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Biomedical subjects

C Wang

Publications and source records attributed to C Wang.

At least 1,225 records · Page 68Linked to original sources

The responses of pollen to applied electrical fields.

The growing pollen tubes of tomato and tobacco were exposed to electrical fields and the effect on the direction of growth was measured. They responded by turning toward the positive electrode (anode) and gave a detectable response in fields as small as 0.1 mV/tube diameter. The sites of germination of tobacco pollen grains were also affected by applied fields; the pollen tubes tended to emerge from the anodal side. This effect was detectable at a field of 0.4 mV/grain diameter.

Electricity↗

Intrauterine insemination is not useful in oligoasthenospermia.

A prospective randomized study was conducted in 47 couples with infertility due to subnormal semen to compare luteinizing hormone (LH)-timed intrauterine insemination with LH-timed natural intercourse. No pregnancy occurred in 114 cycles of intrauterine insemination with washed sperm. Only one patient conceived during 1 of the 124 natural intercourse cycles. The only complication that occurred after intrauterine insemination was mild abdominal cramp in 3 cycles. The authors conclude that intrauterine insemination is not useful in the management of subfertility due to oligoasthenospermia.

Adult↗

Imaging for adrenal tumours.

Modern medical imaging has transformed the diagnosis and management of adrenal disease. The various types of adrenal tumours bear different aspects of problems in diagnostic imaging. The investigation used must be determined and monitored individually, as directed by the clinical and biochemical findings. CT plays a central role in the localization of the functioning adrenal tumours. It is regarded as the imaging modality of choice because it combines safety with a high rate of detection. It is highly sensitive in the localization of the large adrenal tumours that account for Cushing's syndrome and phaeochromocytomas, as well as the small tumours that account for primary hyperaldosteronism. It is, however, not reliable for the detection of adrenal hyperplasia, and does not yield functional imaging information. For small tumours not detectable by CT, and for ectopic tumours, complementary investigations with appropriate application of venous sampling, radionuclide scintigraphy and occasionally arteriography, will be very useful. CT-guided percutaneous biopsy is employed for the incidentalomas in oncologic patients. MRI appears to hold a great potential for the diagnosis of adrenal disorders, but this modality is awaiting wider availability of instrumentation and clearer documentation of techniques.

Adrenal Gland Neoplasms↗

Immunophenotypic and gene probe analysis of a case of Richter's syndrome.

A rare case of diffuse large cell lymphoma (DLL) arising in the stomach of a patient with long-standing chronic lymphocytic leukemia (CLL) has been examined by a combination of immunophenotypic and gene probe methods. Both the resected lymphoma and the CLL (obtained from an infiltrate in perigastric lymph nodes) expressed surface membrane markers consistent with a B-cell origin (HLA-DR+; B1+; B4+), but surface membrane immunoglobulin (SmIg) could be detected only on the CLL cells (SmIgM lambda+). Neither neoplasm expressed cytoplasmic immunoglobulin. DNA probe analysis using the Southern blot method and probes to the joining (J-H) region of the immunoglobulin heavy chain gene and to the constant (C) regions of the immunoglobulin kappa and lambda light chain genes revealed different light and heavy chain gene rearrangements in the two neoplasms. These findings suggest that the large cell lymphoma arose from a different clone than the CLL and the development of large cell lymphoma may have represented a de novo neoplastic event in a predisposed person.

Antigens, Neoplasm↗

Computer-assisted image analysis of sperm concentration in human semen before and after swim-up separation: comparison with assessment by haemocytometer.

Evaluation of male fertility is based predominantly on results from semen analysis and determination of the sperm concentration is one of the main parameters of the analysis. The availability of a fully automated videomicrographic digital image analyser would offer both an objective and rapid method for determination of the sperm concentration. In the present study the sperm concentration in 327 semen samples was determined by haemocytometer according to the World Health Organization guidelines, and also by a computer-assisted digital image analyser system. Results were classified according to the routine procedure (haemocytometer) before statistical analyses. The computerized measurements caused a shift to the right in the frequency distribution of sperm concentration. Sperm concentrations were more often overestimated significantly (P less than 0.001) by the computerized measurements in semen samples with concentrations up to 80.0 x 10(6)/ml. This overestimation seemed to be caused by the presence of particles in seminal plasma that were recognized incorrectly as sperm by the computer program. The computerized digital image analyser gave an average sperm concentration of 2.2 +/- 0.6 x 10(6)/ml (mean +/- SEM) in 17 azoospermic semen samples while the routine procedure did not detect the presence of sperm cells. After removing the seminal plasma by washing and centrifugation with culture medium, and using the swim-up procedure to harvest motile sperm, the computerized measurements showed comparable results with the routine procedure for those sperm preparations (n = 44) with sperm concentrations greater than 5.0 x 10(6)/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗

Treatment of precocious puberty using an intranasal luteinizing hormone-releasing hormone analogue: Buserelin.

Fourteen patients with precocious puberty were treated for 1-3 years with 900-1800 micrograms/day of intranasal (i.n.) Buserelin. The peak luteinizing hormone and follicle-stimulating hormone responses to intravenous luteinizing hormone-releasing hormone were reduced significantly 4 weeks after starting treatment and remained suppressed while the patients were on treatment. Two patients were withdrawn because of drug non-compliance. Three patients showed regression of pubertal changes, four patients showed no progression and five patients showed progression of breast size or pubic hair staging after 1.5-2 years of treatment. Treatment was changed to the subcutaneous route in two patients because of hormonal escape and accelerated skeletal maturation. The mean growth velocity decreased from 10.78 cm/year (s.e.m. = 0.64) to 7.06 cm/year (s.e.m. = 0.85) after 1 year of treatment (P less than 0.005). After an increase in dosage (from 900 micrograms/day to 1800 micrograms/day) in most patients, further significant falls in growth velocity to 5.29 cm/year (s.e.m. = 0.45), 4.63 cm/year (s.e.m. = 0.8) and 5.06 cm/year (s.e.m. = 0.5) were observed at 18, 24 and 30 months, respectively, compared with the pretreatment value (P less than 0.001). With treatment, the increased rate of skeletal maturation normalized. In 10 patients who had completed 2 years of treatment, the height standard deviation score for bone age improved from a pretreatment value of -2.42 +/- 0.42 to -1.6 +/- 0.42 after 2 years of treatment (P less than 0.01), indicating an improvement in height prognosis. It is concluded that i.n. Buserelin at a dose of 1800 micrograms/day is effective in the treatment of most but not all patients with precocious puberty.

Administration, Intranasal↗

Long-term effects of megavoltage radiotherapy in acromegaly.

The progress of 41 Chinese patients with acromegaly treated with megavoltage radiotherapy was reviewed after a mean follow-up of 4.5 (one-ten) years. Nine received prior surgery. Radiotherapy was delivered by a 3-field technique to a total of 4000-5000 cGy in 25 fractions. By life table analysis successful treatment of growth hormone (GH) hypersecretion, as defined by a mean GH concentration of less than or equal to 10 mu/L, could be expected in 6, 11, 26, 64 and 67% of the patients after one, two, five, eight and ten years respectively. Median intervals before achieving a mean GH level of less than or equal to 10 mu/L were 6.6 and 8.6 years following radiotherapy with the higher (4500-5000 cGy) and lower (4000 cGy) doses respectively, suggesting a tendency towards earlier response following radiotherapy with the higher dose. The prevalence of acquired hypopituitarism in patients followed up for over five years was 40% for gonadotrophins, 30% for TSH and 20% for ACTH deficiency respectively. In the majority of patients, acquired hypopituitarism was not apparent within five years after radiotherapy. No mortality or major side effects were noted following radiotherapy. In 34 patients on long-term bromocriptine treatment, mean GH concentrations were normalised in 26.5% of patients. We conclude that with judicious selection of patients and use of adjunctive medical therapy, megavoltage radiotherapy remains a safe and satisfactory form of treatment for acromegaly especially if expert transphenoidal surgery is not readily available.

Acromegaly↗

Erythrocyte sodium-potassium pump in thyrotoxic periodic paralysis.

To search for a genetic marker in patients with thyrotoxic periodic paralysis (TPP), we studied the erythrocyte sodium-potassium pump activity in 13 patients with TPP; 30 thyrotoxic patients with no history of paralysis (T) and 69 euthyroid controls. In thyrotoxic patients (TPP and T), erythrocyte ouabain binding and ouabain sensitive sodium efflux rate constant were decreased while erythrocyte sodium content was increased. All these changes reverted to normal when the patients became euthyroid. Maximal ouabain binding capacity correlated positively with ouabain sensitive sodium efflux rate constant (r = 0.542; p less than 0.001; n = 155) and negatively with serum thyroxine concentration (r = -0.571; p less than 0.001; n = 60) and erythrocyte sodium content (r = -0.521; p less than 0.001; n = 155). In the thyrotoxic state, maximal ouabain binding capacity was just significantly higher in TPP when compared with T (0.268 +/- 0.014 and 0.234 +/- 0.009 pmol/10(9) cells respectively; p less than 0.05). This difference could not be demonstrated when the patients became euthyroid. Our findings suggest that patients with TPP respond to thyrotoxicosis with a smaller decrement in erythrocyte sodium-potassium ATPase activity than patients without a history of paralysis. However, the difference is too small to represent a useful genetic marker for this disease entity

Erythrocytes↗

Complement phenotypes in patients with psoriasis.

Phenotype frequencies for the complement proteins C4A, C4B, Bf (factor B) and C3 were performed for 49 Caucasian patients with psoriasis. The C4*A6 allele was present in 26.6% of the patients as compared to 5.4% of healthy regional Caucasian controls, p less than 0.001, relative risk = 6.28. The C4*A6 allele is known to be in linkage disequilibrium with the HLA B17 allele and to produce a non-functional gene product when it occurs with the B17 allele. HLA B17 is known to be associated with psoriasis in many Caucasian populations. Additional findings in the present study were a significant reduction in the C4B*2 allele frequency, a non-significant increase in the Bf*F allele frequency and no difference for Bf or C3 phenotype frequencies in the patients with psoriasis as compared to the controls.

Complement C3↗

Gonadotropin-releasing hormone-dependent regulation of gonadotropin subunit messenger ribonucleic acid levels in the rat.

The Nal-Glu GnRH antagonist (GnRHA) was given to castrate male and female rats 7 days after gonadectomy to assess the impact of selective GnRH inhibition on the steady state mRNA levels of FSH beta, LH beta, and alpha-subunit and serum levels of FSH and LH. A low dose of GnRHA (125 micrograms/kg.day) given to female rats for 1, 3, or 7 days resulted in suppression of serum FSH and LH levels by 7 days to 50% and 40%, respectively, of ovariectomized control values. LH beta mRNA levels decreased in a time-dependent manner, so that by 7 days, LH beta mRNA levels were less than those in intact controls. There were significant but less dramatic declines in alpha and FSH beta mRNA levels. A higher dose of GnRHA (500 micrograms/kg.day) for 7 or 14 days administered to castrate male or female rats resulted in inhibition of serum LH and FSH to or below levels in intact controls. At this dose, all three gonadotropin subunit mRNA levels fell from castrate values toward or below those in intact controls. Thus, although low dose GnRHA administration suppressed LH beta mRNA more than FSH beta mRNA levels, high dose GnRHA treatment resulted in equal suppression of all three gonadotropin subunits. No stimulatory effects on alpha-subunit mRNA levels were observed with either dose of GnRHA. We conclude that the pretranslational control of gonadotropin subunit biosynthesis is GnRH dependent. Adequate dose and length of administration of the potent Nal-Glu GnRHA results in suppression of both the serum gonadotropins FSH and LH and the mRNAs for FSH beta, LH beta, and alpha-subunit in female and male rats.

Animals↗

Glucocorticoids stimulate plasminogen activator production by rat granulosa cells.

We studied the direct effects of glucocorticoids on plasminogen activator (PA) production by rat granulosa cells. PA production was assayed by culturing rat granulosa cells on [125I]fibrin plates and determining the extent of fibrinolysis after addition of the specific substrate plasminogen. In granulosa cells from preantral follicles of immature rats, treatment with FSH caused dose-dependent increases in PA production whereas glucocorticoids by itself was without effect. Increasing concentrations (10(-10) to 10(-6) M) of both natural and synthetic glucocorticoids potentiated the stimulating effect of FSH on PA production by 120 to 170%. The stimulatory potencies of the natural corticosteroids correlated with the glucocorticoid potencies (cortisol/corticosterone greater than aldosterone/11-deoxycorticosterone). In granulosa cells from Graafian follicles of mature rats, glucocorticoids on its own had direct stimulating effect on PA production. The stimulatory action of glucocorticoids on FSH-dependent PA production was completely blocked by simultaneous treatment with antiglucocorticoid RU 486. Antiserum directed against tissue-type PA (tPA) neutralized the increased fibrinolytic actions of glucocorticoids. Using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fibrin autography techniques, we showed that the increase in fibrinolytic activity in response to glucocorticoids resulted from increased production of tPA rather than urokinase-like PA. The effect of glucocorticoids on the production of PA inhibitors (PAI) was examined by 1) neutralization of urokinase activity by increasing amounts of culture media from granulosa cells treated with glucocorticoids, 2) reverse fibrin autography, and 3) Western blot analysis with a specific PAI antiserum. All these methods failed to detect a stimulatory action of glucocorticoids, with or without FSH, on PAI production by rat granulosa cells in the culture media. Our data showed that glucocorticoids have a direct stimulating effect on tPA production, but unlike its action on other in vitro systems, they have no significant effect on PAI production by rat granulosa cells in vitro.

Animals↗

The effect of altered thyroid status on pituitary hormone messenger ribonucleic acid concentrations in the rat.

To study the effects of altered thyroid status on pretranslational control of pituitary hormones, adult male rats were given propylthiouracil for 6 weeks and underwent the following studies. 1) Rats were injected with T3 at 10 micrograms/100 g BW daily for 10 days. 2) Rats were given T3 injections at 0, 0.01, 0.1, 1.0, or 10 micrograms/100 g BW for 10 days. 3) Rats were killed 0, 1, 6, or 24 h after a single injection of T3 at 10 micrograms/100 g BW or after 5 or 10 days of daily T3 injections. Pituitary mRNA concentrations of TSH beta, alpha-subunit, PRL, GH, POMC, FSH beta, and LH beta were determined for individual animals. Marked increases in TSH beta and alpha-subunit mRNAs occurred after PTU treatment, and these changes were reversed by 1.0 microgram/100 g BW T3 and within 24 h of a single T3 injection of 10 micrograms/100 g BW. Further increases in the dose or time course of T3 administration led to a relatively greater suppression of TSH beta mRNA levels than alpha-subunit mRNA levels. In contrast, GH and PRL mRNA levels were low in hypothyroid animals, and both rose toward control levels with 0.1 microgram/100 g BW T3 and by 24 h after a single T3 dose. Induction of hyperthyroidism did not further increase GH mRNA levels above control, but increased PRL mRNA levels 2-fold over control. No changes were seen in FSH beta, LH beta, or POMC mRNA levels with any treatment. Thus, studies of altered thyroid status in the rat reveal dose-response and time-course variability in the pretranslational control of TSH beta, alpha-subunit, GH, and PRL by thyroid hormone.

Animals↗

Hypogonadotropic hypogonadism in severe beta-thalassemia: effect of chelation and pulsatile gonadotropin-releasing hormone therapy.

We studied pituitary-gonadal function in 11 male and 5 female patients, aged 12-30 yr, with severe beta-thalassemia and chronic iron overload. All had normal basal serum cortisol, T4, and PRL concentrations and normal serum cortisol and GH responses to insulin-induced hypoglycemia and TSH responses to TRH. Of the 11 male patients (all over 17 yr of age), only 3 attained full pubertal development and 4 had subnormal serum LH and FSH responses to GnRH. As a group, their mean basal serum testosterone (T) level was low [11.7 +/- 4.9 (+/- SE) nmol/L; normal, 10-40 nmol/L], and 9 of the 11 male patients responded to hCG with a rise in serum T. Two of the 3 female patients over 17 yr of age were prepubertal with undetectable serum estradiol (E2) levels and absent serum LH and FSH responses to GnRH; the other female patient had regular menstrual cycles and normal serum E2 levels and LH and FSH responses to GnRH. Six of the prepubertal patients (4 males and 2 females, aged 17-30 yr) were studied serially for 3 yr after the start of chelation therapy. Despite a fall of median serum ferritin from 11,910 to 1,303 pmol/L, there was no progression of puberty, and their basal and GnRH-stimulated serum LH and FSH and serum T or E2 levels did not change. Three of these patients (1 male and 2 female) then received pulsatile sc GnRH therapy in addition to chelation therapy for 6 months with no improvement. We conclude that chronic iron overload in patients with severe thalassemia leads to variable degrees of hypogonadotropic hypogonadism, which do not respond to chelation therapy given late in the course of the disease. The hypogonadism in most patients was due to pituitary hyporesponsiveness to GnRH.

Adolescent↗

Comparison of the effectiveness of 2-hourly versus 8-hourly subcutaneous injections of a somatostatin analog (SMS 201-995) in the treatment of acromegaly.

To determine whether sc injections of a somatostatin analog (SMS 201-995) every 2 h (q2h) is more effective than sc injections every 8 h (q8h) in achieving a constant suppression of GH levels and a more satisfactory clinical response, we studied 10 patients with acromegaly (4 newly diagnosed and 6 previously treated with bromocriptine/pituitary irradiation/transfrontal hypophysectomy). The dose of SMS 201-995 was increased from 300 micrograms/day to a maximum of 600 micrograms/day when the mean serum GH (hourly samples for 12 h) failed to be suppressed to undetectable levels in over 75% of the samples. Five patients received a 200-micrograms sc injection q8h (600 micrograms/day), and the other 5 received sc injections q2h [418 +/- 46 micrograms/day (mean +/- SE); range, 288-504 micrograms/day]. In the group receiving q2h sc SMS 201-995 there was a marked suppression of mean GH from a basal level of 77.3 +/- 24.7 mU/L to less than 5 mU/L in all five subjects. In the group receiving q8h sc SMS 201-995, mean GH was suppressed from a basal level of 82.2 +/- 21.7 to 15.4 +/- 3.3 mU/L after 6 months of therapy, and none of the patients had a mean GH level consistently less than 5 mU/L. Despite the difference in the level of GH suppression, mean serum somatomedin-C levels were decreased promptly in both groups of subjects. Associated with the decrease in somatomedin-C levels there was a marked clinical response in both groups, but improvement in clinical features and decreases in hand volumes and ring size occurred earlier in the group receiving SMS 201-995 q2h. Significant tumor shrinkage (25% to greater than 50% reduction) was observed in two patients receiving q2h injections, while a 25-50% reduction in tumor size was noted in another patient receiving q8h injections. Because of the small doses of SMS 201-995 used side-effects of abdominal discomfort and flatulence were mild and rapidly disappeared. Our results show that increasing the frequency of sc administration of the somatostatin analog from q8h to q2h leads to more marked and consistent suppression of GH levels and more rapid improvement of clinical signs. Increasing the frequency of delivery of SMS 201-995 may be an alternative to increasing the dose in some patients with acromegaly.

Acromegaly↗

The expression of the proto-oncogene C-kit in the blast cells of acute myeloblastic leukemia.

The oncogene kit has been shown genetically to map in the W locus of the mouse. This locus is known to have an important role in the regulation of normal hemopoietic stem cell growth. The blast cells of acute myeloblastic leukemia may be considered to arise in predeterministic stem cells. Accordingly, we sought evidence that kit was involved in the regulation of AML blast growth, using a cDNA probe to the external domain of c-kit. With this probe the gene was found to be in germline configuration in blast cells from AML, ALL, and continuous myeloblastic cell lines. However, expression could be detected by Northern analysis or RNA dot blots only in fresh AML blast cells. Fresh cells from ALL patients, normal bone marrow, PHA-stimulated lymphocytes, and four myeloblastic continuous cell lines were expression negative by the same techniques.

DNA↗