Showing papers by "University of Vermont published in 1983"

Morphometric and biochemical studies of peripheral nerves in amyotrophic lateral sclerosis

Abstract: Phrenic nerves of 11 patients with amyotrophic lateral sclerosis studied postmortem contained only 33% of the normal number of large myelinated fibers (9 controls; p less than 0.001). In the phrenic nerves of these patients, there were 18% fewer large myelinated fibers in the distal segment than in the proximal segment (p less than 0.025). The ratio of axonal circumference to myelin lamellae in large myelinated fibers in the distal segment was 34% greater than that in control fibers (p less than 0.002). The proportion of acute axonal degeneration was the same at all levels (48.0 +/- 13.7%). Sural nerves of 21 patients with amyotrophic lateral sclerosis had more acute axonal degeneration and 30% fewer myelinated fibers (p less than 0.05) than controls; evidence of degeneration also extended to unmyelinated fibers. The amount of axonal transport of acetylcholinesterase in 9 sural nerves determined in vitro was reduced by 24% (p less than 0.05) and the apparent transport rate was reduced by 44% (p less than 0.01) compared with 4 controls. These findings show that in amyotrophic lateral sclerosis a small degree of dying-back change and of distal axonal atrophy is superimposed on the degeneration of motor neuron cell bodies, and that the disease effects spread beyond the motor neurons.

Anatomic and Prognostic Significance of New T-wave Inversion in Unstable Angina

Abstract: The significance of the development of new T-wave inversion was studied in 118 consecutive patients with unstable angina. The electrocardiograms during hospitalization in the coronary care unit were analyzed for occurrence of new T-wave inversion greater than or equal to 2 mm and correlated with findings at coronary angiography (73 patients) and at follow-up (112 patients). Twenty-nine patients had anterior T-wave inversion. Of these, 25 patients (86%) had greater than or equal to 70% diameter reduction of the left anterior descending (LAD) artery, compared with 11 (26%) of 42 patients without anterior T-wave inversion (p less than 0.001). The sensitivity of T-wave inversion for significant LAD stenosis was 69%, specificity 89%, and positive predictive value 86%. Two patients had T-wave inversion in the inferior leads. Both patients had significant right coronary artery disease, compared with 18 of 55 patients without inferior T-wave inversion (difference not significant [p = NS]. Seventy-one patients who were treated medically had 16 +/- 9 months' follow-up. Of 26 patients who had T-wave inversion, 10 (38%) had cardiac events, compared with 7 (16%) of the remaining 45 patients without T-wave inversion (p less than 0.05). Forty-one patients who had undergone coronary bypass surgery had 19 +/- 9 months' follow-up. Of 22 patients with T-wave inversion, 4 (18%) had cardiac events, compared with 2 (11%) of the remaining 19 patients without T-wave inversion (p = NS). Thus, development of new T-wave inversion greater than or equal to 2 mm in patients with unstable angina (1) is predictive of significant coronary artery stenosis, and (2) identifies a subgroup with poor prognosis when treated medically.

Siblings of handicapped children: a review.

Abstract: Research is critically reviewed and evaluated, first, in order to determine if the presence of a handicapped child in a family uniquely affects the nonhandicapped siblings, and, second, to identify factors mediating the nature and power of those effects. In addition, projects involving sibling therapy, education, and training are described. Currently there are few well-controlled empirical investigations supporting the popular belief that, as a group, siblings are adversely affected by their handicapped brothers or sisters. Rather, only certain siblings appear to be vulnerable to negative reactions, depending on such factors as sibling sex and birth order, family socioeconomic status, and parental responses to the handicapped child. Recommendations are offered for improved research strategies and questions and for the careful evaluation of future educational and support services for siblings.

Intracephalic embryonic neural implants in the adult rat brain. I. Growth and mature organization of birainstem, cerebellar, and hippocampal implants

Abstract: Implants of embryonic CNS tissue, dissected from the developing brainstem, cerebellum, and hippocampus of rat fetuses, were analyzed after 2–14 months survival in an intracephalic transplantation cavity in adult host rats. The mature anatomical organization of the implants was studied in specimens taken from early (embryonic day, (E) 12–14) and late (E17–20) gestational stages and compared with the results previously obtained in explant cultures and in experiments with transplants to the anterior eye chamber and to the brains of neonatal rats. The resulting volume of the implanted tissue is dependent on the gestational age of the donor fetus. For all regions analyzed the early gestational tissue develops to become larger than the late gestational tissue. Moreover, tissue dissected from different regions of the neuraxis at a specific developmental time point exhibits differing amounts of proliferation within the intracephalic cavity of the host. Though all early gestation transplants demonstrate continued cell genesis as indicated by their subsequent increase in size, late gestation brainstem specimens fail to show an increase in tissue volume and the late gestation cerebellar implants actually exhibit a reduction in final size. Early gestation hippocampal transplants demonstrate the greatest increase in tissue volume (over 3,800%) and completely fill the intracephalic cavity with no apparent encroachment upon the host CNS tissue. However, hydrocephalus was present in one host animal which contained a transplant contaminated by connective tissue that obstructed the lateral ventricle. Each implanted CNS region demonstrates cytoarchitectural features characteristic for the specific region in vivo. The results demonstrate that (1) neuroepithelial cells in the implants taken from various regions of the neuraxis can continue cell genesis after transplantation to an adult CNS environment; cells are capable of normal migration within the implant; and they continue to differentiate to produce neurons with many of their normal in vivo morphologic characteristics; (2) neurons generated before the embryonic tissue is taken for transplantation can, at least to some degree, survive and retain their cytoarchitectural features in the new environment; (3) many characteristics of the intrinsic organization and three-dimensional architecture of each CNS region can develop even in an ectopic intracephalic site in the adult host. These observations indicate that the in cerebro implantation technique can provide an extremely valuable experimental preparation in which to analyze various aspects of development which may influence the organization of specific CNS regions, including parameters that regulate the morphology of individual neurons. The developmental questions that can be explored with this technique should complement those which can be addressed with in vitro explant or reaggregation procedures and with the intraocular grafting technique. In particular, the intracephalic implantation technique should prove valuable for obtaining new insights into cellular events that determine the complex three-dimensional organization of the mammalian CNS during development.

Sexuality, distribution, and dispersal of Heterobasidion annosum in pine plantations of Vermont

Abstract: Mating experiments with monosporous isolates of H. annosum from red pine plantations in Vermont demonstrate that the fungus is heterothallic and unifactorial. Clamp connections are present in tissue isolates from basidiocarps and in mycelia formed from compatible matings. The distribution of clamp connections within these mycelia is irregular and the features of this character are described in detail. The incompatibility factor is multiallelic and 40 alleles were identified in our collections from 53 basidiocarps. These alleles were used as naturally-occurring genetic markers to examine the distribution of the fungus within plantations. The distributional data are used to contribute information regarding dispersal. The genetic evidence suggests that centers of infection within a plantation are not due to the extensive vegetative spread of single clones, but that multiple inoculations are common in the development of infection centers. Nevertheless, the vegetative growth of mycelium does occur across the root systems of adjacent trees.

Lizard malaria: cost to vertebrate host's reproductive success

Abstract: Plasmodium mexicanum is a common malarial parasite of the western fence lizard, Sceloporus occidentalis, in northern California, USA. Infected female lizards store substantially less fat during the summer activity season and produce smaller clutches of eggs than do non-infected animals. Stored fat is utilized in the production of eggs; the energy content of the decrement in stored fat is approximately equal to the energy content of the average reduction in number of eggs. Thus, there is ongoing strong selective pressure on the host to evolve appropriate anti-parasite measures.

The Kinetics of Early Inflammatory Events During Experimental Pneumonia Due to Legionella pneumophila in Guinea Pigs

Abstract: An animal model of Legionella pneumophila pneumonia was developed to study aerosol infection, pathogenesis, and pulmonary host defense mechanisms. Guinea pigs were exposed in an inhalation facility that limited the aerosol of L pneumophila to the snout. Bronchoalveolar lavage was used to sample airspace cells, secretions, and bacteria during developing infection in 79 exposed animals and 13 uninfected controls. An influx of polymorphonuclear neutrophils followed exponential bacterial growth during the initial three days of infection and coincided with limitation of the increase in bacteria recovered. A macrophage influx occurred at three to five days. Bacteria were eliminated from the lung by 11 days after exposure. Albumin in lavage fluid peaked at two days. Most viable L pneumophila organisms were associated with alveolar macrophages, whereas most of the bacteria associated with polymorphonuclear neutrophils were nonviable. Recruited, and possibly immune, defenses appear to be required for successful resolution of legionella pneumonia.

Intrathecal vincristine. Report of a fatal case despite CNS washout.

Abstract: The clinical course of a two-year-old girl with acute lymphocytic leukemia (ALL) who inadvertently received intrathecal vincristine is presented. Despite aggressive treatment with parenteral folinic acid and extensive central nervous system washout, the outcome was fatal. The pharmacologic aspects of vincristine and folinic acid that may explain why treatment was unsuccessful, are reviewed.

Temperature elevation in a beam of ultrasound.

Abstract: Computations are made of the temperature elevation expected at points along the axis of an unfocussed beam of ultrasound in a homogeneous absorbing medium. A simplified model is used in which the intensity is assumed uniform over a cross section. Heat conduction is taken into account, but not convection or perfusion. Results are presented for frequencies from 1 to 10 MHz and beam diameters from 0.2 to 2.4 cm. The results include limiting temperatures, reached at infinite time, as well as temperature vs time characteristics. As an example for certain conditions (transducer diameter 1.2 cm, frequency 4 MHz, intensity at the transducer 0.1 W/cm2, tissue acoustically similar to liver, transducer thermal conductivity similar to that of tissue) the temperature elevation produced at a distance 2 cm from the transducer is calculated to be 0.61°C after 253 s; it then increases more and more slowly, approaching, but never exceeding, 1.46°C.

Cellular immune mechanisms in Coxsackievirus group B, type 3 induced myocarditis in Balb/C mice

Abstract: Coxsackie B viruses are a common cause of viral myocarditis in humans. A murine model of the human disease has been developed using Coxsackievirus group B, type 3 and inbred Balb/c mice. Infection of T lymphocyte deficient mice does not result in significant myocarditis indicating the importance of T cells in this disease. The virus can be isolated from the hearts of T cell deficient and normal mice in equal concentrations. Virus elimination presumably is mediated by virus specific neutralizing antibody induced in both groups. T lymphocytes, natural killer cells and macrophage obtained from normal virus infected mice are all capable of lysing myofibers in vitro. Maximum lysis is obtained with the cytolytic T cells. When these cell populations or Coxsackievirus immune antibody were adoptively transferred into T lymphocyte deficient animals infected with the virus, only animals given T cells developed significant myocarditis.

Effect of cytochalasin D on smooth muscle contraction

Abstract: Cylindrical segments of extraparenchymal pulmonary artery (essentially a preparation of smooth muscle with regard to contractile capability) were isolated from adult male rats. They were mounted in an isometric muscle bath in physiological salt solution (PSS) in an environment of 95% O2/5% CO2. After allowing 1 h for equilibration, the maximum force generated by the tissue in response to a depolarizing solution was determined. After relaxation, vessels were incubated for 1 h in one of several concentrations of cytochalasin D (CD) (0.01, 0.05, 0.5, 1, 10 micrograms/ml) and the response to stimulation retested immediately after returning to PSS, and then at 30 minute intervals up to 2 h. CD inhibited the ability of vascular smooth muscle to generate force (contract) in a concentration-dependent manner. The inhibitory effect was reversible within a short period of time. Quantitative electron microscopic examination of these vessels suggested that CD disrupts the integrity of myofilaments, especially at sites of "dense bodies." Our results indicate that a percentage of actin in smooth muscle cells is not permanently in the filamentous "F" form, but is part of the G:F actin system of the cell, labile to polymerization:depolymerization. The ability of smooth muscle cells to generate force could depend on the proper functioning of the F:G actin "treadmill."

Cavernous sinus thrombophlebitis secondary to sphenoid sinusitis.

Abstract: Cavernous sinus thrombosis is a serious life threatening condition which usually results from midfacial skin infections. Preantibiotic era mortality rates of 80% have improved markedly because of an early awareness of the condition and prompt initiation of parenteral antibiotics. Sphenoid sinusitis is an uncommon associated cause of cavernous sinus infection and is itself a rare and elusive clinical problem. A case of sphenoid sinusitis and concurrent cavernous sinus thrombophlebitis is presented to highlight the clinical diagnostic considerations with special emphasis on bilateral eye signs as indicators of the impending thrombophlebitic process.

Further investigations of ATP release from human erythrocytes exposed to ultrasonically activated gas-filled pores.

Abstract: Suspensions of human erythrocytes in a firefly-extract solution were exposed to 2.0 MHz ultrasound in the presence of 3.4 μm dia. gas-filled pores. Lysis of the cells during ultrasonic exposure resulted in the release of ATP which produced light upon interaction with the firefly extract. The response was approximately proportional to the square of the SPTA intensity I for both continuous and pulsed exposures (1 μs pulses, 1:9 duty cycle) within the range 5–100 mW/cm 2 . One method of graphical data presentation yielded an apparent threshold for the effect at 0.31 bar pressure amplitude; however, a response could probably be obtained at any nonzero exposure level with a sufficiently sensitive apparatus. The response was also proportional to the exposure duration t for the range 0.03–3 s. The product I 2 t may have some significance as a dosage parameter for this system in an, as yet, undefined "low-dose" range. Measurements for exposures with higher intensities, longer durations, lower duty factors and with pulses longer than 300 μs deviated from these trends.