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Biomedical subjects

S Ward

Publications and source records attributed to S Ward.

At least 307 records · Page 17Linked to original sources
PubMed1979

Pericardial-fluid complement: normal values.

Reports of low pericardial-fluid complement levels in systemic lupus erythematosus and rheumatoid arthritis have been difficult to interpret, as few data are available to describe complement concentrations in patients without pericardial disease. The authors therefore determined normal values under standardized conditions of collection, storage, and assay. The normal ranges for pericardial-fluid C3, C4, and total hemolytic complement were 35-127 mg/dl, 6.3-23 mg/dl, and 1.9-9.1 CH50 units, respectively. Storage at -20 C resulted in a 50% reduction in values. Hence, storage at -70 C is recommended. As the level of pericardial-fluid total hemolytic complement is normally low, caution is needed in interpreting its apparent reduction in various immunologic diseases.

Complement C3↗
PubMed1979

Factors determining the mortality and morbidity in hepatic injuries. Analysis of 108 cases.

The experience with 108 cases of hepatic injuries was reviewed retrospectively and a classification based on the severity of the hepatic injury was used to group these patients accordingly. Using this criteria, the factors determining the observed morbidity and mortality were analyzed. Hepatic injuries amenable to relatively simple surgical treatment were found in 72 patients (67%). Nine deaths occurring in this group were attributed to the commonly encountered associated injuries inside and outside the abdomen. Moderately severe imjuries requiring suturing of the hepatic parenchyma and ligation of injured vessels and bile ducts were seen in 15 patients (14%). Two of these patients died. Severe hepatic injuries resulting in major blood loss requiring partial hepatectomy were seen in 21 patients (19%). Seven of the eight deaths (7.4%) attributable to the hepatic injury occurred in this group. As noted, ten other patients died from causes other than the hepatic injury for an overall mortality of 16.7%. A pre-established patient management program based on the classification of hepatic injuries is proposed as a method for improving the management of patients with hepatic injuries.

Abdominal Injuries↗
PubMed1979

Behavioral responses of Schistosoma mansoni miracidia in concentration gradients of snail-conditioned water.

Movement patterns of Schistosoma mansoni miracidia were examined in several concentrations and gradients of snail-conditioned water (SCW). Miracidia surrounded by uniform concentrations of SCW swam at the same speed and exhibited the same rate of turning (angular velocity) as did control miracidia swimming in spring water. However, miracidia in gradients of SCW exhibited a 3-fold increase in their angular velocity without altering their swimming speed. Miracidia ascending gradients of SCW did not increase their angular velocity and failed to orient to the gradient of the stimulant. In contrast, miracidia which encountered sufficiently abrupt decreases in SCW concentration, while descending the gradient, sharply increased their angular velocity. This behavior caused miracidia to remain in regions of high concentration of stimulant. The magnitude of decrease in SCW concentration needed to evoke this response depended on the absolute concentration of SCW. Thus, the miracidial response is a "boundary reaction", a form of chemoklinokinesis, and not a chemotaxis.

Animals↗
PubMed1978

Fitts' law as a function of system dynamics and target uncertainty.

Fins' law was found to hold for discrete movements executed by subjects controlling the velocity of a cursor with a control stick The slope of movement time versus index of difficulty was approximately twice as large as for a comparable position control system. Target uncertainty also increased the slope of total time versus index of difficulty, and this effect is interpreted in terms of adaptive tuning of the human movement system.

Journal Article↗
PubMed1978

Characterization of temperature-sensitive, fertilization-defective mutants of the nematode caenorhabditis elegans.

The isolation and characterization of three Caenorhabditis elegans temperature-sensitive mutants that are defective at fertilization are described. All three are alleles of the gene fer-1. At the restrictive temperature of 25 degrees, mutant hermaphrodites make sperm and oocytes in normal numbers. No oocytes are fertilized, although they pass through the spermatheca and uterus normally. The oocytes can be fertilized by sperm transferred by wild-type males, indicating that the mutant defect is in the sperm. The temperature-sensitive period for the mutants coincides with spermatogenesis. Sperm made by mutants at 25 degrees cannot be distinguished from wild-type sperm by light microscopy. The sperm do contact oocytes in mutant hermaphrodites, but do not fertilize. Mutant sperm appear to be nonmotile. Mutant males are also steril when grown at 25 degrees. They trnasfer normal numbers of sperm to hermaphrodites at mating, but these sperm fail to migrate to the spermatheca and are infertile. The phenotype of these mutants is consistent with a primary defect in sperm motility, but the cause of this defect is not known.

Animals↗
PubMed1978

A simple quantitative technique for testing behavioral responses of Schistosoma mansoni miracidia to chemicals.

We describe a new technique for testing responses of Schistosoma mansoni miracidia to chemicals. Miracidia in spring water were placed in a chamber shaped like the Greek letter phi. Small volumes of test chemicals were inoculated into one side of the chamber. After 30 sec a dam was inserted to bisect the chamber and the percentage of miracidia on the inoculated side was calculated. Reproducible quantitative results were obtained using the known miracidial stimulants, snail-conditioned water (Biomphalaria glabrata) and Mg2+; up to 80% of the miracidia were recovered on the inoculated side of the chamber. Other substances also stimulated miracidia: several inorganic cations, 4 neurotransmitters, 3 acetycholine antagonists, and 1 acetycholine agonist. Modifying the technique by testing stimulants in altered chemical "backgrounds" allowed us to test for inhibitors of miracidial responses. Assays of the Mg2+ content of several of the test solutions indicated that their stimulatory or inhibitory effects could not be ascribed to Mg2+ contamination. However, results obtained with neurotransmitters and drugs were not sufficiently consistent to implicate specific neurotransmitters in the mechanism by which miracidia detect and respond to stimulants in snail-conditioned water.

Acetylcholine↗
PubMed1976

Ultrastructural studies in epidermolysis bullosa hereditaria. III. Recessive dystrophic types with dermolytic blistering (Hallopeau-Siemens types and inverse type).

Ultrastructural examination was performed in 42 biopsy specimens from 22 patients with the Hallopeau-Siemens types or with the inverse type of epidermolysis bullosa dystrophica recessiva. The patient group consists of 8 cases of the localized Hallopeua-Siemens type, 9 of the generalized Hallopeau-Siemens type and 5 of the inverse type. The origins of the biopsy specimens are involved, intact and experimentally frictioned skin from blister-predilected sites, as well as clinically normal skin from nonpredilection sites. It is confirmed that all the blisters initiate below the basal lamina. Anchoring fibrils are moderately to markedly decreased in most cases, while they are normal in 3 other cases. It is thought that secondary degradation of anchoring fibrils and/or collagen fibrils plays an important role in blistering mechanism in the Hallopeau-Siemens and inverse types of recessive dystrophic epidermolysis bullosa, whereas a primary aplasia of anchoring fibrils as causative defect has been out ruled.

Collagen↗
PubMed1975

Electron microscopical reconstruction of the anterior sensory anatomy of the nematode Caenorhabditis elegans.

The complete structure of the anterior sensory nervous system of the small nematode C. elegans has been determined by reconstruction from serial section electronmicrographs. There are 58 neurons in the tip of the head. Fifty-two of these are arranged in sensilla. These include six inner labial sensilla, six outer labial sensilla, four cephalic sensilla and two amphids. Each sensillum consists of ciliated sensory neurons ending in a channel enclosed by two non-neuronal cells, the sheath and socket cells. The amphidial channel opens to the outside as does that of the inner labial sensilla so that these probably contain chemoreceptive neurons. The endings of the other sensilla are embedded in the cuticle and may be mechanoreceptive. The cell bodies of all the neurons lie near the nerve ring and their axons project into the ring or into ventral ganglia. One of the ciliated sensory neurons in each of the six inner labial sensilla makes direct chemical synapses onto a muscle making these sensory-motor neurons. The anatomy of four isogenic animals was compared in detail and found to be largely invariant. The anatomy of juveniles is nearly identical to that of the adult, but males have four additional neuron processes.

Animals↗
PubMed1973

Chemotaxis by the nematode Caenorhabditis elegans: identification of attractants and analysis of the response by use of mutants.

The nematode Caenorhabditis elegans is attracted by at least four classes of attractants: by cyclic nucleotides, cAMP and cGMP; by anions, Cl(-), Br(-), I(-); by cations, Na(+), Li(+), K(+), Mg(+); and by alkaline pH values. The nematode's behavioral response to gradients of these attractants involves orientation and movement up the gradient, accumulation, and then habitutation. Comparison of the tracks of wild-type and mutant animals responding to gradients of attractants indicates that sensory receptors in the head alone mediate the orientation response and that the direction of orientation is determined by the lateral motion of the head. Therefore, the orientation response is a klinotaxis.

Acetates↗