Creation and use of a composite polyurethane-expanded polytetrafluoroethylene graft for hemodialysis access

The Thoratec (Vectra) polyurethane vascular access graft (TPVA) is among the most recent additions to the list of materials used to construct prosthetic grafts for vascular access during hemodialysis. We give the TPVA very high marks, and recognize the utility of such a graft for use in hemodialysis. However, the strong elasticity of this graft can lead to unexpected complications after suturing. We devised a new surgical method using a TPVA-ePTFE (expanded polytetrafluoroethylene) composite graft, substituting the anastomosis section of the TPVA with a portion of ePTFE graft material, and have been able to overcome most of the TPVA's potential problems. We herein describe the technique.     

Kinetics and staining properties of mast cells proliferating in rat small intestine tunica muscularis and subserosa following infection with Nippostrongylus brasiliensis

Mucosal mast-cell hyperplasia occurs in the rat small intestine mucosa after infection with Nippostrongylus brasiliensis. In the present study, the number of mast cells was found to increase in the muscularis and subserosa as well as in the mucosa of rat small intestines 2-3 weeks after infection with this nematode. Mast cells in the muscularis were stained blue by the alcian blue/safranin sequence and did not bind berberine sulfate. The staining was blocked when tissues were fixed in neutral formalin. The increase in mast cells was transient and gradually disappeared; the half-life was 40 days. After an intravenous administration of compound 48/80, mast cells in the muscularis did not discharge granules. The results indicate that these mast cells were of the mucosal type. The mast cell phenotype in the muscularis did not change even 12 weeks after infection. Mast cells in the subserosal tissue were first of the mucosal type as were those in muscularis. After 8-12 weeks, however, many subserosal mast cells became positive for berberine sulfate and safranin. These results show that mucosal-type mast cells do not undergo phenotypic changes during the period of observation when these cells appear in the muscularis but the phenotypic expression may change as the cells arise in subserosal tissue.     

Functional organization of premotor neurons in the cat medial vestibular nucleus related to slow and fast phases of nystagmus

Summary Extracellular spikes were recorded from secondary vestibular neurons in the cat medial vestibular nucleus (MVN) and were identified as type I or II neurons by horizontal rotation. Type I neurons were further classified as excitatory or inhibitory premotor neurons on the basis of their axonal termination in the contralateral or ipsilateral abducens nucleus, demonstrated by spike-triggered averaging of abducens nerve discharges, or by antidromic activation using systematic microstimulation within the abducens nucleus.Both excitatory and inhibitory premotor type I MVN neurons exhibited a rhythmic modulation of their firing rate in association with nystagmus elicited by rotation or electrical stimulation of the vestibular nerve. Their tonic activity during the slow phase was suppressed at the quick phase directed to the ipsilateral side.Excitatory type I MVN neurons terminating in the contralateral abducens nucleus sent collateral axons to the contralateral MVN. These commissural neurons also showed a nystagmus-related discharge pattern.Type II MVN neurons activated at short latency by stimulation of the contralateral vestibular nerve exhibited burst discharges when the activity of ipsilateral type I neurons was suppressed at the quick phase. These type II neurons made monosynaptic inhibitory connections with type I neurons as shown by the post-spike average of the membrane potential of secondary MVN neurons triggered from spikes of single type II neurons. Thus, the inhibitory action originating from burst activity of type II MVN neurons contributes to suppression of type I premotor MVN neurons during fast eye movements.Supported by Grant-in-Aid for Scientific Research No. 248106 from Japan Ministry of Education, Science and Culture. Dr. Schor was supported by the Research Fellowship of Japan Society for the Promotion of Science (JSPS)     

Fine structure of the myotendinous junction and “terminal coupling” in the skeletal muscle of the lamprey,Lampetra japonica

The myotendinous junction in the skeletal muscle of adult lamprey Lampetra japonica was studied with an electron microscope. Numerous finger-like sarcolemmal invaginations were present at the ends of muscle fibers to form the myotendinous junction. Parietal fibers of each muscle unit showed more closely distributed sarcolemmal invaginations than central fibers. Features of the myotendinous junction. Parietal fibers of each muscle unit showed more closely distributed sarcolemmal invaginations than central fibers. Features of the myotendinous junction generally conform to the accounts in the literature. The sarcolemmal invagination was covered on its sarcoplasmic aspect by the connecting filament layer and the dense amorphous attachment layer, and on the extracellular aspect by the intermediary layer and the external lamina with collagen fibrils arising from the myosepta. Sarcolemmal invaginations were sometimes seen to consist of a pair of sarcolemmas of adjacent muscle fibers within a muscle unit, which is characteristic to the myotendinous junction of lamprey. It is noteworthy that the connecting filament layer is much thinner than that, e.g., in the tadpole tail muscles (Nakao, '74). Furthermore, it is much thicker in the parietal fibers than in the central fibers. The sarcolemma of the terminal segment of the invagination frequently showed specific coupling with cisterns of the sarcoplasmic reticulum (terminal coupling). The external lamina is partially or completely deficient in the terminal segment of sarcolemmal invaginations which form terminal couplings so that collagen fibrils contained in the invagination appear to be in direct contact with the sarcolemma; however, definite relationships of collagen fibrils with the sarcolemma and the external lamina in the terminal segment of invagination still remain obscure. This type of coupling is considered to play a role in the coupling of excitation to contraction of muscle fibers as triads and diads.     

Personality of seasonal affective disorder analyzed by Tri-dimensional Personality Questionnaire

BACKGROUND: Although there have been numerous reports in personality of mood disorders, there have been few reports in regard with personality of winter seasonal affective disorder (SAD). Furthermore, no reports have been published concerning summer SAD personality characteristics. Thus, this study was conducted to assess the personality of winter and summer SAD using Tri-dimensional Personality Questionnaire (TPQ) that have been used in a variety of mental disorders. METHODS: A total of 6135 Japanese were evaluated with TPQ, the Seasonal Pattern Assessment Questionnaire (SPAQ) and the Self-rating Depression Scale (SDS). Winter, summer and non-SAD groups were classified by SPAQ. We compared the difference of personality trait among these three groups in consideration of gender, age and SDS score influence. RESULTS: Winter SAD demonstrated higher "Novelty Seeking" and "Harm Avoidance"; summer SAD showed higher "Harm Avoidance" than the non-SAD group. "Harm Avoidance" in both SAD groups was re-analyzed using SDS score as a covariate, and "Novelty Seeking" in winter SAD using age as a covariate. As a result, the significance of high "Novelty Seeking" and high "Harm Avoidance" in winter SAD was excluded. However, "Harm Avoidance" remained the significant difference between summer and non-SAD. LIMITATION: SAD was diagnosed only by SPAQ and not by interview. The state-dependency of "Harm Avoidance" was not confirmed in identical patients over lapse of time. CONCLUSION: Patients with winter SAD have high "Harm Avoidance" dependent on the depressive state that is in accordance with non-seasonal depression. Patients with summer SAD have high "Harm Avoidance" possibly independent from the depressive state.     

Long-term observation of immunologic reconstitution after allogeneic bone marrow transplantation: differences in recovery among functional T cell subsets

A 27-year-old male with acute lymphoblastic leukemia in the first relapse received allogeneic marrow graft from an HLA-identical sister on April 28, 1978. We studied in vitro immunologic parameters such as T cell surface phenotypes, proliferative response to PHA and Con A; T cell suppressor and helper function for in vitro immunoglobulin production stimulated with pokeweed mitogen serially after the transplantation. Despite a low OKT4/OKT8 ratio for more than 5 yrs after marrow grafting, proliferative response to PHA recovered to normal 4 yrs and 9 months post-transplant. In contrast, proliferative response to Con A did not recover. T cell suppressor function induced by Con A had recovered at 3 yrs 6 months; however helper T cell function took longer to recover. These findings suggest differences in functional recovery of T cell subsets following allogeneic marrow transplantation.