrarenal veins. Some perivascular nerve bundles have specialized segments composed of clusters of axonal enlargements that are immunoreactive for DBH and fluoresce intensely in ultraviolet light after fixation in a solution of formaldehyde and glutaraldehyde or treatment with glyoxylic acid. No fluorescent neural structures were found in denervated rat kidney sections treated with glyoxylic acid. Many such structures are associated with arteriolar branches of interlobar, arcuate, and interlobular arteries and are composed, in part, of axonal enlargements that contain mitochondria, microtubules, and one or more clusters of synaptic vesicles. These perivascular nerve specializations may be sites of axoaxonal interactions between noradrenergic axons or between these axons and other types of autonomic or sensory axons. The synaptic vesicles evidently store large amounts of catecholamine, but there is no evidence whether it is released into the surrounding tissue. These structures may be involved in changes in intrarenal innervation patterns which may occur as the rat ages. Regardless of the autonomic or sensory nature of intrarenal neural structures, close association of most such structures with arterioles suggests some neurovascular interaction.

Animals↗
PubMed1989

The effect on father-infant interaction of demonstrating the neonatal behavioral assessment scale.

Forty-four first-time fathers who had attended prenatal classes and were present during labor and delivery of their healthy infants were divided randomly into an experimental group of 22 who observed the Brazelton neonatal behavioral assessment scale performed on their 2- to 3-day-old infants, or into a control group of 22 who did not receive this intervention. Paternal involvement in, and attitudes toward, infant caretaking and ratings of infant difficultness were compared in the two groups. Father-infant interaction was measured by two-minute videotape analysis at eight weeks postpartum. Paternal attitudes, caretaking activities, and perceptions of their infants were measured by questionnaire self-reports. There were significant differences in the quality, but not quantity, of father-infant interactions, and in one of four measures of infant difficultness (unpredictability) between the two groups.

Adult↗