Effects of the bovine SLICK1 mutation in PRLR on sweat gland area, FOXA1 abundance, and global gene expression in skin

The SLICK1 mutation in the prolactin receptor (PRLR) results in a short-hair coat and increased ability to regulate body temperature during heat stress. It is unclear whether the mutation affects capacity for sweating. The objective of this observational study was to evaluate whether the SLICK1 mutation in PRLR alters characteristics of skin related to sweat gland abundance or function. Skin biopsies from 31 Holstein heifers, including 14 wild-type (SL^-/-) and 17 heterozygous slick (SL^+/-), were subjected to histological analysis to determine the percent of the surface area of skin sections that are occupied by sweat glands. We detected no effect of genotype on this variable. Immunohistochemical analysis of the forkhead transcription factor A1 (FOXA1), a protein essential for sweating in mice, from 6 SL^-/- and 6 SL^+/- heifers indicated twice as much FOXA1 in sweat glandular epithelia of SL^+/- heifers as in SL^-/- heifers. Results from RNA sequencing of skin biopsies from 5 SL^-/- and 7 SL^+/- heifers revealed few genes that were differentially expressed and none that have been associated with sweat gland development or function. In conclusion, results do not support the idea that the SLICK1 mutation changes the abundance of sweat glands in skin, but do show that functional properties of sweat glands, as indicated by increased abundance of immunoreactive FOXA1, are modified by inheritance of the mutation in PRLR.

[Clinical features and risk factors for early relapse of pediatric ulcerative colitis]

Objective: To investigate the clinical features of pediatric ulcerative colitis (UC) and analyze the risk factors of disease relapse. Methods: The clinical data of 79 children with UC diagnosed in Beijing Children's Hospital, Capital Medical University from January 2016 to February 2021 were retrospectively analyzed. They were divided into early relapse group and non-early relapse group according to the clinical relapse within 12 months after diagnosis. T-test, rank sum test, χ² test or Fisher's exact test were used to compare the variables between the 2 groups, including the clinical features, laboratory examination results and treatments. The Logistic regression was used to analyze the risk factors of early relapse. The cumulative relapse rate during follow-up was calculated by Kaplan-Meier method. Results: Among the 79 UC children, 46 were males and 33 were females, and the age of onset was 10.6 (6.4, 12.7) years. The children were mainly characterized by extensive disease (E3) and pancolitis (E4) (51/79, 65%), moderate to severe activity (48/79, 61%) and moderate to severe inflammation of colonic mucosa (71/79, 90%). Thirty-eight (48%) patients had atypical phenotype and 17 (22%) had extraintestinal manifestations. The follow-up period was 43.9 (22.8, 61.3) months, and of the 41 patients rechecked with colonoscopy, 7 (17%) had disease progression. According to Kaplan-Meier analysis, the cumulative relapse rate of the 79 cases at 3 months, 6 months, 1 year and 2 years after diagnosis were 27% (21/79), 47% (37/79), 57% (45/79) and 73% (53/73), respectively. There were 45 children (57%) in early relapse group and 34 (43%) in non-early relapse group. In early relapse group, hemoglobin and mucosal healing rate were both significantly lower (105 (87, 122) vs. 120 (104, 131) g/L, 28% (7/25) vs. 7/9, Z=-2.38, χ²=4.87, both P<0.05). The rate of steroid-dependent, E3 and step-up therapy during the induction period were all significantly higher than those in non-early relapse group (11/19 vs. 1/12, 24% (11/45) vs. 6% (2/34), 29% (13/45) vs. 6% (2/34), χ²=5.67, 4.85, 6.66, all P<0.05). Multivariate Logistic regression analysis showed that extraintestinal manifestations (OR=4.33, 95%CI 1.05-17.83), E3 (OR=8.27, 95%CI 1.47-46.46) and step-up therapy during the induction period (OR=5.58, 95%CI 1.01-30.77) were independent risk factors for early relapse. Conclusions: Pediatric UC is usually extensive and severe, with atypical phenotype, a high rate of relapse and a risk of disease progression. Extraintestinal manifestations, E3 and step-up therapy during the induction period are independent risk factors for early relapse.

[Epidemiological investigation of tinnitus in Sichuan and Chongqing]

Objectives: To investigate the prevalence and associated risk factors of tinnitus in Sichuan and Chongqing. Methods: We designed a tinnitus epidemiological questionnaire. The multi-stage stratified cluster random sampling methods was applied to obtain study subjects in six areas (Nanchong, Jiangjin, Fengdu, Yunyang, Suining and Ya'an), which were selected for epidemiological investigation. Home visit completion of epidemiological questionnaires was conducted. The trained investigators guided the respondents to fill in the tinnitus epidemiological questionnaires, and the epidemiological status of six areas on prevalence and risk factor was investigated. SPSS 22.0 software was used for statistical analysis. Results: Sampling population were 10 289, in which 9 273 were valid questionnaires. There were 4 281 males and 4 992 females, with an average age of 47.3 years, among which 34.83% (3 230/9 273) had tinnitus. 3.99% (370/9 273) were diagnosed with bothersome tinnitus. In a multivariable logistic regression mod, the following factors were associated with onsetting of tinnitus: sleep disorder [Odds Ratio(OR)=3.74] and noise exposure(OR=1.99). The risk of disease was lowest in the age of 30-40 years old, while the risk of disease was higher for people under 30 and over 40. In another multivariable logistic regression mode, the following factors were associated with having bothersome tinnitus: older people were more likely to suffer from tinnitus, sleep disorders (OR=4.68) and noise exposure (OR=1.56). Conclusions: The prevalence of tinnitus in Sichuan and Chongqing is about 34.83%, but most of the tinnitus is short-lived and has low loudness, which will not affect the patients. Only a small number of patients with tinnitus (3.99%) persist and affect their health and need treatment. The occurrence and exacerbation of tinnitus may be related to sleep, age, and noise exposure.

Intrinsic Spin Susceptibility and Pseudogaplike Behavior in Infinite-Layer LaNiO_{2}

The recent discovery of superconductivity in doped infinite-layer nickelates has stimulated intensive interest, especially for similarities and differences compared to that in cuprate superconductors. In contrast to cuprates, although earlier magnetization measurement reveals a Curie-Weiss-like behavior in undoped infinite-layer nickelates, there is no magnetic ordering observed by elastic neutron scattering down to liquid helium temperature. Until now, the nature of the magnetic ground state in undoped infinite-layer nickelates was still elusive. Here, we perform a nuclear magnetic resonance (NMR) experiment through ^{139}La nuclei to study the intrinsic spin susceptibility of infinite-layer LaNiO_{2}. First, the signature for magnetic ordering or freezing is absent in the ^{139}La NMR spectrum down to 0.24 K, which unambiguously confirms a paramagnetic ground state in LaNiO_{2}. Second, a pseudogaplike behavior instead of Curie-Weiss-like behavior is observed in both the temperature-dependent Knight shift and nuclear spin-lattice relaxation rate (1/T_{1}), which is widely observed in both underdoped cuprates and iron-based superconductors. Furthermore, the scaling behavior between the Knight shift and 1/T_{1}T has also been discussed. Finally, the present results imply a considerable exchange interaction in infinite-layer nickelates, which sets a strong constraint for the proposed theoretical models.

[Mutation analysis and prenatal diagnosis of MYO7A gene in a case of Usher syndrome type 1]

Objective: To analyze the clinical characteristics and identify the causative gene of a case with congenital deafness. Methods: Detailed medical history and clinical examination of a 4-year-old male child with congenital deafness were conducted in the First Affiliated Hospital of Army Military Medical University in June 2016. He was diagnosed with sensorineural deafness. The venous blood of the child and his parents was drawn, and genomic DNA was extracted. Proband's DNA was performed with targeted capture of high-throughput sequencing, then Sanger sequencing was used to verify the suspected mutation and segregation in this pedigree. According to the genetic diagnosis of the proband's deafness, ophthalmic examinations were performed. Genetic prenatal diagnosis was performed when the proband's mother was pregnant again. Results: The patient was detected with p.Trp1466Ter/p.Tyr2042Ter compound heterozygous mutations of MYO7A gene with targeted high-throughput sequencing. The mutation of p.Trp1466Ter was a reported mutation, while p.Tyr2042Ter has not been reported. In addition to congenital deafness, retinitis pigmentosa was also found by ophthalmologic examination, and the patient was clinically diagnosed with Usher syndrome type 1. Amniocentesis and fetal DNA sequencing were performed on the repregnancy fetus of this family at 18 weeks of gestation. The heterozygous mutation of MYO7A gene p.Tyr2042Ter was found, and the other allele was the wild type, indicating that the child will not exhibit clinical manifestations of Usher syndrome type 1. Indeed, the second child passed neonatal hearing screening. Conclusions: The clinical features and genetic variants were delineated in this family with Usher syndrome type 1. The results of the current study have enriched the phenotype and genotype data of the disease and provided a basis for genetic counseling.

[Clinical analysis of eosinophilic gastroenteritis in 71 children]

Objective: To summarize the clinical data including manifestations, diagnosis, treatment and prognosis of eosinophilic gastroenteritis (EGE) in children. Methods: A retrospective analysis was performed in 71 patients with pathologically proven EGE at Beijing Children's Hospital Affiliated to Capital Medical University from January 2008 to January 2017. Their clinical manifestations, laboratory and imaging examinations, endoscopic findings, histopathological examinations, and treatment were collected and analyzed. Results: Among 71 EGE cases, 47 (66%) cases were male and 24 (34%) cases were female, and the median age was 9.2 (0.2-16.5) years old. The main clinical manifestations included abdominal pain (76%, 54/71), vomiting (68%, 48/71), anorexia (54%, 38/71), weight loss (38%, 27/71), and diarrhea (37%, 26/71). There were 27 cases (38%) with a history of allergic diseases or family history. The median absolute value of eosinophil in peripheral blood of the 71 patients was 0.4 (0-36.8)×10(9)/L, and 27 cases (38%) showed an increase in eosinophil counts. Serum IgE was measured in 52 patients (104.3 (3.4- 3 000.0)×10(3) U/L), and 30 patients (58%) showed an increase in serum IgE. A large number of eosinophils ((41.0±8.5)/HP) were found in 3 patients' ascites. The endoscopic examination of upper gastrointestinal tract revealed hyperemic edema in 62 cases (87%), plaque in 44 cases (62%), erosion in 17 cases (24%) and ulceration in 16 cases (23%). Histopathologically, in 8 cases (11%) the disease involved both stomach and duodeneum, in 21 cases (30%) involved stomach only, and in 37 cases (52%) involved duodeneum only. In addition, in 6 cases (8%) the disease involved esophagus and in 10 cases (14%) involved colorectum. Microscopically, eosinophil counts averaged 67/HP, 33/HP, 40/HP and 38/HP in esophageal, gastric, duodenal and colorectal mucosa respectively. A total of 34 cases were treated with glucocorticoid, and all these patients had alleviation of symptoms, which occurred within 14.9 days on average, but EGE recurred in 11 cases (32%). Conclusions: The clinical symptoms and endoscopic findings of EGE are diverse and nonspecific. Histopathological examination of gastrointestinal mucosa is particularly important for the diagnosis. Glucocorticoid treatment is effective, but the patients with EGE are prone to relapse.

[Clinical analysis of intestinal lymphangiectasia in 47 children]

Objective: To analyze the clinical manifestations, diagnosis, treatment and prognosis of intestinal lymphangiectasia (IL) in children in order to improve the skills of diagnosis and treatment of IL. Method: Clinical manifestations, laboratory findings, gastroscopic findings, histopathological examinations and lymphatic radionuclide imaging assessments were analyzed retrospectively among 47 IL patients who were hospitalized in the Gastroenterology Department of Beijing Children's Hospital Affiliated to Capital Medical University from June 2007 to December 2015. All patients were followed up by telephone. According to the various causes, the patients were divided into the primary intestinal lymphangiectasia (PIL) group and secondary IL group, and their clinical manifestations were compared by t test, Rank sum test or Chi-square test. Result: In 47 IL patients, there were 38 children (81%) younger than 3 years old. There were 43 PIL patients (91%) and 4 secondary IL patients (9%). Between PIL and secondary IL, there were statistical differences in serum albumin (t=-3.950, P<0.005) , globulin(t=-2.850, P=0.007), age of onset(U=27.000, P=0.024), age at diagnosis(U=29.000, P=0.030) and course of disease(U=26.500, P=0.023), whereas there were no statistical differences in lymphocyte count, IgG, lymphatic radionuclide imaging, histopathology and gender(all P>0.05). Edema (44 cases, 94%), diarrhea (42 cases, 89%), accompanied with infection (35 cases, 74%) and ascites (30 cases, 64%) were the main clinical manifestations. In 47 IL patients, 45 patients were done gastroscopy and histopathological examinations, and there were 31 patients' histopathological examinations(69%) were positive. Forty patients were done lymphatic radionuclide imaging, and there was evidence of protein losing from gut via lymphatic radionuclide imaging in 39 patients(98%). Among 47 patients, 35 patients (74%) were followed up, 32 patients had good prognosis, 2 patient failed to show evidence of improvement, 1 patient died and no patient experienced a relapse till the end of the follow-up. In 35 patients, 28 patients were treated with medium chain triglycerides (MCT) dietary therapy, 26 patients showed improvement in symptoms, and 2 patients had no improvement. Among 35 patients with follow-up, there were 6 patients received surgical treatment, and their symptoms were improved. Conclusion: PIL are the majority of IL in children younger than 3 years old. The main clinical manifestations are edema, diarrhea, accompanied with infection and ascites. For the patients without the evidence of lymphangiectasia from duodenum histopathological examination, further consideration of lymphatic radionuclide imaging, clinical manifestations, and laboratory studies are needed to make a final diagnosis. MCT dietary therapy is the cornerstone of IL medical management.

[Clinical analysis of 11 children with pancreatic cystic fibrosis]

Objective: To increase the recognition of pancreatic cystic fibrosis (PCF) in children and facilitate diagnosing and treatment of this rare entity. Method: This is a retrospective analysis of children who presented to Beijing Children's Hospital affiliated to Capital Medical University from January 2010 to December 2015. We describe their clinical features, laboratory testing and management. Result: Eleven children were diagnosed with PCF by genetic testing or sweat chloride test during these 5 years, including 4 boys and 7 girls. Their age ranged from 0.5-14.3 (mean 9.0±3.9) years. Family history was positive in 3 children. Significant clinical findings on presentation were: malnutrition 6, including 2 cases of mild, moderate and severe malnutrition each; diarrhea 4 (yellow mushy or watery stool with frequency ranging from 2-5 times a day), including 1 case of acute diarrhea and 3 of chronic diarrhea, 3 of them had steatorrhea; abdominal pain 3. All of them had pancreatic lesions shown by abdominal ultrasound. Blood tests showed 6 cases had elevated serum amylase and lipase. The main treatment was pancreatic replacement therapy and nutritional support. Conclusion: PCF is rare in children. Malnutrition, diarrhea and abdominal pain are the main clinical manifestations. Treatment is mostly pancreatic enzymes replacement and supportive care.

Role of the C-terminal domain in inactivation of brain and cardiac sodium channels

Inactivation is a fundamental characteristic of Na(+) channels, and small changes cause skeletal muscle paralysis and myotonia, epilepsy, and cardiac arrhythmia. Brain Na(v)1.2a channels have faster inactivation than cardiac Na(v)1.5 channels, but minor differences in inactivation gate structure are not responsible. We constructed chimeras in which the C termini beyond the fourth homologous domains of Na(v)1.2a and Na(v)1.5 were exchanged. Replacing the C-terminal domain (CT) of Na(v)1.2a with that of Na(v)1.5 (Na(v)1.2/1.5CT) slowed inactivation at +40 mV approximately 2-fold, making it similar to Na(v)1.5. Conversely, replacing the CT of Na(v)1.5 with that of Na(v)1.2a (Nav1.5/1.2CT) accelerated inactivation, making it similar to Na(v)1.2a. Activation properties were unaffected. The voltage dependence of steady-state inactivation of Na(v)1.5 is 16 mV more negative than that of Na(v)1.2a. The steady-state inactivation curve of Na(v)1.2a was shifted +12 mV in Na(v)1.2/1.5CT, consistent with destabilization of the inactivated state. Conversely, Na(v)1.5/1.2CT was shifted -14 mV relative to Na(v)1.5, consistent with stabilization of the inactivated state. Although these effects of exchanging C termini were consistent with their effects on inactivation kinetics, they magnified the differences in the voltage dependence of inactivation between brain and cardiac channels rather than transferring them. Thus, other parts of these channels determine the basal difference in steady-state inactivation. Deletion of the distal half of either the Na(v)1.2 or Na(v)1.5 CTs accelerated open-state inactivation and negatively shifted steady-state inactivation. Thus, the C terminus has a strong influence on kinetics and voltage dependence of inactivation in brain Na(v)1.2 and cardiac Na(v)1.5 channels and is primarily responsible for their differing rates of channel inactivation.

Medical radiation usage and exposures from medical X ray diagnosis in Shandong province of China

Shandong province is situated in the eastern part of China with a population of 88 million. A collaborative survey was conducted in 1999 to investigate the medical radiation usage and the patients' exposures from medical X ray diagnosis in this province. There were three stages in this survey: general survey, sampling survey and dose survey. Patients' entrance surface doses (ESD) were measured using thermoluminescence dosemeters (TLDs) attached to the patient's skin. All the hospitals in this province and 2153 patients were included in this survey. The frequencies of tele- and brachytherapy were 1.450 and 1.685 per 1000 population in 1996 and 1998 respectively. The frequency of diagnostic nuclear medicine was 0.325 and 0.412 per 1000 population in 1996 and 1998 respectively; for therapeutic nuclear medicine, it was 0.015 and 0.021. The total annual frequencies of every type of X ray examination and interventional radiology (IVR) in 1996 and 1998 were 179.8 and 200.0 per 1000 population respectively. The main type of X ray examination was chest fluoroscopy, which made up about 39% of the total. The average entrance surface doses were comparatively high for the examinations of CT, gastrointestinal tract, lumbarspine, urography, angiography, hip and cerebral angiography.

Proline-rich motifs of the Na+/H+ exchanger 2 isoform. Binding of Src homology domain 3 and role in apical targeting in epithelia

The NHE2 isoform of the Na+/H+ exchanger (NHE) displays two proline-rich sequences in its C-terminal region that resemble SH3 (Src homology 3)-binding domains. We investigated whether these regions (743PPSVTPAP750, termed Pro-1, and 786VPPKPPP792, termed Pro-2) can bind to SH3 domains and whether they are essential for NHE2 function and targeting. A fusion protein containing the Pro-1 region showed promiscuous binding to SH3 domains of several proteins in vitro, whereas a Pro-2 fusion bound preferentially to domains derived from kinases. In contrast, cytoplasmic regions of NHE1, NHE3, or NHE4 failed to interact. When expressed in antiporter-deficient cells, truncated NHE2 lacking both Pro-rich regions catalyzed Na+/H+ exchange, retained sensitivity to intracellular ATP, and was activated by hyperosmolarity, resembling full-length NHE2. The role of the Pro-rich regions in subcellular targeting was examined by transfection of epitope-tagged forms of NHE2 in porcine renal epithelial LLC-PK1 cells. Both full-length and Pro-2-truncated NHE2 localized almost exclusively to the apical membrane. By contrast, a mutant devoid of both Pro-1 and Pro-2 was preferentially sorted to the basolateral surface but also accumulated intracellularly. These observations indicate that the region encompassing Pro-1 is essential for appropriate subcellular targeting of NHE2.

Identification of sites required for down-regulation of Na+/H+ exchanger NHE3 activity by cAMP-dependent protein kinase. phosphorylation-dependent and -independent mechanisms

We recently identified a region within the cytoplasmic C-terminal tail of the Na+/H+ exchanger NHE3 isoform (residues 579 to 684) which is essential for inhibition of transport activity by cAMP-dependent protein kinase (PKA) (Cabado, A. G., Yu, F. H., Kapus, A., Gergely, L., Grinstein, S., and Orlowski, J. (1996) J. Biol. Chem. 271, 3590-3599). To further define determinants of PKA regulation, six serine residues located in potential recognition sequences for PKA within, or adjacent to, this region (positions 552, 605, 634, 661, 690, and 691) were altered either independently or in various combinations using site-directed mutagenesis. Wild type and mutant NHE3s tagged with the influenza virus hemagglutinin epitope were stably expressed in exchanger-deficient Chinese hamster ovary cells (AP-1) for functional studies. Of the individual mutations examined, only substitutions at Ser605 or Ser634 affected sensitivity to forskolin, an activator of adenylate cyclase, although partial inhibition of NHE3 activity by forskolin remained. By contrast, simultaneous mutation of both these serines completely abolished cAMP-mediated inhibition of NHE3 without greatly affecting basal transport activity. Two-dimensional analysis of tryptic digests of immunoprecipitated NHE3 labeled in vivo with [32P]orthophosphate revealed several phosphopeptides under basal conditions. Phosphorylation was increased approximately 3-fold in one of these peptides following forskolin treatment, and this change was eliminated by mutation of residue Ser605. Thus, phosphorylation of Ser605 is essential for cAMP-mediated inhibition of NHE3. In addition, Ser634 is also required for the effect of cAMP, even though this residue does not become phosphorylated upon activation of PKA.

Distinct structural domains confer cAMP sensitivity and ATP dependence to the Na+/H+ exchanger NHE3 isoform

Agents known to increase cAMP levels in renal and intestinal epithelia decrease sodium absorption by inhibiting NHE3, an isoform of the Na+/H+ exchanger expressed at high levels in apical membranes of these cells. In contrast, the ubiquitous, housekeeping isoform of the exchanger (NHE1) is stimulated by cAMP in some cell types. Optimal activity of NHE3 as well as NHE1 requires the presence of ATP. To gain insight into the molecular mechanisms of ATP dependence and cAMP regulation of NHE3, a series of mutations were constructed by progressively truncating segments of the C-terminal cytoplasmic domain of the transporter at amino acid positions 684, 638, and 579 (named NHE3delta684, NHE3delta638, and NHE3delta579). In addition, chimeric antiporters were constructed with the N-terminal transmembrane domain of NHE3 linked to the entire cytoplasmic region of NHE1 (chimera NHE3/1) or vice versa (chimera NHE1/3). These constructs were heterologously expressed in antiport-deficient Chinese hamster ovary cells, and their activities were assessed by fluorimetric measurements of intracellular pH and by radioisotope determinations of Na+ influx. Forskolin, which directly stimulates adenylate cyclase, inhibited NHE3 as well as NHE1/3, but not NHE3/1, suggesting that the cytoplasmic domain of NHE3 was sufficient to confer sensitivity to inhibition by cAMP. Forskolin also inhibited the truncated mutant NHE3delta684 to an extent similar to that for wild type NHE3. However, the inhibitory effect was greatly reduced in NHE3delta638 and more profound truncations (NHE3delta579 obliterated the effect of forskolin. These findings suggest that a region found between amino acids 579 and 684 is essential for the cAMP response of NHE3. In contrast, comparable ATP dependence was observed in all exchanger constructs examined. These observations indicate that ATP dependence is conferred by a region of the molecule in or adjacent to the transmembrane domain, which is most conserved between isoforms. It is concluded that different sites, and therefore different mechanisms, underlie inhibition of NHE3 by cAMP and by depletion of ATP.

Plasma membrane Na+/H+ exchanger isoforms (NHE-1, -2, and -3) are differentially responsive to second messenger agonists of the protein kinase A and C pathways

Na+/H+ exchanger (NHE) activity is regulated by several types of receptors directly coupled to distinct classes (i.e. Gs, Gi, Gq, and G12) of heterotrimeric (alpha beta gamma) GTP-binding proteins (G proteins), which, upon activation, modulate production of various second messengers (e.g. cAMP, cGMP, diacylglycerol, inositol trisphosphate, and Ca2+). Recently, four isoforms of the rat Na+/H+ exchanger were identified by molecular cloning. To examine their intrinsic responsiveness to G protein and second messenger stimulation, three of these isoforms, NHE-1, -2, and -3, were stably expressed in mutant Chinese hamster ovary cells devoid of endogenous NHE activity (AP-1 cells). Incubation of cells with either AIF4-, a general agonist of G proteins, or cholera toxin, a selective activator of G alpha s that stimulates adenylate cyclase, accelerated the rates of amiloride-inhibitable 22Na+ influx mediated by NHE-1 and -2, whereas they inhibited that by NHE-3. Similarly, short term treatment with phorbol 12-myristate 13-acetate, which mimics diacylglycerol activation of protein kinase C (PKC), or with agents (i.e. forskolin, 8-(4-chlorophenylthio)-cAMP, and isobutylmethylxanthine) that lead to activation of cAMP-dependent protein kinase (PKA) also stimulated transport by NHE-1 and NHE-2 but depressed that by NHE-3. The effects of phorbol 12-myristate 13-acetate were blocked by depleting cells of PKC or by inhibiting PKC using chelerythrine chloride, confirming a role for PKC in modulating NHE isoform activities. Likewise, the PKA antagonist, H-89, attenuated the effects of elevated cAMPi on NHE-1, -2, and -3, further demonstrating the regulation by PKA. Unlike cAMPi, elevation of cGMPi by treatment with dibutyryl-cGMP or 8-bromo-cGMP had no influence on NHE isoform activities, thereby excluding the possibility of a role for cGMP-dependent protein kinase in these cells. These data support the concept that the NHE isoforms are differentially responsive to agonists of the PKA and PKC pathways.

Responsiveness of mutants of NHE1 isoform of Na+/H+ antiport to osmotic stress

Hypertonic activation of NHE1, the ubiquitous Na+/H+ exchanger, plays a central role in cell volume regulation, yet little is known about the underlying mechanism. We probed the osmotic responsiveness of full-length and truncated constructs of NHE1 transfected into cells lacking endogenous antiport activity. The hypertonic stimulation of NHE1 was preserved after heterologous transfection of the full-length NHE1 or of constructs truncated at positions 698 or 703. In contrast, mutants truncated at position 635 (delta 635) failed to respond to osmotic challenge. Transfectants (delta 635) behaved as if constitutively activated, having a permanently elevated cytosolic pH (pHi) under isotonic, unstimulated conditions. The delta 635 mutant displayed H+ binding with high affinity and low cooperativity. Constructs delta 582 or delta 566 had a reduced H+ sensitivity and were therefore inactive at resting pHi. Such cells were unresponsive to osmotic stress near physiological pHi but could be activated by shrinking after an acid load. Jointly, these results suggest that the H+ affinity and high cooperativity of the antiporter, earlier attributed to a single "modifier site," can be varied independently and are probably controlled by different regions of the molecule. The data indicate that volume or osmolarity-sensitive site(s) exist between the NH2-terminus and residue 566. This putative volume-sensitive site is therefore different from the site(s) postulated to mediate the stimulatory effects of calcium and growth factors.

Functional properties of the rat Na/H exchanger NHE-2 isoform expressed in Na/H exchanger-deficient Chinese hamster ovary cells

The primary structure and functional expression of the rat Na/H exchanger (NHE) NHE-2 isoform has recently been reported (Wang, Z., Orlowski, J., and Shull, G. E. (1993) J. Biol. Chem. 268, 11925-11928). To further characterize some of its functional properties, biochemical and pharmacological analyses were performed on exchanger-deficient Chinese hamster ovary cells (AP-1) that had been stably transfected with a full-length NHE-2 cDNA. Transport activity for NHE-2 was assayed by measuring amiloride-inhibitable 22Na+ influx following an acute intracellular acid load. Pharmacological analyses revealed that NHE-2 had a relatively high affinity for amiloride and some of its analogues. The most potent analogue was 5-(N-ethyl-N-isopropyl)amiloride (EIPA) (K0.5 = 79 nM), followed by 5-(N,N-dimethyl)amiloride (DMA) (K0.5 = 250 nM), amiloride (K0.5 = 1.4 microM), and benzamil (K0.5 = 320 microM). Nonamiloride compounds known to inhibit the activity of other Na/H exchanger isoforms also inhibited NHE-2 with the following order of potency: clonidine (K0.5 = 42 microM) > harmaline (K0.5 = 330 microM) approximately cimetidine (K0.5 = 330 microM). Biochemical analyses showed that the extracellular Na+ dependence of NHE-2 followed simple, saturating Michaelis-Menten kinetics with an apparent affinity constant for Na+ (KNa) of 50 mM. In contrast, intracellular H+ appeared to activate NHE-2 by a positive cooperative mechanism with an apparent half-maximal activation value of pK 6.90. Other cations, such as extracellular Li+ and H+, acted as competitive inhibitors of 22Na+ influx by NHE-2, with apparent Ki values of 3.0 mM and 10 nM, respectively. In contrast, extracellular K+ had no effect on the transport activity of NHE-2. These results indicated that the rat NHE-2 cDNA encodes a functional Na/H exchanger isoform with distinct properties compared to rat NHE-1 and -3.

A comparative study of the elbow joints in five species of Chinese macaques

In this paper, we report the findings of a comparative study of the elbow joints of five species of macaque that inhabit China: Macaca assamensis, M. arctoides, M. mulatta, M. thibetana and M. nemestrina. Results of multivariate analyses of size-related variables and indices of the elbow joint suggested that the breadths of the ventral aspect of the trochlea and of the medial epicondyle of the humerus as well as indices describing the head of the radius are important factors for discriminating these species. The elbow joint of M. arctoides was most similar to that of M. thibetana, no doubt reflecting recency of common ancestry and similarity in terrestrial locomotion. The structures of the elbow joints in M. nemestrina and M. assamensis seemed more adapted to arboreal quadrupedalism. The elbow joint of M. mulatta, however, appears intermediate between the most terrestrial and the most arboreal forms.

Effects of hydroxyflutamide on rats treated with a superovulatory dose of pregnant mare serum gonadotropin

Immature female rats treated with superovulatory doses of pregnant mare serum gonadotropin (PMSG) were used to study the effects of the antiandrogen hydroxyflutamide on steroid production, particularly the biologically active androgens, in two experiments. In the first experiment, animals were given either 5 mg hydroxyflutamide or vehicle alone at 30 and 36 h following 40 IU PMSG. Compared with the vehicle group, hydroxyflutamide treatment significantly reduced the percentage of degenerate oocytes recovered from oviducts (p less than 0.05). Serum levels of testosterone and androstenedione, and their aromatized product 17 beta-estradiol, significantly decreased (p less than 0.05) in the hydroxyflutamide-treated group; however, nonaromatizable androgen, 5 alpha-dihydrotestosterone, was not affected. In the second experiment, ovaries obtained 48 h after stimulation with 4 or 40 IU PMSG were incubated with and without hydroxyflutamide (10(-5) M) and (or) testosterone (10(-7) M) to study [4-14C]pregnenolone metabolism to major steroids. In 40 IU stimulated ovaries, hydroxyflutamide significantly decreased the metabolism of pregnenolone to progesterone (p less than 0.01) and androstenedione (p less than 0.01), while the production of 17 beta-estradiol increased significantly (p less than 0.05); however, pregnenolone conversions to testosterone and 5 alpha-dihydrotestosterone were not affected. Testosterone completely reversed the hydroxyflutamide-induced alteration of pregnenolone metabolism. In contrast, there was no difference in the pregnenolone conversion patterns between untreated and hydroxyflutamide or hydroxyflutamide plus testosterone groups in 4 IU stimulated ovaries. Present results confirm our previous finding that hydroxyflutamide decreases the percentage of abnormal oocytes recovered from superovulating rats and indicates that this hydroxyflutamide effect may be partly mediated by altered ovarian steroidogenesis following inhibition of androgen binding in the ovary.

Effects of a superovulatory dose of pregnant mare serum gonadotropin on follicular steroid contents and oocyte maturation in rats

Our previous study has shown that superovulatory treatment with pregnant mare serum gonadotropin (PMSG) in rats caused marked alterations in ovarian and serum steroid responses and coincidental increase in degenerate oocytes (Yun et al., 1987). This study examined the effects of superovulatory treatment (20 IU PMSG) on follicular steroid contents and oocyte maturation. Immature female rats aged 28-30 days were injected with 4 or 20 IU PMSG and sacrificed at 24, 48, 60, and 72 hr. Compared to control regimen, follicular content of progesterone (P) in superovulated rats significantly (P less than .05) increased at 48 hr. Androgen (A) content significantly (P less than .01) decreased below control level at 24 hr but significantly (P less than .05) increased above control level at 48 hr and 60 hr. There was no significant change in 17 beta-estradiol (E) content between the two groups. In control regimen, the ratio of A/E sharply decreased and the ratios of P/E and P/A increased steadily from 24 hr. However, superovulatory regimen showed a consistently steady state in the overall ratios of follicular steroids after 24 hr. Nuclear maturation of the majority of control oocytes recovered from oviducts at 72 hr was synchronized at metaphase II, whereas superovulated oocytes displayed different stages varying from prophase I to metaphase II at 24, 48, and 72 hr. The results provide direct evidence of atypical ovulations in superovulated oocytes with premature or asynchronous nuclear maturation and demonstrate a close relationship between meiotically aberrant oocytes and abnormal follicular steroidogenesis following superovulation with PMSG in rats.