Mammalian somatic cell hybrids and their susceptibility to viral infection.
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Adenoviridae↗
Biomedical subjects
R Wang
Publications and source records attributed to R Wang.
Pad-plate diffusion assay for virginiamycin in mash-type feeds.
An assay procedure has been developed for virginiamycin in mash-type feeds which includes removing fat interferences from the feeds by a rapid petroleum ether wash, a citric acid extraction, an acetone extraction, and the use of the pad-plate diffusion system. The procedure eliminates the need for compensatory curves prepared from feeds of the same or similar composition. Recoveries from 10 laboratory-prepared feeds containing 11.0 micrograms virginiamycin/g averaged 89.3% with a coefficient of variation (CV) of 5.76%. Recoveries from a laboratory-prepared feed containing 13.2 micrograms virginiamycin/g averaged 89.9% (CV 9.92%). The procedure is simple, reasonably accurate, and precise.
Animal Feed↗
Tunica vaginalis sperm reservoir in a monkey model of vas deferens obstruction.
Repeat microscopic epididymal sperm aspiration (MESA) is used to treat congenital absence of the vas deferens (CAVD). Use of alloplastic implants as reservoirs results in poor sperm motility and pregnancy rates. An autoplastic tunica vaginalis reservoir for epididymal sperm has been used in four patients, with one resultant pregnancy. We studied this technique in a monkey model. Eight reservoirs were created in four monkeys (Cercopithecus aethiops). The vas deferens was ligated close to the epididymis. A transverse incision was made in the caput epididymis, and sperm were aspirated for analysis. Cut margins of the epididymal duct were sutured open to the visceral layer of the tunica vaginalis. The defect in the parietal layer of the tunica vaginalis was repaired, and sterile Tyrode's solution was instilled in the potential space between the parietal and visceral layers. Initial epididymal sperm obtained at the creation of the sperm reservoir demonstrated adequate mean motility (60.5%, grade 1.5), morphology (82.8% normal), and viability by Eosin-Y exclusion (69.9%). At 4 weeks, no reservoirs were palpable. Percutaneous aspiration (25-gauge angiocatheter) yielded no fluid. Surgical exposure of the reservoirs demonstrated significant adhesions and scar formation between the parietal and visceral layers of the tunica vaginalis, obliterating the potential space. No sperm were detected in irrigant fluids at this time. In conclusion, adhesion and scar formation may prevent use of the tunica vaginalis reservoir as an alternative to repeat MESA in treatment of CAVD.
Animals↗
The detrimental effects of electric current on normal human sperm.
This in vitro study was conducted to determine the direct effects of electric current and associated increase in temperature on human sperm. Washed sperm samples from normal volunteers were subjected to an electric current (0 to 100 mA) in a small, customized Plexiglas chamber for up to 10 minutes. Resistive heating was monitored by a miniature temperature probe. An aliquot (7 microliters) obtained from the exposed sample (at 0, 3, 7, and 10 minute intervals) was evaluated for sperm motion parameters, viability, gross morphology, and electron microscopic analyses. As the current increased, there was a time-dependent decrease in the percentages of motility, viability, and curvilinear velocity. Light and electron microscopic evaluations of the sperm showed no demonstrable damage to the head, mid piece, or tail regions on electric stimulation. A gradual time-dependent increase in the temperature of the medium was observed with electric current. Separate evaluations in the absence of an electric current showed a significant increase in percent motility and curvilinear velocity until 40 degrees C. These results suggest that an electric current, independent of temperature (up to 40 degrees C), is detrimental to sperm motion and viability. Further studies are indicated to evaluate whether electric current during electroejaculation may be in part responsible for poor sperm recovery in men with spinal cord injury.
Electricity↗
Adhesion of silicone to polyurethane in maxillofacial prostheses.
Primers have been reported to increase adhesion between silicone elastomers and polyurethane liners used for maxillofacial prostheses. This study evaluated two primers, three polymerization methods, and seven primer reaction times to determine the conditions for optimum adhesive bond strength. The T-peel strength of specimens was determined as described in ASTM Standard D 1876-72. Failure modes were evaluated, and two-sample t tests and one-way ANOVA were used to compare means for significant (P < .05) differences. Bond strengths were significantly greater for polyurethane treated with primer 1205 rather than S-2260 regardless of the polymerization method or primer reaction time. Neither any single polymerization method nor single primer reaction time consistently yielded greater bond strengths.
Adhesiveness↗
Effect of cryoprotective additives and cryopreservation protocol on sperm membrane lipid peroxidation and recovery of motile human sperm.
Sperm membrane damage during cryopreservation reduces the recovery of motile sperm. The present study investigates changes in sperm motility and membrane lipid peroxidation (LPO) in response to two changes in the standard sperm cryopreservation/thawing methodology: 1) the addition of platelet-activating factor (PAF) and pentoxifylline (PTX) as cryoprotective additives, and 2) the alteration of sample thawing time. PAF (1 microM) and PTX (3 mM) were added to fresh sperm samples prior to cryopreservation. After 2 weeks the samples were thawed either quickly (5 minutes at 37 degrees C) or slowly (30 minutes at 4 degrees C) and evaluated for sperm motility and LPO. Thawing time influenced both post-thaw motility and LPO. Samples thawed quickly exhibited a 31% increase in motility recovery (35.2 +/- 4.3% in quick-thaw samples; 24.3 +/- 3.9% in slow-thaw samples) and a 23% lower LPO level (23.3 +/- 3.4% in quick-thaw samples; 30.09 +/- 4.4% in slow-thaw samples) compared to samples thawed slowly. Results also demonstrated that PAF (49 +/- 1.7%) or PTX (42.6 +/- 1.5%) enhance post-thaw motility in comparison to control (35.8 +/- 1.2%), whereas neither PAF nor PTX affect post-thaw LPO (19.1 +/- 2.2% in controls; 20.2 +/- 1.7% in PAF samples; 20.5 +/- 1.4% in PTX samples). These results support observations that there is a negative correlation between sperm motility and LPO in cryopreserved samples. The results also discount the hypothesis that LPO protection is a result of the cryoprotective action of PAF or PTX.
Cell Membrane↗
Comparison of responses to adrenomedullin and calcitonin gene-related peptide in the feline erection model.
The purpose of the present study was to investigate the effects of intracavernosal injections of adrenomedullin (ADM) and calcitonin gene-related peptide (CGRP), two structurally similar peptides, on penile erection in the anesthetized cat. Erectile responses to ADM and CGRP were compared with responses to a standard drug combination (1.65 mg papaverine, 25 microg phentolamine, and 0.5 microg prostaglandin E1 [PGE1]). Intracavernosal injections of ADM (0.1-3 nmol) and CGRP (0.01-0.3 nmol) induced erection in a dose-dependent manner. The maximal increase in intracavernosal pressure in response to ADM was a 75% increase, while the maximal response to CGRP was comparable to that induced by the reference combination, and the maximal increase in penile length was comparable with ADM, CGRP, and the standard drug combination. The duration of the maximal pressure increase and the total duration of the response to ADM and CGRP were more abbreviated than with the control combination, and systemic blood pressure was reduced significantly after administration of CGRP, the control combination, and the higher doses of ADM. The nitric oxide synthase inhibitor, L-NAME, and the K+(ATP)-channel antagonist, glybenclamide, had no effect on the erectile response to CGRP or ADM. The CGRP receptor antagonist CGRP(8-37) attenuated the erectile response to CGRP but not to ADM. These data suggest that the erectile responses to ADM and CGRP are not mediated by nitric oxide release or the opening of K+(ATP) channels, two mechanisms reported to be involved in penile erection, and that CGRP and ADM induce penile erection by activating different receptors.
Adrenomedullin↗
Dosimetric measurement of scattered radiation from dental implants in simulated head and neck radiotherapy.
The purpose of this study was to examine the dose enhancement at bone-implant interfaces from scattered radiation during simulated head and neck radiotherapy. Three cylindric implant systems with different compositions (pure titanium, titanium-aluminum-vanadium alloy, titanium coated with hydroxyapatite) and a high gold content transmandibular implant system (gold-copper-silver alloy) were studied. Extruded lithium fluoride single crystal chips were used as thermoluminescent material to measure radiation dose enhancement at 0, 1, and 2 mm from the bone-implant interface. The relative doses in buccal, lingual, mesial, and distal directions were also recorded and compared. The results indicated that the highest dose enhancement occurred at a distance of 0 mm from the bone-implant interface for all the implant systems studied. The transmandibular implants had higher scattered radiation than other groups at 0 mm and at 1 mm from the bone-implant interface. There was no significant difference of dose enhancement between buccal, lingual, mesial, and distal directions. Titanium implants coated with hydroxyapatite demonstrated the best results under the simulated irradiation.
Alloys↗
The influence of castration on pharmacologically induced penile erection in the cat.
The purpose of this study was to investigate the in vivo effects of intracavernosal injections of adrenomedullin (ADM), calcitonin gene-related peptide (CGRP), nociceptin, vasoactive intestinal polypeptide (VIP), sodium nitroprusside (SNP), and prostaglandin E1 (PGE1) on penile erection in castrated and intact (control) anesthetized cats. Erectile responses to ADM, CGRP, nociceptin, VIP, SNP, and PGE1 were compared with responses to a standard triple-drug combination (1.65 mg of papaverine, 25 microg of phentolamine, and 0.5 microg of PGE1) in both castrated and control cats. In control animals, ADM, CGRP, nociceptin, VIP, SNP, and PGE1 induced penile erections similar to those elicited by the triple-drug combination. However, in castrated animals, there was a significant decrease in erectile response; the response to intracavernosal injection of the standard triple-drug combination in castrated cats was 28% of that of the control group of animals. Serum testosterone levels demonstrated a significant (P < 0.0001) positive correlation (r = 0.52) with intracavernosal pressure in response to the standard combination. A marked reduction in serum testosterone levels was observed in castrated cats when measured by radioimmunoassay (0.34 +/- 0.1 ng/dl in castrated cats, compared with 31.15 +/- 6 ng/dl in control cats). These data suggest that the presence of testosterone is a necessary prerequisite to sustain a pharmacologically induced penile erection in the cat.
Alprostadil↗
[Tyr1]-nociceptin and nociceptin have similar naloxone-insensitive erectile activity in the cat.
The heptadecapeptide nociceptin, also known as Orphanin FQ, is a newly discovered endogenous ligand for the opioid-like G-protein-coupled receptor ORL1. The present study was undertaken to investigate responses to intracavernosal injections of the nociceptin analog [Tyr1]-nociceptin and to investigate the effects of naloxone on erectile responses in anesthetized cats to [Tyr1]-nociceptin and to nociceptin. Intracavernosal injections of [Tyr1]-nociceptin and of nociceptin in doses of 0.3-30 nmol elicited dose-related increases in cavernosal pressure, which, at the highest dose studied, were comparable to increases induced by the triple-drug standard (papaverine, phentolamine, and prostaglandin E1), a preparation used in the treatment of erectile dysfunction. Responses to [Tyr1]-nociceptin were rapid in onset and had a time course similar to responses to nociceptin. Metenkephalin increased cavernosal pressure, whereas injections of nociceptin-(2-17), dynorphin A, and beta-endorphin did not alter cavernosal pressure. Erectile responses to nociceptin and to [Tyr1]-nociceptin were not altered after administration of the opioid receptor antagonist naloxone at a time when erectile responses to metenkephalin were attenuated. These data show that [Tyr1]-nociceptin and nociceptin have similar naloxone-insensitive erectile activity in the cat.
Amino Acid Sequence↗