Review Recent progress in identification and characterization of loci associated with sex-linked congenital cataract.

Congenital cataract is a common cause of blindness in children; however, its pathogenesis remains unclear. Genetic factors have been shown to play an important role in the pathogenesis of congenital cataract. The current genetic models of congenital cataract include autosomal dominant, autosomal recessive, and sex-linked inheritance. Sex-linked congenital cataract could be inherited through the X or Y chromosome. Congenital cataract is a symptom associated with several X-linked disorders, including Nance-Horan syndrome, Lowe syndrome, Conradi-Hünermann-Happle syndrome, oculo-facio-cardio-dental syndrome, and Alport syndrome. On the other hand, the mechanism and characteristics of Y-linked congenital cataract remains to be identified. Despite its rarity, sex-linked congenital cataract has been known to seriously affect the quality of life of patients. In this review, we present our current understanding of the genes and loci associated with sex-linked congenital cataract. This could help identify novel approaches for the prevention, early diagnosis, and comprehensive disease treatment.

Combined pressure-thermal inactivation effect on spores in lu-wei beef--a traditional Chinese meat product.

AIMS: This study investigated the inactivation effect and kinetics of Bacillus coagulans and Geobacillus stearothermophilus spores suspended in lu-wei beef by combining high pressure (500 and 600 MPa) and moderate heat (70 and 80 °C or 80 and 90 °C). METHODS AND RESULTS: During pressurization, the temperature of pressure-transmitting fluid was tested with a K-type thermocouple, and the number of surviving cells was determined by a plate count method. The pressure come-up time and corresponding inactivation of Bacillus coagulans and G. stearothermophilus spores were considered during the pressure-thermal treatment. For the two types of spores, the results showed a higher inactivation effect in phosphate buffer solution than that in lu-wei beef. Among the bacteria evaluated, G. stearothermophilus spores had a higher resistance than B. coagulans spores during the pressure-thermal processing. One linear model and two nonlinear models (i.e. the Weibull and log-logistic models) were fitted to the survivor data to obtain relevant kinetic parameters, and the performance of these models was compared. The results suggested that the survival curve of the spores could be accurately described utilizing the log-logistic model, which produced the best fit for all inactivation data. CONCLUSIONS: The compression heating characteristics of different pressure-transmitting fluids should be considered when using high pressure to sterilize spores, particularly while the pressure is increasing. Spores can be inactivated by combining high pressure and moderate heat. SIGNIFICANCE AND IMPACT OF THE STUDY: The study demonstrates the synergistic inactivation effect of moderate heat in combination with high pressure in real-life food. The use of mathematical models to predict the inactivation for spores could help the food industry further to develop optimum process conditions.

Hippocampal spine-associated Rap-specific GTPase-activating protein induces enhancement of learning and memory in postnatally hypoxia-exposed mice.

Spine-associated Rap-specific GTPase-activating protein (SPAR) is a postsynaptic protein that forms a complex with postsynaptic density (PSD)-95 and N-methyl-d-aspartate receptors (NMDARs), and morphologically regulates dendritic spines. Mild intermittent hypoxia (IH, 16.0% O(2), 4 h/day for 4 weeks) is known to markedly enhance spatial learning and memory in postnatal developing mice. Here, we report that this effect is correlated with persistent increases in SPAR expression as well as long-term potentiation (LTP) in the hippocampus of IH-exposed mice. Furthermore, an infusion of SPAR antisense oligonucleotides into the dorsal hippocampus disrupted elevation of SPAR expression, preventing enhanced hippocampal LTP in IH-exposed developing mice and also reducing LTP in normoxic mice, without altering basal synaptic transmission. In SPAR antisense-treated mice, acquisition of the Morris water maze spatial learning task was impaired, as was memory retention in probe trails following training. This study provides the first evidence that SPAR is functionally required for synaptic plasticity and contributes to the IH-induced enhancement of spatial learning and memory in postnatal developing mice.

Gestational hypoxia alone or combined with restraint sensitizes the hypothalamic-pituitary-adrenal axis and induces anxiety-like behavior in adult male rat offspring.

We have reported that hypoxia affects the hypothalamic-pituitary-adrenal (HPA) axis and behavior by driving the expression of central corticotropin-releasing hormone (CRH) and its receptors in adult mammals, and this effect is modulated by other factors. Here, we address whether or not intermittent hypoxia (IH) or restraint (R) or a combination of both (IH+R) during gestation would result in differential alteration of the HPA axis and behavior of the adult male offspring. Gravid rats were exposed to IH in a hypobaric chamber (10.8% O(2), altitude of 5 km), R, or both, daily for 4 h for 21 days. Control parameters were set at sea level (20.9% O(2)). All the stressors significantly and differentially increased CRH and corticotropin-releasing factor receptor type 1 (CRHR1) expression but decreased corticotropin-releasing factor receptor type 2 (CRHR2) in the paraventricular nucleus of the hypothalamus (PVN), enhanced CRHR1 mRNA and CRHR2 mRNA expression in the anterior pituitary, and increased plasma adrenocorticotropic hormone (ACTH) and corticosterone (CORT) levels and adrenal weight in adult male offspring aged 120 days. Furthermore, norepinephrine (NE) and dopamine (DA) levels significantly increased in the locus coeruleus (LC), while the percentage of entries into the open arms of the elevated-plus maze test (EPM) markedly declined. In all the above effects, the combination-induced effect was stronger than each stressor alone. Confocal imaging showed a rich colocalization of CRHR1 with CRH or urocortin I (Ucn I), and CRHR2 with CRH or urocortin III (Ucn III) in the PVN, and CRHR1 with CRH in the LC in EPM-tested groups. In conclusion, IH or R alone or both in combination during gestation sensitize the HPA axis and induce anxiety-like behavior of the adult male offspring, and the combined effects are significantly great than IH or R alone. The CRH-NE neural circuit between the PVN and LC through CRH receptor driving might partly be involved in the effects. The differential colocalization of CRH with CRHR1 might be the neural basis of these effects.

Corticotropin-releasing hormone receptor 1 coexists with endothelin-1 and modulates its mRNA expression and release in rat paraventricular nucleus during hypoxia.

To determine whether corticotropin-releasing hormone receptor 1 (CRHR1) coexists with endothelin-1 (ET-1) in rat paraventricular nucleus (PVN), ET-1 expression and its regulation by CRH and CRHR1 under hypoxia, rats were exposed to simulated continuous hypoxia at 5 km altitude (CH5km, equal to 10.8% O(2)) in a hypobaric chamber for 1, 2, 5, 10, 15 or 25 days. ET-1, CRH, and its mRNA were measured using radioimmunoassay (RIA), immunohistochemistry, and in situ hybridization. The coexistence of ET-1 and CRHR1 was identified by confocal immunofluorescence. The results showed that CH5km caused a significant decrease of ET-1 level in PVN at 5 days, but decreased CRH on days 1 and 2 while it increased on days 5 and 10. CH5km induced ET-1 mRNA upregulation and ET-1 decrease at 5 days, the effects were completely reversed by treatment with five-daily-injections of a CRHR1 antagonist (butyl-[2,5-dimethyl-7-(2,4,6-trimethylphenyl)-7H-pyrrolo[2,3-d] pyrimidin-4-yl]-ethylamine: CP-154,526). Also, this treatment significantly reversed the CH5km-induced increase in CRH and CRHmRNA in PVN at 5 days. Moreover we found that the changes in expression of ET-1 and CRHR1 induced by CH5km were co-localized in parvocellular PVN cells. In conclusion, CRHR1 coexists with ET-1 in parvocellular PVN, continuous hypoxia stimulates ET-1 and ET-1mRNA as well as CRH and CRHmRNA, and CRHR1 evidently modulates ET-1 release and ET-1mRNA activation caused by continuous hypoxia.

Corticotropin-releasing factor receptor type 1 and 2 mRNA expression in the rat anterior pituitary is modulated by intermittent hypoxia, cold and restraint.

We had previously demonstrated that continual-hypoxia stimulated corticotropin-releasing factor (CRF)mRNA in hypothalamus, and release of CRF, as well as enhancing plasma adrenocorticotropic-hormone and corticosterone of rats. The present study demonstrates using in situ autoradiography that CRF receptor 1 (CRFR1) and CRF receptor 2 (CRFR2) mRNA in the rat anterior pituitary is changed by intermittent hypoxia, cold, restraint, alone and in combination. Rats were exposed to intermittent hypoxia for 4 h/day during various periods in a hypobaric chamber. Hypoxia equivalent to an altitude of around 2 km (16.0% O2) or 5 km (10.8% O2) caused a biphasic change in both CRFR1 and R2 mRNA, there being an initial significant decline on day 1 and then an enhancement by day 2. The increase of both receptor subtypes mRNA was relatively well maintained up to 15 days in rats exposed to 2 km intermittently. CRFR2 mRNA in rats exposed to 5 km, after peaking at day 2 therefore declined and was not different to controls at 15 days. Five kilometer hypoxia markedly reduced body weight gain. The increased CRFR1 mRNA was also induced by restraint alone, hypoxia+restraint and hypoxia+cold but not by cold alone. The CRFR2 mRNA was significantly increased by all the stresses except for hypoxia+restraint. These results show that the acute response to intermittent hypoxia is a decrease in the CRF receptor mRNA whereas longer exposure to the three environmental stressors hypoxia, cold and restraint is needed to provoke an increase. This may have important consequences for adaptation to high altitude. The significant differences between the expression of CRFR1 mRNA and CRFR2 mRNA in response to the different stimuli might suggest that the two receptors in the pituitary play different roles in behavior.

[The radioimmunoassay of growth hormone and prolactin and its application].

AIM: To set up a highly specific and sensitive double antibody radioimmunoassay (RIA) for determining the contents of growth hormone (GH) and prolactin (PRL) in pituitary and plasma of rats; To study the effects of acute hypoxia on GH and PRL of rats. METHODS: We use chloramine-T technique iodinate antigen and choose the equilibration and saturated procedure of RIA to add the preparations. RESULTS: Exposed to 7 km-hypoxia for 0.5 h, pituitary GH content increased (P < 0.05) and conversely, plasma GH levels were suppressed (P < 0.05); while the PRL levels in both pituitary and plasma were suppressed (P < 0.01); and there was no significantly difference between 5 km hypoxia groups and control. CONCLUSION: We have successfully established the method of radiolabel and double antibody RIA with highly sensitivity; acute hypoxia (7 km) suppressed the secretion of GH and PRL in rats.

[The autonomic nervous system involved in regulation of immune function in rats during hypoxia].

AIM: To study of autonomic nervous system modulation of lymphocyte proliferation during hypoxia. METHODS: Rats were exposed to 5 km and 7 km altitude in a hypobaric chamber for 24 h or 48 h, the effect of autonomic nervous system on mitogen-induced spleen lymphocyte response to the acute hypoxia was investigated. RESULTS: When rats were exposed to 5 km altitude for 24 h, which inhibited spleen T lymphocyte proliferation induced by concanavalin (Con A), but the action was abolished through peripheral sympathetic-destroyed. When mouse were exposed anoxia environment at 0.07 MPa for 10 min, the norepinephrine and epinephrine in plasma were increased markedly. T cells of rats were in vitro incubated simultaneously with ACh showing a concentration dependent enhancement of T cell proliferation. The plasma levels of ACh were decreased after rats were exposed to 5 km for 24 h. CONCLUSION: Autonomic nervous system was involved in the regulation of immune function in rats during hypoxia.

[Effect of hypoxia on activity of hypothalamo-pituitary- adrenal-cortex axis in rat].

AIM AND METHODS: In this experiment we used the methods of simulated hypoxia in a low-pressure cabin and RIA to investigate the effect of hypoxia on secretion of corticotropin-releasing factor (CRF) from hypothalamus and corticosterone from adrenal-cortex. And compare the effects of hypoxia on secretion of CRF and corticosterone in rat exposed to hypoxia for different time. RESULTS: During acute hypoxia the secretion of CRF and level of plasma corticosterone rose significantly comparing with control. After 5 days of exposed to hypoxia the augment of secretion of CRF and level of plasma corticosterone decreased and to 15 days exposed to hypoxia the secretion of CRF and level of plasma corticosterone approached to control. CONCLUSION: Hypoxia (2 h, 24 h) significantly activated HPA axis. After 5 days exposed to hypoxia the activity of HPA axis attenuated and began to recovery. After 15 days exposed to chronic hypoxia the activity of HPA axis has recovered to control level.

Hypoxia influences enkephalin release in rats.

To investigate hypoxia effects on leucine-enkephalin (L-ENK) levels of median eminence (ME) of hypothalamus in rats, and the possible glucocorticoid involvement in modulation. Hypoxia was stimulated in a hypobaric chamber. L-ENK levels were measured by specific radioimmunoassay during acute, and a comparison of L-ENK alteration was taken for bilateral adrenalectomy (ADX) with or without a replacement of dexamethasone (DEX). Acute hypoxia 10.8% O2 for 30 min and 2 h markedly enhanced L-ENK levels of ME from 23.99+/-7.25 in control to 51.26+/-16.96 (P<0.01) and 53.29+/-26.10 ng/mg protein (p<0.01), and acute hypoxia at 8.2% O2 significantly increased L-ENK of ME to 36.76+/-15.25 (p<0.05) and 32.09+/-3.58 ng/mg protein (p<0.05). The increased L-ENK was returned to normoxic level when hypoxia (10.8% O2) exposure lasted for 24 h. After ADX, 10.8% O2 hypoxia induced a sharp decline of L-ENK in the ME, but this decline was completely reversed by treatment with DEX (500 microg/rat, i.p.). Acute hypoxia increases L-ENK level of hypothalamic ME in rats, which may present a reduced and/or inhibited release of L-ENK, acting through a fast negative feedback mechanism of acute hypoxia activated high circulating glucocorticoid level.

Hypoxia influences somatostatin release in rats.

The impact of hypoxia on somatostatin (SS) secretion from the median eminence (ME) of the hypothalamus and the possible glucocorticosteroid involvement in modulating secretion, were investigated in adult male rats exposed to hypoxia. SS levels were measured by specific radioimmunoassay during acute and prolonged hypoxia as well as after bilateral adrenalectomy (ADX) with or without a replacement with dexamethasone (DEX). The results were as follows: (a) acute hypoxia (5 km altitude, 10.8% O(2)) for 2 and 24 h markedly increased SS content in ME, but acute severe hypoxia (7 km, 8.2% O(2) for 24 h) markedly decreased SS level in ME. (b) Chronic hypoxia (10.8% O(2)) from 5 to 25 days exposure did not significantly affect SS content of ME. (c) ADX alone increased SS content of ME and this increase was further enhanced after 2 h exposure to hypoxia. (d) The increased SS in ME of ADX rats was blocked by replacement with DEX (500 microg/rat i.p.). The data presented suggest that acute hypoxia stress may increase or decrease SS content of ME in rats, depending on the severity and duration of the hypoxia and that the stimulatory action of hypoxia on SS content of ME be may in part mediated by the increased corticosterone levels during hypoxia.

The response of growth hormone and prolactin of rats to hypoxia.

Effects of acute and chronic hypoxia on growth hormone (GH) and prolactin (PRL) of male rats were studied in a simulated hypobaric chambers at altitudes of 5 km (10.8% O2) and 7 km (7.2% O2), respectively. Acute hypoxia caused decreased plasma GH and increased pituitary GH content; both pituitary and plasma PRL contents at 2 h were decreased and plasma PRL level increased at 24 h. Prolonged exposure of hypoxia (5 km) to 25 days, both pituitary and plasma GH were obviously lower than control and pituitary PRL levels were decreased but plasma PRL increased markedly. The data presented suggest that long-term of hypoxia (10.8% O2) significantly suppresses body growth of rats and inhibits GH release and/or biosynthesis, which may in part correlate with decreased body weight gain; high circulating PRL concentration may be of significance in physiological adaptation to chronic hypoxia.

Effects of angiotensin II on release of CRH and AVP from hypothalamus during acute hypoxia.

AIM: To investigate the effects of angiotensin II (Ang II) on corticotropin-releasing hormone (CRH) and argipressin (AVP) release from median eminence (ME) of hypothalamus during acute hypoxia in rats. METHODS: Simulated hypoxia was performed in a hypobaric chamber. CRH and AVP were determined by radioimmunoassay (RIA). Plasma corticosterone concentration was measured by fluorometry. RESULTS: Ang II did not influence CRH release induced by hypoxia [CRH in group pretreated with Ang II (16 +/- 8) ng/ME vs control (15 +/- 4) ng/ME, both exposed to hypoxia with simulated altitude 7 km (8.2% O2)]. Ang II enhanced AVP release, from (5.7 +/- 1.6) ng/ME in control decreasing to (2.6 +/- 1.2) ng/ME (P < 0.05), meanwhile plasma corticosterone concentration was also increased markedly, from (356 +/- 58) in control to (536 +/- 134) micrograms/L plasma (P < 0.05), which was partly abolished by administration of AVP antiserum. CONCLUSION: Ang II might stimulate hypothalamo-pituitary-adrenal axis (HPA) through activating AVP but not CRH release during acute hypoxia.

[The enhancing effects of arginine-vasopressin on antibody level and lymphocyte proliferation of rats].

The effects of arginine-vasopressin (AVP) on some immune parameters of rats were studied by using icv of AVP. The hemolysin to sheep red blood cell and IgG production were enhanced by icv of 100, 800 ng AVP. Both the actions were partly blocked by icv preinjection of the V1 receptor antagonist DPAVP. It was also found that the NE and corticosterone levels in the serum of rats were significantly reduced after icv of AVP. The above results suggest that AVP executes immunofunctions through V1 receptors in the paraventricular nucleus of the brain. Considering our previous results, the AVP enhanced immunofunction may be related to its inhibition of corticotropin releasing factor release or the excitatory activity of sympathetic nerves.

[Beta-endorphin involved in the regulation of humoral immune function of rats during acute hypoxia].

In order to investigate the role of beta-endorphin in the regulation of humoral immune function of rats during acute hypoxia, the effects of beta-endorphin on mitogen-induced spleen lymphocyte DNA synthesis and hemolysin formation as well as IgG production to chicken egg albumen were observed. It was found that after rats received icv injection of beta-endorphin (1 ng/rat), the T-lymphocyte DNA content, the hemolysin-forming capacity of SRBC-sensitized rats and the IgG level were reduced significantly compared with the control (icv normal saline). Similar suppressive effects on immune function could be found after rats were exposed to 7 km altitude in a hypobaric chamber for 48 h. Pretreatment with icv injection of naltrexone, the immunosuppressive effects of acute hypoxia were partially blocked. Icv administration of beta-endorphin produced an increase in splenic cathcholamines, similar to those of hypoxia treated group (7 km for 12 h). All the above findings suggest that beta-endorphin may modulate the immune response to hypoxia stress via opioid receptor and its inhibitory action may be mediated by activating sympathetic nervous system.

[Norepinephrine regulation of T-lymphocyte proliferation of rat during acute hypoxia].

Interaction between the immune and neuroendocrine systems has long been noted. In the present study, the role of norepinephrine (NE) in immunoregulation of rats during simulated hypoxia in hypobaric chamber was examined. It was found that 7 km for 24 h of hypoxia inhibited T-lymphocyte proliferation by 41%. 7 d and 20 d of hypoxia, simulating 5 km altitude, reduces T-lymphocyte proliferation respectively 34% and 60%. Intracerebroventricular (i.c.v.) injection of 5 x 10(-6) mol/L NE decreased T-lymphocyte proliferation by 29%. I.c.v. injection of phentolamine 25 micrograms/rat prior to 7 km for 10 h hypoxia attenuated the hypoxia-induced suppression of T-lymphocyte proliferation from 42% to 21%. In additon, 7 km 10 h hypoxia increased CRF levels in blood and catecholamines in hypothalamus. An increased circulation CRF level was also noted after NE injection (i.c.v.) of 5 x 10(-6) mol/L. Hypoxia corresponding 7 km altitude for 10 h stimulates spleen-lymphocytes incubated with CRF, but T-lymphocyte proliferation decreclsed with increasing CRF concentration. These findings suggest that hypoxia inhibits T-lymphocyte proliferation probably through an immune inhibition action by CRF-NE.

Energy expenditure and quantitative oxidation of nutrients in rats (Rattus norvegicus) kept in different thermal environments and given two levels of dietary fiber.

A study was performed to investigate the effect of environmental temperature (16 degrees C, 24 degrees C or 32 degrees C) and dietary fiber (DF) on energy expenditure and quantitative oxidation of nutrients in rats. Forty-eight male rats, initial body weight 90-105 g, were allocated to eight groups in two series. The rats kept at 24 degrees C was repeated in both series. Low and high fiber diets (56 vs. 257 g DF/kg dry matter) were studied in 6-week balance experiments. The rats in all groups were offered the same amount of air-dried food. Indirect calorimetry was used to measure the energy metabolism. The difference in heat production (HP) calculated by RQ and CN methods was < 2% and was not affected by environmental temperature and DF. The relation between fat and protein oxidation changed from 1.54 to 1.00 when the ambient temperature changed from 16 degrees C to 32 degrees C. The contribution of carbohydrate oxidation to total HP was lowest at 16 degrees C, whereas the fat and protein oxidation was highest at 16 degrees C. The oxidation of nutrients was not influenced by DF. The additional energy retained at the higher temperatures had a constant ratio between fat and protein, i.e., 70:30. At an energy retention of 65.8 kJ/kg0.75 d or less, body fat is mobilized and only protein deposited. Because of higher HP, rats living in the cold environment used more fat as substrate for HP than rats kept in warmer environments. The cold environment results in an increase in the amount of interscapular brown adipose tissue, but no significant difference was found between DF levels.

[Inhibition effect of hypoxia on humoral immunity of rats].

To study the effect of hypoxia on humoral immunity function of rat and Ochotona curzoniae (pika), the specific antibody production to novel antigen IgG and immunoresponse to sheep red blood cell (hemolysin forming) were measured. The results show that hypoxia at altitude of 5 km and 7 km for 10 d resulted respectively in 10.3% (P < 0.05) and 21.9% (P < 0.05) decrement in hemolysin formation in rats, as compared with the control group kept at 2.3 km. When the rats were secondarily immunized and kept at the same hypoxia for 10 d, the reduction in hemolysin formation was 4.2% (P < 0.05) and 4.6% (P < 0.05) for the two respective altitudes. These changes, however, were not found in pikas. When rats were immunized two days before hypoxia, 5 km hypoxia for 5 d and 8 d failed to suppress hemolysin formation. Intracerebroventricular (i.c.v.) injection of CRF (1.0 microgram/rat), decreased hemolysin formation and production of IgG by 8.6% (P < 0.05) and 14.0% (P < 0.05) respectively, but intraperitoneal (i.p.) injection of CRF (1.0 microgram/rat) had no effect. On the other hand, i.c.v. injection of CRF receptor antagonist (alpha-helical CRF (9-41), 50 micrograms/rat) prior to 7 km hypoxia caused a hypoxia-induced suppression of IgG production from 24.2% to 12.1% (P < 0.05). Adrenalectomy in rats lowered hemolysin formation by 6.6% (P < 0.05). The above results demonstrate that hypoxia suppresses humoral immunity function and alters initial antigen processing probably through an increase of CRF in the central nervous system.

Hypoxia effects on hypothalamic corticotropin-releasing hormone and anterior pituitary cAMP.

AIM: To study the effects of acute and chronic hypoxia on hypothalamus-anterior pituitary-adrenocortex axis. METHODS: Rats and pikas were exposed to different altitude and periods. Animals were injected with CRH, Arg and NE in the third ventricle of the brain of rats. RESULTS: Anterior pituitary cAMP and plasma corticosterone levels of rats obviously increased during 1 h of hypoxia. cAMP was increased from 2.23 +/- 0.13 of control group to 7.7 +/- 0.7 of 5 km and 13.4 +/- 1.9 nmol/g wet tissue of 8 km, respectively. i.c.v. CRH, Arg and NE all activated HPA axis. The effects of CRH were most potent. CRH 2 microL 0.75 nmol i.c.v increased anterior pituitary of cAMP from 3.5 +/- 0.4 of control to 22.4 +/- 2.2 nmol/kg wet tissue. Stimulating altitude of 5000 m resulted in a 16.9% decrease in corticosterone level (P < 0.05), 8000 m resulted in a 47.5% decrease (P < 0.01) after hypoxia for 25 d. Hypoxia did not activate HPA axis in pikas. CONCLUSION: 1) Hypoxia stress activates the secretion of corticotrophin (ACTH) via cAMP; 2) Adrenocotical function of rats decays during chronic hypoxia; 3) Arg and NE regulate the secretion of plasma corticosterone and synthesis of pituitary cAMP at the hypothalamus level; 4) Hypoxia tolerance of the pika was high.