Biomedical subjects
Publications and source records attributed to Y C Lin.
The acute scrotum in infants and children is generally due to torsion of the spermatic cord, torsion of the appendix testis, or acute epididymitis. An infant is presented who was found to have epididymitis and a scrotal abscess due to Haemophilus influenzae type b at the time of surgical exploration for suspected torsion of the spermatic cord.
Immunoglobulin heavy-chain switching is effected by a DNA recombination event that replaces the C mu gene with one of the other heavy-chain constant-region (CH) genes located 3' to the C mu gene. How the specificity of this event is controlled is unknown. However, it has been shown that IgM+ cells capable of switching to specific isotypes have the corresponding unrearranged CH genes in an accessible or active chromatin state, as demonstrated by the fact that these specific CH genes are hypomethylated and are transcriptionally active. We now report that the RNAs transcribed from specific unrearranged CH genes are induced prior to switching under conditions that promote switching to these specific CH genes. For example, we find that bacterial lipopolysaccharide, which induces the IgM+ cell line I.29 mu to switch to IgA, induces transcripts from the germ-line C alpha gene(s) in I.29 mu cells prior to switch recombination. Two preparations of T-cell lymphokines (recombinant interleukin 4 and supernatant from the T-cell line 2.19, which contains interleukins 4 and 5) that promote switching to specific isotypes by lipopolysaccharide-treated spleen cells induce transcripts from the corresponding germ-line CH genes prior to expression of the new isotypes. For example, interleukin 4, which appears to be necessary for switching to IgE in vitro and in vivo, induces within 2 days large increases in germ-line C epsilon transcripts in lipopolysaccharide-treated spleen cells and in I.29 mu cells. The most straightforward interpretation of our data is that these lymphokines direct switching to specific isotypes by activating specific CH genes, making them accessible to the putative switch recombinase.
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Recreational diving is a popular sport, although human ability to stay in and under water is severely limited physiologically. An understanding of these limitations enhances safety and enjoyment of sports diving. Breath-hold diving involves head-out water immersion, apnoea and submersion, exercise, cold stress, and pressure exposure. Each of these components, by itself, elicits prominent and specific physiological effects. Combination of these factors produces a unique and interesting physiological response generally known as diving reflex. Humans display weak diving responses, but exhibit no oxygen conservation function. Nevertheless, application of diving-induced physiological changes is now finding its way into clinical practice. Apnoea, face immersion, and head-out water immersion all show promise of clinical application. There are several spin-offs from diving research worth noting. Diuresis, enhancement of cardiac performance, and redistribution of blood flow, all produced by head-out water immersion, have been shown to be clinically useful, besides providing physiological data useful to space travel. Results from investigations on apnoea have been shown to be relevant to the following: treating some forms of cardiac arrhythmias; understanding drowning, sudden infant death syndrome and sleep apnoea; and confirming hyperventilation as the major cause of drowning. In comparison to marine mammals, humans are poor divers because of severe physiological constraints which limit their breath-hold time, diving depth, and ability to conserve body heat. Although under special circumstances humans can achieve unusually long breath-hold time and reach exceptional depth with a single breath, the sustainable working time and depth are only about 1 minute and 5 metres, respectively. Hypothermia inevitably results in divers working in the ocean. Without thermal protection, the intolerable limit of 35 degrees C is reached within 30 minutes in winter (10 degrees C) water and within 60 to 90 minutes in summer. Nevertheless, effective harvest work can be performed by humans in the ocean, and recreational benefits enhanced when these physiological limitations are respected. An unusual circulatory state exists during head-out water immersion in that there is a sustained increase of stroke volume. This results in 30% increase in cardiac output when the subject is resting in thermal neutral water, indicating a substantial overperfusion for the oxygen requirement. Furthermore, animal experiments showed that the elevated blood flow is preferentially channeled to the liver, fat, and the organs in the splanchnic region.(ABSTRACT TRUNCATED AT 400 WORDS)
A study was designed to examine the testicular function of male offspring rats produced by diabetic dams. A marked decrease in testosterone response to exogenous administration of gonadotropin-releasing hormone (GnRH) was found in male offspring of female rats made diabetic by administration of streptozotocin during early pregnancy. Control rats responded to GnRH with a marked increase in serum testosterone within 4-h postinjection. Male offspring of diabetic female rats demonstrated an unexpected decrease in serum testosterone in response to GnRH when compared with saline-injected rats. The results suggest that a defect in Leydig cell function may occur in the male offspring of diabetic female rats. However, a decreased release of pituitary LH in response to exogenous GnRH stimulation cannot be excluded as a cause of the lower testosterone values.
When Japanese quail were given gossypol acetic acid intramuscularly at 25 mg/kg body weight per day for 9 days, testis/body weights were reduced to 63% of those of controls. Lumina of the seminiferous tubules became smaller but were packed with tails of spermatids. Mitochondria of spermatids changed in shape from elongated to round. After administration of gossypol for 21 days, testis/body weights were 14% of those of controls. Lumina of seminiferous tubules were completely collapsed, germinal epithelia became much thinner, and basal lamina of the germinal epithelium underwent extensive ruffling. Although primary spermatocytes were seen, neither spermatids nor sperm were present. The cytoplasm of germinal epithelial cells was packed with numerous lipid droplets. At Day 8 of withdrawal following 21 days of gossypol administration, testis/body weights were 23% of those of controls. Reduced numbers of lipid inclusions and partial recovery of spermatogenesis in the testis were observed. In the epididymal region, epithelial cells of the ductuli efferentes progressively accumulated lipid droplets, and luminal collapse was seen after 21 days of gossypol administration. After gossypol administration for 21 days, no sperm were found in the ductus epididymidis, the lumina were collapsed, and microvilli of the epithelial cells were lost. At Day 8 of withdrawal after 21 days of gossypol administration, lipid content was reduced in the ductuli efferentes. The lumina of the ductus epididymidis were open, but no spermatozoa were seen. These observations indicate that gossypol severely altered tissues of the quail testis and epididymal region. However, this alteration seems to be reversible.
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Relative bradycardias have been reported to occur in humans both at rest and during exercise under a variety of hyperbaric conditions. Review of existing data reveals that there are two major mechanisms operating: one depends on hyperoxia and the other does not. While it is clear that hyperoxia produces bradycardia by a variety of well understood mechanisms, the non-oxygen-dependent causes of hyperbaric bradycardia have not been defined. Experimental results from animals studies have eliminated the involvement of increased ambient pressure and gas density in the development of hyperbaric bradycardia, in all normoxic conditions. This review considers two other possibilities, the altered respiratory pattern which may modify the HR secondarily, and circulatory deconditioning under hyperbaric environments, which masks the hyperbaric bradycardia. We propose that the return of a normal sea level HR following the initial bradycardia represents, in effect, bradycardia which would be seen if cardiovascular deconditioning were not present. It is concluded that hyperoxia is the major factor responsible for initiating and maintaining hyperbaric bradycardia, whereas non-oxygen dependent hyperbaric factors may alter respiratory patterns and secondarily cause a reduction in HR.
The studies in this report evaluate the inhibitory effects of long-term gossypol acetic acid (gossypol) administration on spermatozoal lactate dehydrogenase (LDH-X) activity, fertility and reversibility. Gossypol at 20 mg/kg/day or vehicle only was administered orally to adult male rats for 5 consecutive weeks. Groups of control and gossypol-treated rats were sacrificed at 2-, 4-, and 5-week intervals when LDH-X analysis of spermatozoa were prepared from the tail of the epididymis. An additional group of control and gossypol-treated rats were allowed to recover for up to 8 weeks after withdrawal of the treatment. In the gossypol-treated rats, the spermatozoal LDH-X activity was depressed by 80% of control level after a 5-week treatment period. There was no significant difference in spermatozoal LDH-X activity between the control and treated animals at 2 and 4 weeks. However, the number of ejaculated sperm estimated from the vaginal smear preparations after each mating was significantly less than the control values after 2, 4 and 5 weeks of treatment. At 5 weeks after the cessation of gossypol treatment, the spermatozoal LDH-X activity had only partially recovered but the fertility (number of ejaculated sperm, embryo implantation sites and pups born) had recovered to a level comparable to the control values 5 weeks after the cessation of gossypol treatment. The inconsistencies in the response of spermatozoal LDH-X activity, sperm number and fertility to gossypol may suggest that the antifertility action of gossypol and spermatozoal LDH-X activity in adult male rats may not be directly related as suggested by the results generated from the in vitro studies.
In this paper, 34 samples, 25 from 18 cervical carcinoma patients and 9 from 8 non-cervical carcinoma patients, were assayed using (alpha-32P) dCTP HSV-2 DNA probe and nucleic acid hybridization technic. It was shown that the positive rates of HSV-2 DNA corresponding sequence were 50% (2/4), 36% (5/14) and 12% (1/8) in the in situ cancer, invasive cancer and non-cervical cancer tissues. No HSV was isolated from 7 cancer specimens which showed a positive reaction by nucleic acid hybridization.
HPV-DNA fragments were detected in biopsy specimens (29 cases of cancer of uterine cervix, 2 cervical dysplasia and 9 normal cervix) using DNA hybridization technique. It was demonstrated that 52% of biopsy specimens of the cancer of uterine cervix was positive for HPV 16 DNA probe, while 9% was positive for HPV 18 DNA probe. 11% of non-cancerous biopsy specimens had a positive result for HPV 16 DNA probe. It was also demonstrated that the positive rate of HPV 16 DNA was 75% in grossly cauliflower and nodular type tumors but only 25% in erosion type. It seems that the positive rate of HPV 16 DNA is correlated to gross appearance of the tumor. The positive rates of HPV 16 DNA were different in 6 provinces in China. It was 64% in Shanxi Province, a high incidence area but 36% in Sichuan Province, a low incidence area. These results suggest that the carcinogenesis of cancer of the uterine cervix, be related to HPV infection.
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Three male subjects were passively tilted from a supine to a 90 degree head-up standing position on 2 d each at 1 and 31 ATA, then on 1 d of the postdive period. On each day the subjects were tilted once in the morning (0800-1000) and once in the evening (2000-2200). Before each tilt experiment, the subjects were first intravenously cannulated for blood sampling, then assumed the supine position. A blood sample was taken after 10 min in the supine position, and another sample was taken after 15 min of motionless, supported standing. The plasma was analyzed for antidiuretic hormone (ADH), plasma renin activity (PRA), plasma cortisol, and aldosterone. ADH, PRA, and cortisol were significantly increased by tilt, but the responses varied with time of day or atmospheric pressure. Cortisol increased only in the morning tilt (P less than 0.005) and was not affected by pressure. At 1 ATA, PRA was elevated in the morning tilt experiment (P less than 0.005) and not the evening tilt, but the overall response to tilt was greater at 31 ATA than at 1 ATA (P less than 0.005). The ADH response to tilt (P less than 0.025) was unaffected by time of day, but was eliminated at 31 ATA. The basal levels of ADH were also lower at 31 ATA (P less than 0.005). The mechanism of these responses remains unclear, but the eliminated postural stimulation of ADH may account for the eliminated circadian excretory pattern of the hormones. The altered responses to body fluid shifts possibly contribute to the increased aldosterone and decreased ADH frequently observed at hyperbaria.
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Radioimmunoassay for parathyroid hormone (PTH) in equids was performed on blood samples from healthy equids and equids with hypercalcemia and hypophosphatemia. The assay was validated for equine carboxy-terminal PTH. Manipulation of serum ionized Ca in healthy equids by infusing Na2 EDTA and CaCl2 produced an expected increase and decrease, respectively, in measurable immunoreactive PTH. Intra-assay and interassay coefficients of variation were 2.6% and 11.7%, respectively. The range of PTH valves for healthy mature horse mares and geldings maintained on pasture was less than 0.27 ng/ml to 0.92 ng/ml and for horse colts fed grain was 0.61 to 1.25 ng/ml. Serum PTH values were measured on 2 equine patients with hypercalcemia, 1 pony with primary hyperparathyroidism and 1 horse with pseudohyperparathyroidism. Both patients had increased serum PTH values.
Pyran, when administered intravenously, enhanced antibody production in mice. The optimal dose seemed to be about 10 mg/kg body weight. Antibody titers of normal mice inoculated with pyran are usually 2 to 8 times higher than those of mice inoculated with normal saline. However, pyran does not affect antibody production significantly by oral administration or intraperitoneal inoculation. When mice are immunologically suppressed by cyclophosphamide and then receive antigen together with pyran, their antibody titers are as high as non-immunologically suppressed ones'. In other words, Pyran can relieve the immunosuppression exerted by cyclophosphamide. The finding suggests that Pyran may be of value in reducing microbial infection in patients who received immunosuppressive antineoplastic agents.