Biomedical subjects

S K Hong

Publications and source records attributed to S K Hong.

At least 73 records · Page 4Linked to original sources

PubMed1998

Cell type-specific changes of the membrane properties of peripherally-axotomized dorsal root ganglion neurons in a rat model of neuropathic pain.

Recent evidence indicates that neuropathic pain from partial peripheral nerve injury is maintained by electrophysiologically abnormal signals from injured sensory neurons. To gain an insight into the mechanisms underlying this electrophysiological abnormality, we examined the effects of S1 spinal nerve transection on the membrane properties of S1 dorsal root ganglion neurons one to two weeks after injury. This injury produced significant action potential broadening [40% (1 ms) in C-, 149% (1.5 ms) in A delta- and 84% (0.5 ms) in A alpha/beta-cells], which was primarily due to the enhancement of the "shoulder" appearing on the falling phase of the action potential in C- and A delta-cells and the emergence of a shoulder in A alpha/beta-cells, and significant cell-type specific changes in the time-course of the rising phase of the action potential; i.e. an increase in rise time (A delta: 35%, 0.15 ms; A alpha/beta: 13%, 0.04 ms) and a decrease in the maximal rate of rise (A delta: 17%, 77 V/s; A alpha/beta: 13%, 79 V/s). In addition, the nerve injury led to a significant reduction of the rheobase, an index of neuronal excitability, in all types of cells (by 41% in C-, 71% in A delta- and 59% in A alpha/beta-cells). The reduction of rheobase in A-cells was associated with a concomitant increase in apparent input resistance (by 269% in A delta- and 192% in A alpha/beta-cells), which was measured near the resting membrane potential. By contrast, the rheobase reduction in C-cells was associated with a concurrent depolarizing shift (approximately 4 mV) of the resting membrane potential. The nerve injury-induced reduction of rheobase was not accompanied by related change in input resistance or threshold potential in any of the cell populations. The present results indicate that chronic peripheral axotomy of dorsal root ganglion neurons, which gives rise to neuropathic pain, produces profound changes in the action potential waveform of dorsal root ganglion neurons in a cell type-specific fashion. Furthermore, the results suggest that the axotomy increases the excitability of dorsal root ganglion neurons not by altering input resistance (i.e. leak conductance) or threshold potential, but by increasing apparent input resistance near the resting membrane potential in A-cells and decreasing the resting membrane potential in C-cells.

Action Potentials↗

PubMed1998

Characterization of two frizzled8 homologues expressed in the embryonic shield and prechordal plate of zebrafish embryos.

We have isolated and characterized two complete cDNA clones, Zfz8a and Zfz8b, which encode zebrafish Frizzled (Fz) homologues. The predicted protein sequences, spanning 579 and 576 amino acid residues for ZFz8a and ZFz8b, respectively, were highly homologous (78%) to each other and contained an extracellular cysteine-rich domain and seven transmembrane domains that are well conserved in Fz receptor protein members. In comparison with other Fz family members, ZFz8a and ZFz8b showed the highest homology with mouse Fz8 (MFz8), sharing 84 and 76% amino acid identity, respectively. The presence of Zfz8a and Zfz8b transcripts was detected by in situ hybridization in zebrafish embryos from the 512 cell stage, and their appearance in the future dorsal region could be observed before embryos reached the 30% epiboly stage. At shield stage, Zfz8a transcripts were expressed in both epiblast and shield whereas expression of Zfz8b was only detected in the embryonic shield. During gastrula stages, both Zfz8a and Zfz8b transcripts were found in anterior dorsal regions of the involuting mesendoderm (future prechordal plate). By the 2- to 3-somite stage, expression of both Zfz8a and Zfz8b was restricted to the prechordal plate and prospective anterior neurectoderm, although expression of the Zfz8a gene was no longer present in the most anterior portion of the prechordal plate, the polster. In one-eyed pinhead mutant embryos, which lack prechordal plate, both Zfz8a and Zfz8b transcripts were reduced, confirming the prechordal plate specificity of Zfz8a and Zfz8b gene expression. These results provide an additional evidence supporting the role of Wnt signaling in organizer-mediated axial patterning.

Amino Acid Sequence↗

PubMed1998

Biotransformation of 2-chloroaniline in the Fischer 344 rat: identification of urinary metabolites.

1. The biotransformation of a single i.p. dose of [14C]2-chloroaniline (1.0 mmol/kg, approximately 60 microCi/rat) was investigated in the urine and faeces of the male Fischer 344 rat. 2. During 24 h, 53.1% of the administered radioactivity was eliminated into the urine, while < 1% of the radioactivity appeared in the faeces. 3. The major biotransformation pathways were para-hydroxylation and sulphate conjugation. 4-Amino-3-chlorophenyl sulphate was the major urinary metabolite comprising 31.6% of total urinary radioactivity. The para-hydroxylated metabolite, 4-amino-3-chlorophenol (10.8%), and its O-glucuronide conjugate (3.7%) were also urinary metabolites. The formation of direct conjugates of 2-chloroaniline, the N-sulphate and N-glucuronide, was significant with as much as 18.6 and 8.6%, respectively, of these metabolites excreted in the urine. The parent compound, 2-chloroaniline, accounted for 16.9% of urinary radioactivity. 4. N-Acetylated products were minor metabolites present in urine as 2-chloro-4-hydroxyacetanilide and its sulphate or glucuronide conjugate. Neither 2-chloroacetanilide nor its oxidation products, 2-chloroglycolanilide and 2-chlorooxanilic acid, were urinary metabolites.

Acetylation↗

PubMed1998

Effects of FFA on insulin-stimulated glucose fluxes and muscle glycogen synthase activity in rats.

To examine effects of free fatty acids (FFA) on insulin-stimulated glucose fluxes, euglycemic hyperinsulinemic (86 pmol . kg-1 . min-1) clamps were performed for 5 h in conscious rats with (n = 8) or without (n = 8) lipid-heparin infusion. Glucose infusion rate required to maintain euglycemia was not different between the two groups during the first 2 h of clamps but became significantly lower with lipid-heparin infusion in the 3rd h and thereafter. To investigate changes in intracellular glucose metabolism during lipid-heparin infusion, additional clamps (n = 8 each) were performed for 1, 2, 3, or 5 h with an infusion of [3-3H]glucose. Insulin-stimulated whole body glucose utilization (Rd), glycolysis, and glycogen synthesis were estimated on the basis of tracer concentrations in plasma during the final 40 min of each clamp. Similar to changes in glucose infusion rate, Rd was not different between the two groups in the 1st and 2nd h but was significantly lower with lipid-heparin infusion in the 3rd h and thereafter. Whole body glycolysis was significantly lower with lipid-heparin infusion in all time periods, i.e., 1st, 2nd, 3rd, and 5th h of clamps. In contrast, whole body glycogen synthesis was higher with lipid-heparin infusion in the 1st and 2nd h but lower in the 5th h. Similarly, accumulation of [3H]glycogen radioactivity in muscle glycogen was significantly higher with lipid-heparin during the 1st and 2nd h but lower during the 3rd and 5th h. Glucose 6-phosphate (G-6-P) concentrations in gastrocnemius muscles were significantly higher with lipid-heparin infusion throughout the clamps. Muscle glycogen synthase (GS) activity was not altered with lipid-heparin infusion at 1, 2, and 3 h but was significantly lower at 5 h. Thus increased availability of FFA significantly reduced whole body glycolysis, but compensatory increase in skeletal muscle glycogen synthesis in association with accumulation of G-6-P masked this effect, and Rd was not affected in the early phase (within 2 h) of lipid-heparin infusion. Rd was reduced in the later phase (>2 h) of lipid-heparin infusion, when glycogen synthesis was reduced in association with reduced skeletal muscle GS activity.

Analysis of Variance↗

PubMed1998

Primary ovarian failure caused by a solvent containing 2-bromopropane.

Sixteen Korean female laborers who had been exposed to a cleaning solvent composed mainly of 2-bromopropane developed primary ovarian failure. Histologic findings from these patients' ovaries were similar to those observed in ovarian failure caused by radiation or chemotherapy, i.e., reduced number and developmental arrest of primary follicles, interstitial fibrosis and hyalinization of blood vessels. We followed their clinical course for 2 years and found that two patients recovered normal ovarian function spontaneously: one became pregnant and delivered a normal full-term baby, and the other resumed regular menstrual periods with normal hormonal values. Our observations support the idea that the increasing prevalence of ovarian failure in recent years might be due to an increase in presently unidentified environmental toxic agents.

Adult↗

PubMed1998

Development and progression of diabetic retinopathy in Koreans with NIDDM.

OBJECTIVE: To determine the incidence and risk factors for the development and progression of diabetic retinopathy in Korean patients with NIDDM. RESEARCH DESIGN AND METHODS: A total of 186 patients with NIDDM who did not have proliferative diabetic retinopathy (PDR) at baseline were prospectively studied for 5.3 +/- 1.0 years in an outpatient clinic of a university hospital. The incidence and progression of diabetic retinopathy was determined by annual funduscopic examination by an ophthalmologist. RESULTS: Of the 130 patients who were free of diabetic retinopathy at baseline, 30 developed it, giving an incidence of 44.4/1,000 person-years. Age and known duration of diabetes, mean fasting plasma glucose, and HbA1 levels during the follow-up period were higher in the patients who developed diabetic retinopathy. Of the 56 patients who had nonproliferative diabetic retinopathy at baseline, 11 developed PDR, giving an incidence of 37.5/1,000 person-years. The patients who progressed to PDR during follow-up (progressors) had a higher change of BMI and urinary albumin excretion rate at baseline and a higher mean HbA1 during the follow-up period than the nonprogressors. Cox proportional hazards analysis revealed that mean HbA1 was the only independent risk factor for both the development and progression of diabetic retinopathy. CONCLUSIONS: The incidence of PDR in Korean NIDDM patients is comparable to that reported in other populations. Poor glycemic control is the most important risk factor for both the development and progression of diabetic retinopathy in NIDDM patients.

Blood Glucose↗

PubMed1998

High serum lipoprotein(a) levels in Korean type 2 diabetic patients with proliferative diabetic retinopathy.

OBJECTIVE: To examine the possible association between serum lipoprotein(a) [Lp(a)] concentration and proliferative diabetic retinopathy (PDR) in Korean patients with type 2 diabetes. RESEARCH DESIGN AND METHODS: A total of 412 Korean outpatients with type 2 diabetes were examined. Diabetic retinopathy was determined by an ophthalmologist using fundoscopic examination. Serum Lp(a) levels were measured by two-site sandwich enzyme-linked immunosorbent assay. RESULTS: The patients with PDR had higher serum Lp(a) levels than those with no diabetic retinopathy or with nonproliferative diabetic retinopathy (NPDR). Multiple logistic regression analysis showed that high serum Lp(a) levels and the presence of diabetic nephropathy were independent variables having a statistically significant association with PDR. CONCLUSIONS: Korean type 2 diabetic patients with PDR had higher serum Lp(a) levels versus those with no diabetic retinopathy or with NPDR. Although these results suggest that Lp(a) might play a role in the occlusion of retinal capillaries leading to PDR, further prospective studies are required to prove the causal relationship.

Blood Glucose↗

PubMed1998

Incidence and determinants of microalbuminuria in Koreans with type 2 diabetes.

OBJECTIVE: The incidence of diabetic nephropathy in type 2 diabetes differs widely by race. Although clinical proteinuria is reportedly more common in East Asian type 2 diabetic patients than in their Caucasian counterparts, data on the incidence of microalbuminuria are not available. This study was undertaken to investigate the incidence and the determinants of microalbuminuria in Korean type 2 diabetic patients. RESEARCH DESIGN AND METHODS: A cohort of 188 Korean type 2 diabetic patients with initial normoalbuminuria were followed prospectively for 5.5 +/- 0.9 years in an outpatient clinic of a university hospital. The incidence of elevated urinary albumin excretion (UAE) (> 20 micrograms/min) and its relationship with baseline characteristics and follow-up data were determined. RESULTS: Of the 146 patients who finished the study, 37 showed persistently elevated UAE during follow-up, giving an incidence of 52/1,000 person-years. Age, duration of diabetes, and baseline UAE were significantly higher in the progressors than in the nonprogressors. More patients in the progressor group had retinopathy at baseline and at the end of follow-up. The mean values of fasting plasma glucose, HbA1, and systolic and diastolic blood pressure during the follow-up period were significantly higher in the progressors than in the nonprogressors. Cox proportional hazards analysis revealed that presence of retinopathy, duration of diabetes, mean fasting plasma glucose, and mean systolic blood pressure during follow-up are independent variables that have a statistically significant influence on the development of microalbuminuria. CONCLUSIONS: The incidence of microalbuminuria in Korean type 2 diabetic patients is lower than that reported in Pima Indians with type 2 diabetes but is as high as that in Caucasians with type 1 diabetes. Presence of diabetic retinopathy, poor glycemic control, and high blood pressure are risk factors for development of microalbuminuria in Koreans with type 2 diabetes.

Aged↗

PubMed1997

3,4-Dicholoroaniline acute toxicity in male Fischer 344 rats.

The aromatic amine, 3,4-dichloroaniline (DCA) is an important intermediate in the chemical production of agricultural chemicals. A previous study had shown that nephrotoxicity was apparent 48 h after injection of 3,4-DCA. The purpose of this study was to examine the potential for 3,4-DCA to be toxic to the kidney, liver and urinary bladder 24 h after acute administration. Male Fischer 344 (F344) rats were injected (intraperitoneal (i.p.)) with 0.4, 0.8 or 1.0 mmol/kg 3,4-DCA hydrochloride (HCl) salt (2.5 ml/kg, 25% ethanol). Nephrotoxicity was apparent within 24 h in the 0.8 and 1.0 mmol/kg 3,4-DCA treated group and was characterized by elevated (P < 0.05) blood urea nitrogen (BUN) and kidney weight. Renal cortical slice accumulation ofp-aminohippurate (PAH) was also decreased in the 0.8 and 1.0 mmol/kg 3,4-DCA treated group relative to pair fed controls (PFC). Cellular changes were noted in the liver and bladder 24 h after 3,4-DCA administration. Plasma alanine transaminase (ALT) activity was elevated (P < 0.05) above PFC values 24 h after treatment with 0.8 or 1.0 mmol/kg indicating liver damage was apparent within 24 h. Morphological damage was apparent along the centrilobular region. Hematuria was observed in the 0.8 and 1.0 mmol/kg 3,4-DCA treated groups. Infiltration of erythrocytes and polymorphonuclear leukocytes was apparent within the urinary bladder upon examination by light microscopy. These results indicated that 3,4-DCA was toxic within 24 h and that the target tissues were the kidney, liver and urinary bladder. In vitro studies were conducted to compare the toxicity of two forms of 3,4-DCA, the free base and hydrochloride salt to determine whether chemical form contributes to renal cortical slice toxicity. Lactate dehydrogenase (LDH) release was elevated above control by 120 min exposure to 2 mM 3,4-DCA free base or hydrochloride salt. Pyruvate directed gluconeogenesis in renal slices was decreased relative to control by 0.5 mM 3,4-DCA free base and hydrochloride salt. The results from the in vitro studies indicates that the chemical form did not modify in vitro renal cortical slice toxicity.

Alanine Transaminase↗

PubMed1997

Effects of sodium sulfate on acute N-(3,5-dichlorophenyl)succinimide (NDPS) nephrotoxicity in the Fischer 344 rat.

The agricultural fungicide N-(3,5-dichlorophenyl)succinimide (NDPS) induces acute polyuric renal failure in rats. Results of previous studies have suggested that NDPS may induce nephrotoxicity via conjugates of NDPS metabolites. Thus, the purpose of this study was to examine if administered sodium sulfate could alter NDPS nephrotoxicity. Male Fischer 344 rats (four rats per group) were administered a single intraperitoneal (i.p.) injection of sodium sulfate (0.035, 0.07, 0.35 or 3.5 mmol/kg) or sodium chloride (7.0 mmol/kg) 20 min before NDPS (0.2, 0.4 or 0.8 mmol/kg) or NDPS vehicle (sesame oil, 2.5 ml/kg) and renal function monitored at 24 and 48 h. High dose sodium sulfate (3.5 mmol/kg) markedly attenuated NDPS nephrotoxicity, while sodium chloride had no effect on NDPS-induced renal effects. NDPS nephrotoxicity was also attenuated by a pretreatment dose of 0.35 mmol/kg sodium sulfate, while 0.07 mmol/kg sodium sulfate pretreatment potentiated NDPS 0.2 mmol/kg to produce nephrotoxicity without markedly attenuating NDPS 0.4 mmol/kg to induce renal effects. A dose of 0.035 mmol/kg sodium sulfate did not potentiate NDPS 0.2 mmol/kg to induce nephrotoxicity. These results suggest that sulfate conjugates of NDPS metabolites might contribute to NDPS nephrotoxicity.

Animals↗

PubMed1997

NMDA receptors are important for both mechanical and thermal allodynia from peripheral nerve injury in rats.

Previous studies showed that heat-hyperalgesia and mechanical allodynia produced by chronic constrictive injury of the sciatic nerve were differentially sensitive to the NMDA receptor antagonist dextrorphan and to morphine and other opioid receptor agonists. These results support the hypothesis that different kinds of neuropathic pain symptoms are caused by different pathological mechanisms. In the present study we determined whether mechanical and thermal allodynia produced by unilateral transection of the 'superior' caudal trunk which innervates the tail in rats were differentially sensitive to the non-competitive NMDA receptor antagonist MK-801. Injection of MK-801 (0.3 mg/kg, i.p.) prior to nerve injury delayed the emergence of both types of allodynia; the antagonist-treated rats exhibited neither mechanical nor thermal allodynia at least for 4 days after the injury, whereas untreated control rats exhibited clear signs of allodynia from the first day after the injury. MK-801 injection on post-injury day 14, when the allodynia was near peak severity, suppressed temporarily both the mechanical and thermal allodynia. These results suggest that the mechanical and thermal allodynia from partial denervation of the tail are both dependent on NMDA receptors in their induction and maintenance. Thus, our results do not support the notion that different pathological mechanisms underlie different modalities of neuropathic pain from partial peripheral nerve injury.

Animals↗

PubMed1997

Characterization of methemoglobin formation induced by 3,5-dichloroaniline, 4-amino-2,6-dichlorophenol and 3,5-dichlorophenylhydroxylamine.

3,5-Dichloroaniline is an intermediate in the production of certain fungicides. This study characterized the capacity of 3,5-dichloroaniline and two putative metabolites to induce methemoglobin formation. In vivo intraperitoneal (i.p.) administration of 0.8 mmol/kg 3,5-dichloroaniline resulted in elevated (P < 0.05) methemoglobin levels at 2 and 4 h after injection and returned to control values within 8 h. In vitro methemoglobin generation was monitored in washed erythrocytes incubated for 60 min at 37 degrees C with 4 and 8 mM 3,5-dichloroaniline. Methemoglobin generation in vitro was higher (P < 0.05) than control values in erythrocytes incubated for 30 min with 0.2-0.6 mM 4-amino-2,6-dichlorophenol or 5-100 microM 3,5-dichlorophenylhydroxylamine. The in vitro methemoglobin generating capacity in decreasing order was: 3,5-dichlorophenylhydroxylamine > 4-amino-2,6-dichlorophenol > > 3,5-dichloroaniline. The results of the in vitro studies further indicated that none of the compounds tested induced lipid peroxidation. Erythrocytes incubated with 5-100 microM 3,5-dichlorophenylhydroxylamine in vitro were associated with depletion of glutathione. These results indicated that: (a) 3,5-dichloroaniline and its metabolites can induce methemoglobin formation; (b) the N-hydroxy metabolite was the most potent inducer of hemoglobin oxidation and (c) glutathione depletion was associated with methemoglobin formation by 3,5-dichlorophenylhydroxylamine.

Aniline Compounds↗

PubMed1997

4-Amino-2,6-dichlorophenol nephrotoxicity in the Fischer 344 rat: protection by ascorbic acid, AT-125, and aminooxyacetic acid.

A halogenated derivative of 4-aminophenol, 4-amino-2, 6-dichlorophenol (ADCP), is a potent nephrotoxicant and a weak hepatotoxicant in Fischer 344 rats. Although the mechanism of ADCP nephrotoxicity is unknown, ADCP could undergo oxidation to a reactive intermediate, such as a 4-amino-2,6-dichlorophenoxy radical or 2,6-dichloro-1,4-benzoquinoneimine, which can generate additional free radicals and/or covalently bind to cellular proteins. The toxic process might also be mediated by glutathione (GSH) conjugates of ADCP, as suggested for the mechanism of 4-aminophenol nephrotoxicity. In this study, the effects of modulators of oxidation and GSH conjugation-related metabolism or transport on ADCP-induced nephrotoxicity were examined. In one set of experiments, male Fischer 344 rats (four/group) were intraperitoneally (ip) administered ADCP (0.38 mmol/kg) only or coadministered an antioxidant, ascorbic acid (1.14 mmol/kg, ip) with ADCP. Administration of ascorbic acid markedly reduced both functional nephrotoxicity and morphological changes induced by ADCP. Administration of a gamma-glutamyltransferase (GGT) inhibitor, l-(alphaS, 5S)-alpha-amino-3-chloro-4,5-dihydroxy-5-isoxazoleacetic acid (10 mg/kg, ip), or a cysteine conjugate beta-lyase inhibitor, aminooxyacetic acid (0.5 mmol/kg, ip), 1 hr before ADCP (0.38 mmol/kg) challenge partially protected rats against ADCP nephrotoxicity. In contrast, administration of an organic anion transport inhibitor, probenecid (140 mg/kg, ip), 30 min before ADCP had little effect on ADCP nephrotoxicity. The GSH depletor, buthionine sulfoximine (890 mg/kg, ip), was given 2 hr prior to ADCP and only minimal protection was noted. In addition, the nonprotein sulfhydryl (NPSH) contents in renal cortex and liver were determined at 2 hr following the administration of ADCP only or ascorbic acid/ADCP. Ascorbic acid afforded complete prevention of the depletion of NPSH in the kidney and liver caused by ADCP administration and also prevented the elevation of renal glutathione disulfide content induced by ADCP. The results indicate that oxidation of ADCP appears to be essential to ADCP nephrotoxicity and that GSH or GSH-derived conjugates of ADCP may be partly responsible for the nephrotoxic effects of ADCP via a GGT-mediated mechanism.

Aminooxyacetic Acid↗

PubMed1997

Past and current obesity in Koreans with non-insulin-dependent diabetes mellitus.

To determine the prevalence of past and current obesity among patients with non-insulin-dependent diabetes mellitus (NIDDM) and to define the clinical characteristics of non-obese NIDDM patients in South Korea, we studied a cross-section of 749 NIDDM patients and a group of age- and sex-matched control subjects. Current height, weight and waist-to-hip ratio (WHR), the history of weight changes and the family history of diabetes were recorded. Obesity was defined as body mass index (BMI) > 25 kg/m2. The maximum lifetime BMI of diabetic patients was significantly higher than that of control subjects (P < 0.001). Compared with control subjects, current BMI was higher in diabetic women (P < 0.001) but not in diabetic men. In contrast, WHR of both diabetic men and women were significantly higher than those of controls (P < 0.05). BMI and WHR correlated significantly with fasting C-peptide levels and log-triglyceride levels in NIDDM patients. As a whole, 72% of the South Korean NIDDM patients had a history of past obesity as assessed by their maximum weight, while only 38% of them were currently obese. Compared with obese patients, non-obese patients were characterized by lower fasting serum C-peptide levels (P < 0.001), a higher percentage of insulin treatment (P < 0.05), lower maximum BMI (P < 0.001) and more pronounced weight loss from the time at their maximum weight (P < 0.001). In summary, increased upper body adiposity and a history of past obesity were associated with NIDDM in South Korea. Although most South Korean NIDDM patients were previously obese, many of them were currently not obese. Lower maximum BMI, lower serum C-peptide levels and a higher percentage of insulin treatment in non-obese NIDDM patients suggest that the capacity to increase insulin secretion in response to increasing weight gain is rather limited in these patients.

Adipose Tissue↗

PubMed1997

Correlation between anthropometric measurements of the oropharyngeal area and severity of apnea in patients with snoring and obstructive sleep apnea.

The aim of this study was to investigate the relationship between severity of apnea and anthropometric oropharyngeal measurements in patients with snoring and obstructive sleep apnea. A total of 22 patients complaining of snoring and apneic spell during sleep were evaluated by polysomnographic and anthropometric measurements of the oropharyngeal area. The horizontal width of the uvula at the mid-point and the length of the uvula were measured using a T-shaped ruler. The distance between the anterior pillars, posterior pillars and retromolar raphes were also measured. The correlation between these anthropometric measurements and polysomnographic parameters including the respiratory disturbance index (RDI) and the lowest arterial O2 saturation level (lowest SaO2) of the patients were analyzed. Of the anthropometric measurements, the horizontal width of the uvula showed a significant correlation with RDI and lowest SaO2. The results of the present study indicate that patients with broader uvula may have severer sleep apnea and that anthropometric oropharyngeal measurements may give additional information to polysomnographic findings for selecting surgical candidates.

Adult↗

PubMed1997

Ruptured proximal anterior cerebral artery (A1) aneurysm located at an anomalous branching of the fronto-orbital artery--a case report.

Cerebral aneurysms are occasionally associated with anomalies of cerebral arteries, that should be recognized pre- and intra-operatively. Most of the previous reports on the anomalies of the anterior cerebral artery have been concerned with hypoplasia, fenestration, and infra-optic course of the A1, variant A1 perforators or Heubner's artery, multi-channeled anterior communicating artery, and azygos anterior cerebral artery. The author experienced a patient with a ruptured proximal anterior cerebral artery (A1) aneurysm located at an anomalous origin of the fronto-orbital artery from the A1. The fronto-orbital artery normally branches off the anterior cerebral artery just distal to the anterior communicating artery (proximal A2). An anomalous branching of the fronto-orbital artery off the A1 seems very rare. This anomalous artery could be mistaken for an unusually large medial lenticulostriate artery, aberrant frontopolar artery, or the third A2. The author reviewed the literature on anomalies of the A1 and the fronto-orbital artery.

Adult↗

PubMed1996

A rice homeobox gene, OSH1, is expressed before organ differentiation in a specific region during early embryogenesis.

Homeobox genes encode a large family of homeodomain proteins that play a key role in the pattern formation of animal embryos. By analogy, homeobox genes in plants are thought to mediate important processes in their embryogenesis, but there is very little evidence to support this notion. Here we described the temporal and spatial expression patterns of a rice homeobox gene, OSH1, during rice embryogenesis. In situ hybridization analysis revealed that in the wild-type embryo, OSH1 was first expressed at the globular stage, much earlier than organogenesis started, in a ventral region where shoot apical meristem and epiblast would later develop. This localized expression of OSH1 indicates that the cellular differentiation has already occurred at this stage. At later stages after organogenesis had initiated, OSH1 expression was observed in shoot apical meristem [except in the L1 (tunica) layer], epiblast, radicle, and their intervening tissues in descending strength of expression level with embryonic maturation. We also performed in situ hybridization analysis with a rice organless embryo mutant, orl1, that develops no embryonic organs. In the orl1 embryo, the expression pattern of OSH1 was the same as that in the wild-type embryo in spite of the lack of embryonic organs. This shows that OSH1 is not directly associated with organ differentiation, but may be related to a regulatory process before or independent of the organ determination. The results described here strongly suggest that, like animal homeobox genes, OSH1 plays an important role in regionalization of cell identity during early embryogenesis.

Cell Differentiation↗

PubMed1996

Sprouting of sympathetic nerve fibers into the dorsal root ganglion following peripheral nerve injury depends on the injury site.

Peripheral nerve injury often induces sympathetic nerve fiber sprouting in the dorsal root ganglion (DRG) and injured nerve. Presently, the underlying mechanism and functional significance of the sprouting are unknown. This study was performed to see whether the degree of the sprouting in the DRG was a function of the distance between the DRG and injury site. To this aim, we compared two groups of rats with respect to the sympathetic nerve fibers sprouting in the S1-3 DRG; one group was subjected to unilateral inferior and superior caudal trunk transections at the level between the S3 and S4 spinal nerves (S34 group) and the other group at the levels between the S1 and S2, between S2 and S3 and between S3 and S4 spinal nerves (S123 group). The transections in both groups equally eliminated the inputs from the tail to the S1-3 DRG, but the distance from the S1/S2 DRG to the injury site was different between the two groups. Immunohistochemical staining with tyrosine hydroxylase (TH) antibody of the S1-3 DRG removed from rats a week after the injury revealed that the degree of penetration of TH-positive fibers into the S1 and S2 DRG was much more extensive in the S123 group than in the S34 group, whereas that into the S3 DRG was not significantly different between the two groups. These results suggest that the extent of the sympathetic nerve fiber sprouting in the DRG following peripheral nerve injury is inversely related to the distance between the DRG and injury site.

Animals↗