Postnatal hypoxemia increases angiotensin II sensitivity and up-regulates AT1a angiotensin receptors in rat carotid body chemoreceptors

In the present study, the effects of postnatal hypoxemia on the AT1 angiotensin receptor-mediated activities in the rat carotid body were studied. Angiotensin II (Ang II) concentration-dependently increased the chemoreceptor afferent activity in the isolated carotid body. Single- or pauci-fiber recording of the sinus nerve revealed that the afferent response to Ang II was enhanced in the postnatally hypoxic carotid body. To determine whether the increased sensitivity to Ang II is mediated by changes in the functional expression of Ang II receptors in the carotid body chemoreceptors, cytosolic calcium ([Ca2+]i) was measured by spectrofluorimetry in fura-2 acetoxymethyl ester-loaded type I cells dissociated from carotid bodies. Ang II (25-100 nM) concentration-dependently increased [Ca2+]i in the type I cells. The proportion of clusters of type I cells responsive to Ang II was higher in the postnatally hypoxic group than in the normoxic control (89 vs 66%). In addition, the peak [Ca2+]i response to Ang II was enhanced 2- to 3-fold in the postnatally hypoxic group. The [Ca2+]i response to Ang II was abolished by pretreatment with losartan (1 microM), an AT1 receptor antagonist, but not by PD-123177 (1 microM), an AT(2) antagonist. Double-labeling immunohistochemistry confirmed that an enhanced immunoreactivity for AT1 receptor was co-localized to the lobules of type I cells in the hypoxic group. In addition, RT-PCR analysis of subtypes of AT1 receptors showed an up-regulation of AT1a but a down-regulation of AT1b receptors, indicating a differential regulation of the expression of AT1 receptor subtypes by postnatal hypoxia in the carotid body. These data suggest that postnatal hypoxemia is associated with an increased sensitivity of peripheral chemoreceptors in response to Ang II and an up-regulation of AT1a receptor-mediated [Ca2+]i activity of the chemoreceptors. This modulation may be important for adaptation of carotid body functions in the hypoxic ventilatory response and in electrolyte and water homeostasis during perinatal and postnatal hypoxia.

Life threatening acute epiglottitis in acute leukemia

We report an 8-year-old boy who developed a life-threatening acute epiglottitis during induction chemotherapy for acute promyelocytic leukemia. He survived the infection with emergency tracheostomy, treatment with broad spectrum antibiotics and amphotericin, and the use of granulocyte-macrophage colony stimulating factor. No organism was identified. A literature review identified 18 cases of acute epiglottitis in cancer patients. Sixteen of them were suffering from hematologic malignancies and three patients had received bone marrow transplantation. Unlike the usual case of epiglottitis, the majority (15 out of 18) of affected patients were adults and none of the infections was associated with Haemophilus influenzae. Streptococcus pneumoniae and Candida albicans were the most frequently identified pathogens. Early recognition and aggressive supportive care are required for successful management.

Local regulation of anion secretion by pituitary adenylate cyclase-activating polypeptide in human colonic T84 cells

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a novel hypothalamic peptide, which has been shown to exert various functions in a number of tissues, including exocrine and endocrine tissues. The present study investigated the role of local PACAP in the control of anion secretion by the human colonic T84 cell. Both bioactive forms of PACAP-27 and PACAP-38 gave rise to a dose-dependent increase in the short-circuit current (I(SC)). However, there was a reversal in the order of potency observed at different concentration ranges for the two bioactive forms. PACAP-27 was greater than PACAP-38 when the peptide concentrations were below 10 n m; PACAP-38 was greater than PACAP-27 in the range of 10-80 n m. The effects of both PACAP forms were restricted to the apical aspect of the T84 cell. The I(SC)responses to both PACAP-27 and PACAP-38 were suppressed respectively by the non-selective Cl(-)channel blocker, diphenylamine-dicarboxylic acid (DPC), by the Ca(2+)dependent Cl(-)channel blocker, diisothiocyanatostilbene-disulfonic acid (DIDS) and by the Ca(2+)chelator, BAPTA-AM, indicating the involvement of Ca(2+). The expression of PACAP was demonstrated and localized specifically to the perinuclear cytoplasm of the T84 cell using immunocytochemistry, indicating its epithelial origin. Thus, the present data suggest that, in addition to the well-known cAMP-dependent pathway, PACAP may play a role in regulating colonic Cl(-)secretion via a Ca(2+)-dependent pathway, perhaps through two distinct PACAP receptor subtypes. Moreover, the regulation of anion secretion by T84 cells may be mediated by locally formed PACAP in an autocrine or paracrine fashion.

Functional expression of angiotensin II receptors in type-I cells of the rat carotid body

Angiotensin II increases afferent discharge from the carotid body in vitro. We hypothesized that angiotensin II receptors (AT receptors) are expressed functionally in the type-I cell of the carotid body. Cytosolic free [Ca2+] ([Ca2+]i) in type-I cells freshly dissociated from rat carotid bodies was measured spectrofluorimetrically. Angiotensin II (10-100 nM) concentration-dependently increased [Ca2+]i in type-I cells. The [Ca2+]i response was blocked by pretreatment with losartan (1 microM), an AT1 receptor antagonist, but not by blockade of AT2 receptors with PD- 123319 (1 microM). Moreover, the gene expression of AT1 receptors was assessed by the reverse transcriptase polymerase chain reaction and gene transcripts of both AT1a and AT1b receptors were detected in the carotid body. In addition, immunohistochemical study revealed that AT1 immunoreactivity was localized in lobules of type-I cells in the carotid body. Taken together, these results suggest that type-I cells in the rat carotid body express functional angiotensin II receptors. The binding of angiotensin II to the AT1 receptors increases [Ca2+]i, a key step of the intracellular signalling cascade following the activation of the receptors. It is concluded that angiotensin II modulates carotid body chemoreceptor function directly via AT1 receptors in the type-I cell.

Chronic hypoxia upregulates the expression and function of AT(1) receptor in rat carotid body

In the present study, the effects of chronic hypoxia on the expression and localization of angiotensin II (Ang II) receptors are investigated by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) and by immunohistochemistry. The effect of chronic hypoxia on the carotid body chemoreceptor activity was also examined by in vitro electrophysiology. Results from RT-PCR revealed that chronic hypoxia exhibited differential effects on the gene expression of Ang II receptors, namely AT(1) and AT(2), in the carotid body. The mRNA expression for subtypes of the AT(1) receptor, AT(1a) and AT(1b), was significantly increased in the carotid body with chronic hypoxia. To further investigate the localization of the AT(1) receptor, an immunohistochemical study was performed. The results showed that AT(1) receptor immunoreactivity was found in lobules of glomus cells in the carotid body and the immunoreactivity was more intense in chronic hypoxia than in normoxic controls. In vitro electrophysiological studies consistently demonstrated that chronic hypoxia enhanced the AT(1) receptor-mediated excitation of carotid body chemoreceptor activity. These data suggest that chronic hypoxia upregulates the transcriptional and post-transcriptional expression of AT(1) receptors in the rat carotid body. The upregulation of the expression also enhances AT(1) receptor-mediated excitation of the carotid body afferent activity. This might be important in the modulation of cardiorespiratory functions as well as fluid and electrolyte homeostasis during chronic hypoxia.

Testicular hormonal regulation of the renin-angiotensin system in the rat epididymis

Evidence for the existence of an intrinsic angiotensin system based on locally formed angiotensinogen as a precursor for angiotensin production has been demonstrated in the rat epididymis. The data strongly support the presence of an epididymal renin-angiotensin system (RAS) which may be important for epididymal and sperm functions. In the present study, the effects of castration and testicular hormonal replacement on the expression of RAS components from the rat epididymis are investigated at the gene and protein levels. Results from northern blot and western blot analyses consistently showed that the expression of angiotensinogen mRNA and protein was apparently abolished by castration whereas their expression was completely restored to control levels when the castrated rats were hormonally replaced with either testosterone alone or with combined testosterone and estradiol. Northern blot did not detect any signal for angiotensinogen mRNA while western blot could detect a weak signal for angiotensinogen protein when the castrated rats were replaced with estradiol alone. Renin could be detected neither in control, castrated nor hormonally replaced rats. Moreover, the expression of angiotensin II receptor, type I (AT1) was almost abolished by castration as demonstrated by northern blot and reverse transcription-polymerase chain reaction. These data indicate that the expression of RAS by the rat epididymis at the levels of its precursor angiotensinogen and its receptor AT1, is subject to the regulation of testicular hormones and its expression appears to be predominantly testosterone-dependent.

Ammonia clearance by peritoneal dialysis and continuous arteriovenous hemodiafiltration

We report the use of continuous arteriovenous hemodiafiltration (CAVHD) in a neonate with severe hyperammonemia due to a urea cycle disorder. We compared the ammonia clearance (C(NH3)) for peritoneal dialysis (PD) and CAVHD. C(NH3) for CAVHD was 7.45 ml/min per m2 at a dialysate flow of 300 ml/h and was 10.55 ml/min per m2 at a dialysate flow rate of 600 ml/h. The mean PD clearance was 2.15 ml/min per m2. Our data suggest that CAVHD is superior to PD for the removal of plasma ammonia. We conclude that CAVHD should be considered a reasonable alternative in the treatment of neonatal hyperammonemia in urea cycle disorders when medical treatment fails.

Concurrent and independent HCO3- and Cl- secretion in a human pancreatic duct cell line (CAPAN-1)

The present study investigated both HCO-3 and Cl- secretions in a human pancreatic duct cell line, CAPAN-1, using the short-circuit current (Isc) technique. In Cl-/HCO-3-containing solution, secretin (1 microM) or forskolin (10 microM) stimulated a biphasic rise in the Isc which initially reached a peak level at about 3 min and then decayed to a plateau level after 7 min. Removal of external Cl- abolished the initial transient phase in the forskolin-induced Isc while the plateau remained. In HCO-3/CO2-free solution, on the contrary, only the initial transient increase in Isc was prominent. Summation of the current magnitudes observed in Cl--free and HCO-3-free solutions over a time course of 10 min gave rise to a curve which was similar, both in magnitude and kinetics, to the current observed in Cl-/HCO-3-containing solution. Removal of external Na+ greatly reduced the initial transient rise in the forskolin-induced Isc response, and the plateau level observed under this condition was similar to that obtained in Cl--free solution, suggesting that Cl--dependent Isc was also Na+-dependent. Bumetanide (50 microM), an inhibitor of the Na+-K+-2Cl- cotransporter, and Ba2+ (1 mm), a K+ channel blocker, could reduce the forskolin-induced Isc obtained in Cl-/HCO-3-containing or HCO-3-free solution. However, they were found to be ineffective when external Cl- was removed, indicating the involvement of these mechanisms in Cl- secretion. On the contrary, the HCO-3-dependent (in the absence of external Cl-) forskolin-induced Isc could be significantly reduced by carbonic anhydrase inhibitor, acetazolamide (45 microM). Basolateral application of amiloride (100 microM) inhibited the Isc; however, a specific Na+-H+ exchanger blocker, 5-N-methyl-N-isobutylamiloride (MIA, 5-10 microM) was found to be ineffective, excluding the involvement of the Na+-H+ exchanger. However, an inhibitor of H+-ATPase, N-ethylmaleimide did suppress the Isc (IC50 = 22 microM). Immunohistochemical studies also confirmed the presence of a vacuolar type of H+-ATPase in these cells. H2DIDS (100 microM), an inhibitor of Na+-HCO-3 cotransporter, was without effect. Apical addition of Cl- channel blocker, diphenylamine-2,2'-dicarboxylic acid (DPC, 1 mm), but not disulfonic acids, DIDS (100 microM) or SITS (100 microM), exerted an inhibitory effect on both Cl- and HCO-3-dependent forskolin-induced Isc responses. Histochemical studies showed discrete stainings of carbonic anhydrase in the monolayer of CAPAN-1 cells, suggesting that HCO-3 secretion may be specialized to a certain population of cells. The present results suggest that both HCO-3 and Cl- secretion by the human pancreatic duct cells may occur concurrently and independently.

Nodular histiocytic/mesothelial hyperplasia: a lesion potentially mistaken for a neoplasm in transbronchial biopsy

This report describes two examples of nodular histiocytic/ mesothelial hyperplasia as seen in transbronchial biopsy that initially led to serious consideration of neuroendocrine neoplasm or meningioma. The biopsies showed nodular collections of cohesive polygonal or round cells with ovoid or deeply grooved nuclei and a moderate amount of finely granular cytoplasm. Nuclear pleomorphism was mild. Immunohistochemical studies showed few cells staining for cytokeratin and the mesothelial marker HBME-1, whereas most cells were decorated by the histiocytic marker PG-M1 (CD68). This lesion appears to be identical to nodular mesothelial hyperplasia as described in hernia sacs and mesothelial/monocytic incidental cardiac excrescences, and we propose modifying the designation to "nodular histiocytic/mesothelial hyperplasia" to take into account the marked predominance of histiocytes over mesothelial cells. The clues to recognition of the true nature of the lesion are clinicopathologic correlation and identification of strips of low cuboidal (mesothelial) cells in the vicinity, and the diagnosis can be further confirmed by immunohistochemical staining. Nodular histiocytic/mesothelial hyperplasia probably results from irritation to the mesothelial lining by various causes leading to focal aggregation of histiocytes within retraction pockets or crevices of the serosal cavity.

Evaluation of a histogenetic classification for thymic epithelial tumours

We reviewed 87 thymic epithelial tumours from Chinese patients and typed them according to the Marino and Müller-Hermelink classification as updated by Kirschner and Müller-Hermelink in 1989. Related categories were grouped for statistical analyses: group 1, medullary thymoma and mixed thymoma; group 2, cortical predominant thymoma; group 3, cortical thymoma and well-differentiated thymic carcinoma; group 4, other thymic carcinomas; and group 5, unclassified. Group 3 tumours were more frequently associated with the myasthenia gravis syndrome compared with group 1 tumours (P = 0.001). They also presented at a more advanced stage. Groups 1 and 2 showed an excellent prognosis (100% survival at 10 years). The 10-year survival for groups 3 and 4 patients was 40% and 30% respectively. Pure medullary thymoma made up a higher proportion of our cases (10.3%) than those of a similar Caucasian study (5.3%). The eight thymic carcinomas (group 4) included two thymic lymphoepitheliomas. We conclude that the histogenetic classification evaluated shows a clear correlation with prognosis and clinical features, even when tested on separate geographic groups, where pathogenetic factors may be different. A common approach to classification of thymic epithelial tumours would greatly facilitate future studies on these possible differences.

Hepatitis C virus antibody in multiply transfused Chinese with thalassaemia major

Thirty-four of 99 multiply transfused Chinese (49 females, 50 males) with thalassaemia major were positive for antibody to hepatitis C virus. There was no sex predominance in seropositivity with 18 females and 16 males positive. The mean (+/- SD) age and units of blood transfused were significantly higher in the seropositive patients (167 +/- 48 months, 206 +/- 82 units respectively) than the seronegative patients (113 +/- 56 months, 124 +/- 80 units respectively). The seropositive patients had higher mean (+/- SD) serum alanine aminotransferase, aspartate aminotransferase and ferritin concentrations (91 +/- 82 IU/L, 67 +/- 38 IU/L, 4797 +/- 2522 ng/ml respectively) than the seronegative patients (38 +/- 29 IU/L, 48 +/- 28 IU/L, 3620 +/- 2140 ng/ml respectively). Serum ferritin had an independent and significant effect on serum alanine aminotransferase in addition to that of seropositivity to hepatitis C virus.

Factors affecting fetal loss in induction of ovulation with gonadotropins: increased abortion rates related to hormonal profiles in conceptual cycles

Thirty-six first-trimester abortions (9.7%), 16 second-trimester abortions (4.3%), 11 ectopic pregnancies (2.9%), and 10 stillbirths (2.7%) occurred in 373 conceptual cycles after gonadotropin induction of ovulation. Fetal wastage was higher in spontaneous pregnancies that occurred before therapy (54.3%, p less than 0.0001) and lower with subsequent spontaneous pregnancies (10.1%, p less than 0.05). Significant risk factors for overall fetal loss during induced ovulation were a continuous rise of estrogen excretion until ovulation (p less than 0.01) and previous abortion (p less than 0.05). For first-trimester abortion, the risk factor was continuous estrogen rise (p less than 0.01); for second-trimester abortion, the risk factors were a low luteal pregnanediol-to-estrogen excretion ratio (p less than 0.002), increased age at conception (p less than 0.02), and high baseline estrogen excretion (p less than 0.05). Multiple pregnancy was not significant. The continuous rising estrogen pattern may serve as a marker of abnormal oocyte maturation. We propose that future studies on infertility treatment should report on pregnancy outcome.

Treatment-independent pregnancies after cessation of gonadotropin ovulation induction in women with oligomenorrhea and anovulatory menses

Life-table analysis was performed for the cumulative spontaneous pregnancy rate (CSPR) of 56 patients with oligomenorrhea and anovulatory cycles who had been treated with gonadotropin for ovulation induction between 1963 and 1985. Twenty-seven had at least one spontaneous pregnancy, giving rise to a CSPR of 66.4% (95% confidence limit [CL] 42.4% to 90.4%) at 115 months for the first spontaneous pregnancy, which is significantly lower than the cumulative induced pregnancy rate (CIPR) of 88.6% at 23 months for the first course of gonadotropin therapy (P less than 0.0001). This fertility potential was not affected by the baseline estrogen and follicle-stimulating hormone levels, diagnosis, result of gonadotropin therapy, and age and menstrual pattern during exposure to spontaneous pregnancy by Cox regression analysis. More multiple births occurred in the induced pregnancies than in the spontaneous pregnancies (P = 0.005).

Outcome of patients with one ovary in an in vitro fertilization program

To determine whether the absence of one ovary would influence adversely the outcome of in vitro fertilization, the results of 60 laparoscopic oocyte retrieval procedures in 34 single-ovary patients were compared with the outcome for all laparoscopic retrieval cycles during the same period (January 1984-August 1986) in patients with tubal infertility and two accessible ovaries (559 cycles in 335 patients). The median age was younger in the one-ovary group (31 vs 32) (P less than 0.05). The group with two accessible ovaries had significantly more follicles aspirated (median, 7 vs 5; P less than 0.001) and more oocytes obtained (median, 5 vs 4; P less than 0.001) per retrieval compared with the single-ovary group. However, the single-ovary group had a higher percentage fertilization (69 vs 62%; P less than 0.05) so that the number of embryos transferred per transfer patient (median, 3 vs 3) and pregnancy rate per cycle (9.7 vs 15.6%) did not differ significantly between groups. We conclude that patients with a single ovary have a compensatory increase in the ability to produce oocytes which may have greater potential for fertilization and subsequent development.

Smoking, passive smoking and histological types in lung cancer in Hong Kong Chinese women

In a case control study in Hong Kong, 445 cases of Chinese female lung cancer patients all confirmed pathologically were compared with 445 Chinese female healthy neighbourhood controls matched for age. The predominant histological type was adenocarcinoma (47.2%). The relative risk (RR) in ever-smokers was 3.81 (P less than 0.001, 95% CI = 2.86, 5.08). The RRs were statistically significantly raised for all major cell types with significant trends between RR and amount of tobacco smoked daily. Among never smoking women, RR for passive smoking due to a smoking husband was 1.65 (P less than 0.01, 95% CI = 1.16, 2.35) with a significant trend between RR and amount smoked daily by the husband. When broken down by cell types, the numbers were substantial only for adenocarcinoma (RR = 2.12, P less than 0.01, 95% CI = 1.32, 3.39) with a significant trend between RR and amount smoked daily by the husband. The results suggest that passive smoking is a risk factor for lung cancer, particularly adenocarcinoma in Hong Kong Chinese women who never smoked.

Mild to moderate abnormalities of semen do not affect pregnancy rates during ovulation induction with gonadotrophins

One or more semen analysis results were available for 195 men whose wives responded to ovulation induction with gonadotrophins performed at The Royal Women's Hospital since 1963. Fifty-three men (27%) has subnormal semen analyses by conventional criteria: sperm concentration less than or equal to 20 X 10(6)/ml, motility less than or equal to 40% or normal morphology less than or equal to 50%. The lifetable pregnancy rates were not significantly different for those with subnormal and normal semen (chi 2 = 0.169), by six cycles 64% (s.e.m. = 7) with subnormal semen had conceived compared with 59% (s.e.m. = 5) with normal semen. It appears that lower limits of semen quality could be relaxed for women needing ovulation induction with gonadotrophins.