The functional anatomy of the basal ganglia of birds

To study how the basal ganglia can control movement in birds, we have reinvestigated the connections of the pigeon dorsal pallidum. Our results indicate that avian basal ganglia appear to control movement through major projections to several premotor pretectal and tegmental centres which innervate the tectum, and through a minor projection to a possible motor thalamic centre which innervates the Wulst. For such control, separate striatopallidal output circuits appear to exist in birds that are remarkably similar to those described in mammals, suggesting that avian and mammalian basal ganglia may control movement through similar mechanisms, and that the morphological substrate for such control evolved earlier than previously thought.

Manganese sulfate-dependent glycosylation of endogenous glycoproteins in human skeletal muscle is catalyzed by a nonglucose 6-P-dependent glycogen synthase and not glycogenin

Glycogenin, a Mn2+-dependent, self-glucosylating protein, is considered to catalyze the initial glucosyl transfer steps in glycogen biogenesis. To study the physiologic significance of this enzyme, measurements of glycogenin mediated glucose transfer to endogenous trichloroacetic acid precipitable material (protein-bound glycogen, i.e., glycoproteins) in human skeletal muscle were attempted. Although glycogenin protein was detected in muscle extracts, activity was not, even after exercise that resulted in marked glycogen depletion. Instead, a MnSO4-dependent glucose transfer to glycoproteins, inhibited by glycogen and UDP-pyridoxal (which do not affect glycogenin), and unaffected by CDP (a potent inhibitor of glycogenin), was consistently detected. MnSO4-dependent activity increased in concert with glycogen synthase fractional activity after prolonged exercise, and the MnSO4-dependent enzyme stimulated glucosylation of glycoproteins with molecular masses lower than those glucosylated by glucose 6-P-dependent glycogen synthase. Addition of purified glucose 6-P-dependent glycogen synthase to the muscle extract did not affect MnSO4-dependent glucose transfer, whereas glycogen synthase antibody completely abolished MnSO4-dependent activity. It is concluded that: (1) MnSO4-dependent glucose transfer to glycoproteins is catalyzed by a nonglucose 6-P-dependent form of glycogen synthase; (2) MnSO4-dependent glycogen synthase has a greater affinity for low molecular mass glycoproteins and may thus play a more important role than glucose 6-P-dependent glycogen synthase in the initial stages of glycogen biogenesis; and (3) glycogenin is generally inactive in human muscle in vivo.

Adhesion energy of receptor-mediated interaction measured by elastic deformation

We investigated the role of receptor binding affinity in surface adhesion. A sensitive technique was developed to measure the surface energy of receptor-mediated adhesion. The experimental system involved a functionalized elastic agarose bead resting on a functionalized glass coverslip. Attractive intersurface forces pulled the two surfaces together, deforming the bead to produce an enlarged contact area. The Johnson-Kendall-Roberts (JKR) model was used to relate the surface energy of the interaction to the elasticity of the bead and the area of contact. The surface energies for different combinations of modified surfaces in solution were obtained from reflection interference contrast microscopy (RICM) measurements of the contact area formed by the bead and the coverslip. Studies with surfaces functionalized with ligand-receptor pairs showed that the relationship between surface energy and the association constant of the ligand binding has two regimes. At low binding affinity, surface energy increased linearly with the association constant, while surface energy increased logarithmically with the association constant in the high affinity regime.

Cellular localization of huntingtin in striatal and cortical neurons in rats: lack of correlation with neuronal vulnerability in Huntington's disease

Immunohistochemistry and single-cell RT-PCR were used to characterize the localization of huntingtin and/or its mRNA in the major types of striatal neurons and in corticostriatal projection neurons in rats. Single-label immunohistochemical studies revealed that striatum contains scattered large neurons rich in huntingtin and more numerous medium-sized neurons moderate in huntingtin. Double-label immunohistochemical studies showed that the large huntingtin-rich striatal neurons include nearly all cholinergic interneurons and some parvalbuminergic interneurons. Somatostatinergic striatal interneurons, which are medium in size, rarely contained huntingtin. Calbindin immunolabeling showed that the vast majority of the medium-sized striatal neurons that contain huntingtin are projection neurons, but only approximately 65% of calbindin-labeled projection neurons (localized to the matrix compartment of striatum) were labeled for huntingtin. Calbindin-containing projection neurons of the matrix compartment and calbindin-negative projection neurons of the striatal patch compartment contained huntingtin with comparable frequency. Single-cell RT-PCR confirmed that striatal cholinergic interneurons contain huntingtin, but only approximately 65% of projection neurons contained detectable huntingtin message. The finding that huntingtin is not consistently found in striatal projection neurons [which die in Huntington's disease (HD)] but is abundant in striatal cholinergic interneurons (which survive in Huntington's disease) suggests that the mutation in huntingtin that causes HD may not directly kill neurons. In contrast to the heterogeneous expression of huntingtin in the different striatal neuron types, we found all corticostriatal neurons to be rich in huntingtin protein and mRNA. One possibility raised by our findings is that the HD mutation may render corticostriatal neurons destructive rather than render striatal neurons vulnerable.

Abnormally decreased HbA1c can be assessed with erythrocyte creatine in patients with a shortened erythrocyte age

OBJECTIVE

To investigate whether erythrocyte creatine can serve as a corrective index for HbA1c in patients with a shortened mean age of erythrocytes.

RESEARCH DESIGN AND METHODS

HbA1c and creatine in density-fractionated erythrocytes from 18 normal subjects were measured. HbA1c and erythrocyte creatine in the whole blood of 43 patients with liver cirrhosis (LC), 14 patients with hemolytic anemia (HA), 38 other patients with high reticulocyte counts (HRC) (>2.2%), and 59 normal subjects were also measured. The patients in this study all had normal blood glucose levels. A correction formula derived from the linear regression equation for the correlation between HbA1c and erythrocyte creatine was used to correct the patients' HbA1c values.

RESULTS

Among density-fractionated erythrocytes, the young cells exhibited low HbA1c and high creatine values. With progressively increasing density, HbA1c gradually increased and creatine gradually decreased. In the whole blood samples, the HbA1c values were significantly lower (P < 0.001) in LC, HA, and HRC patients than in normal subjects. By contrast, the erythrocyte creatine values were significantly higher (P < 0.001) in LC, HA, and HRC patients than in normal subjects. A linear correlation between HbA1c (y) and erythrocyte creatine (x) was observed (y=-0.224x + 5.00; n=154; r=-0.70; P < 0.001). Based on the regression equation, a correction formula was obtained. Low HbA1c values (<4.3%) were found in 24 of the 43 LC patients, 12 of the 14 HA patients, and 20 of the 38 HRC patients. After correction of the HbA1c values, 15 of the 24 LC patients, 9 of the 12 HA patients, and 16 of the 20 HRC patients had HbA1c values within the normal range.

CONCLUSIONS

HbA1c decreased in inverse proportion to the increase in erythrocyte creatine because of a shortened mean age of erythrocytes. The abnormally decreased HbA1c value could be assessed with erythrocyte creatine.

Sensitive enzymatic assay for erythrocyte creatine with production of methylene blue

We developed a new, highly sensitive enzymatic method for quantifying creatine in erythrocytes, which comprises creatine amidinohydrolase, sarcosine oxidase, and peroxidase. In the present method, an N-methylcarbamoyl derivative of methylene blue, 10-N-methylcarbamoyl-3,7-bis(dimethylamino)phenothiazine (MCDP), was used as a sensitive chromogenic compound. Potassium ferrocyanide was used to prevent nonspecific oxidation of MCDP. The enzymatic method exhibited good analytical performance: precision, within-run CVs <1.0% and between-day CVs <2.0%; average analytical recovery, 99.3% +/- 1.8%; detection limit, 1.0 micromol/L in hemolysate; and linearity, at least up to 500 micromol/L as creatine concentration in hemolysate. Excellent agreement was observed between the present method (y) and HPLC (x), y = 1.029x - 0.002 micromol/g hemoglobin, r = 0.9998, S(y/x) = 0.053 micromol/g hemoglobin (n = 110). No significant interference was produced by various compounds, including guanidino compounds, amino acids, and reducing materials. The reference intervals (mean +/- 2 SD) for erythrocyte creatine obtained from 60 males and 60 females were (in micromol/g hemoglobin) 1.18 +/- 0.52 (0.66-1.70) for males and 1.35 +/- 0.49 (0.86-1.84) for females. Using this method, we documented changes in erythrocyte creatine in patients with various hemolytic conditions, including hemolytic anemia, liver cirrhosis, renal insufficiency, and chronic renal failure treated with hemodialysis with or without the administration of erythropoietin. We conclude that the use of MCDP allows sensitive measurement of erythrocyte creatine and that MCDP with potassium ferrocyanide can improve the sensitivity of assays that use peroxidase for detection of H2O2.

Alterations in sheep fetal right ventricular tissue with induced hemodynamic pressure overload

We report on the cellular and molecular effects of acute and chronic hemodynamic overload on the fetal sheep heart. In one fetus of a twin gestation, the pulmonary artery was banded to create a condition of hemodynamic pressure overload in the right ventricle. The effects of this overload on the right ventricle (RV), left ventricle (LV), and intra-ventricular septum (IVS) of the heart were studied and compared to that in a control, unbanded twin fetus. At the cellular level, the histological data showed that both the size of the nuclei and the overall cell size of cardiac myocytes were increased after five days of banding; although, with one hour of banding no effects were detected at the cellular level. Based on prior studies on connexins which showed their involvement in differentiation, remodeling, and response to load we looked at their expression in control and experimental hearts. At the molecular level, changes in expression of connexin isoforms, the main gap junction protein in the heart, were observed after both one hour and five days of banding. Changes were observed in expression of connexins 40, 43, and 45. For connexin 43 there was a significant reduction confined to the right ventricle, in the chronically treated fetus, whereas, connexins 40 and 45 expression decreased after acute overload. These early molecular changes are significant because the "functional syncytium" of the myocardium is established through the gap junction connections. Alterations in connexin isoform expression affect the development, mechanical, and electrophysiological properties of the heart muscle. These changes may contribute to the ultimate result of continued hemodynamic stress on the right ventricle: heart failure.

Sequential T cell response involved in tumor rejection of sarcoma, Meth A, in syngeneic mice

We investigated the type of T cell response involved in Meth A tumor rejection in primary immune and hyperimmune syngeneic mice. It was found that a CD4+ T cell-mediated delayed-type hypersensitivity (DTH) response activating non-specific killer cells such as macrophages, NK and LAK cells, without a specific CD8+ cytotoxic T lymphocyte (CTL) response, was the major immune response leading to Meth A tumor rejection in primary immune mice. In contrast, the specific CD8+ CTL response was the major response leading to the tumor rejection, in addition to CD4+ T cell-mediated DTH response, in hyperimmune mice. Analysis of CD4+ T cell clones established from primary immune and hyperimmune spleen cells indicated that a CD4+ T cell clone (C9) of primary immune mice (although only one clone was established) was of Th1 type, and induced cytotoxicity in accessory cells by classic DTH in vitro. Eight CD4+ T cell clones were established from hyperimmune spleen cells. Six out of the eight clones were of the Th2 type and two were Th0-like. However, no Th1-type CD4+ T cell clone was established from hyperimmune spleen cells. All of these CD4+ T cell clones, even the Th2-type clones, were capable of inducing cytotoxicity in vitro in T cell-depleted accessory cells, as in an in vitro DTH response. We postulate on the basis of these results that the T cell response leading to Meth A tumor rejection in vivo sequentially changed from a CD4+ T cell-mediated classic DTH response to a CD8+ CTL response, in addition to a cellular response mediated probably by Th2-type cells, during the process of repeated immunization.

An enzymatic assay for erythrocyte creatine as an index of the erythrocyte life time

OBJECTIVES

To establish and estimate an enzymatic measurement of creatine in erythrocytes as an index of the erythrocyte life time.

DESIGN AND METHOD

The measurement of creatine in erythrocytes was performed using an enzymatic assay kit that was developed for serum and urine creatine. An erythrocyte sample was subjected to creatine measurement after hemolysis and deproteinization. Performance of the method for creatine measurement in erythrocytes was estimated. Effects of age and gender on the creatine content of erythrocytes were also estimated in 305 normal subjects.

RESULTS

The method showed within-run CVs varying from 0.7 to 1.0% (n = 20), and between-day CVs from 1.3 to 1.7% (15 days). Good linearity was observed at least up to 1000 mumol/L as creatine value in hemolyzed sample. The analytical recovery was calculated to be 98.1 +/- 1.3% on average. No considerable interference by various substances, including guanidino compounds and amino acids, with the assay was observed. Excellent correlation was observed between the present method and high performance liquid chromatography. With the unit of mumol/g Hb: slope, 1.034 +/- 0.003 (mean +/- SD); intercept, -0.059 +/- 0.012 (mean +/- SD); correlation coefficient, 0.9996; and Sy.x, 0.069. With the unit of mumol/L RBC: slope, 1.033 +/- 0.003 (mean +/- SD); intercept, -18.23 +/- 3.55 (mean +/- SD); correlation coefficient 0.9996; and Sy.x, 20.40. A significant increase in erythrocyte creatine was observed in females aged 11- to 50 years old as compared with males in the corresponding age bracket, however, a gender difference was not observed in other age bracket. This finding suggests the possibility of a slight decrease in the erythrocyte life time due to menstruation in females.

CONCLUSION

This study showed that the present method is favorable for quantifying erythrocyte creatine, and has analytical characteristics suitable for routine work in clinical laboratories.

Regulation of intracellular calcium in human esophageal smooth muscles

We have investigated sources of Ca2+ contributing to excitation of human esophageal smooth muscle, using fura 2 to study cytosolic free Ca2+ concentration ([Ca2+]i) in dispersed cells and contraction of intact muscles. Acetylcholine (ACh) caused an initial peak rise of [Ca2+]i followed by a plateau accompanied by reversible contraction. Removal of extracellular Ca2+ or addition of dihydropyridine Ca2+ channel blockers reduced the plateau phase but did not prevent contraction. Caffeine also caused elevation of [Ca2+]i and blocked responses to ACh. Undershoots of [Ca2+]i were apparent after ACh or caffeine. Blockade of the sarcoplasmic reticular Ca(2+)-ATPase by cyclopiazonic acid (CPA) reduced the ACh-evoked increase of [Ca2+]i and abolished the undershoot, indicating involvement of Ca2+ stores. When contraction was studied in intact muscles, removal of Ca2+ or addition of nifedipine reduced, but did not abolish, carbachol (CCh)-induced contraction. Elevation of extracellular K+ caused contraction that was inhibited by nifedipine, although CCh still elicited contraction. CPA caused contraction and suppressed the CCh-induced contraction, whereas ryanodine reduced CCh-induced contraction. Our studies provide evidence that muscarinic excitation of human esophagus involves both release of Ca2+ from intracellular stores and influx of Ca2+.

[The culture of TMJ condylar cartilage cells and study on their biological behaviors in vitro]

To investigate the behavoir of TMJ condylar cartilage cells in vitro, the mandibular condylar cartilage cells were harvested from a 5-month-old human fetus by dissection and sequential digestion with 0.25% trypsin and 0.2% collagenase (type II). The isolated cells were cultured in DMEM medium and identified by histochemical and immunohistochemical methods. Cell proliferation, morphology and ultrastructure were observed by phase-contrast microscope, cytologic staining and electronic microscope. In primarily cultured cells, polygonal chondroblast-like cells dominated and they were confirmed by the positive result of immunohistochemical examination for type II collagen and Toludin blue staining. In conclusion, the TMJ cells in this culture system kept their phenotype in vivo.

C-peptide does not alter carbohydrate metabolism in isolated mouse muscle

The effects of C-peptide on carbohydrate metabolism in isolated mouse soleus muscle were studied. C-peptide, at concentrations up to 1,000 nM, had no effect on [14C]glucose incorporation into glycogen, glycogen synthase activity, or 2-deoxyglucose uptake. These data demonstrate that C-peptide has no direct effect on the measured parameters of carbohydrate metabolism in isolated mouse muscle.

Intracellular calcium stores in isolated tracheal smooth muscle cells

We investigated the effects of acetylcholine (ACh) and histamine on intracellular calcium concentration ([Ca2+]i) and contraction of freshly isolated guinea pig tracheal smooth muscle cells. Previous electrophysiological studies revealed that agonists elicit cation and Cl- currents, but a role for Ca2+ in mediating these effects remains unresolved. Here we characterize agonist-induced changes of [Ca2+]i, using fura 2, and examine the contribution of the sarcoplasmic reticulum (SR) to regulation of [Ca2+]i. We provide evidence that the rise of [Ca2+]i and the contraction elicited by ACh or histamine are largely due to release of Ca2+ from stores. Agonists elicited Ca2+ transients in Ca(2+)-free solution with 0.5 mM ethylene glycol-bis (beta-aminoethyl ether)-N, N, N',N'-tetraacetic acid (EGTA), whereas prolonged exposure to Ca(2+)-free solution diminished the rise of [Ca2+]i. In addition, blockade of SR Ca(2+)-adenosinetriphosphatase (ATPase) by cyclopiazonic acid (CPA) or thapsigargin caused elevation of [Ca2+]i and reduction of ACh-evoked increase of [Ca2+]i. In many cells, [Ca2+]i fell below baseline (undershoot) after ACh or caffeine. CPA abolished this undershoot and reduced the rate of recovery of [Ca2+]i to basal levels. Furthermore, oscillations of [Ca2+]i were elicited in the presence or absence of extracellular Ca2+, and these too were reversibly abolished by CPA. Our results provide evidence that Ca2+ stores play a significant role in agonist-mediated increase of [Ca2+]i in tracheal muscle and that the SR contributes to the restoration of basal Ca2+ levels.

Development of an anthropometric database for Hong Kong Chinese CAD operators

With the increasing popularity of using computer-aided design (CAD) in Hong Kong, it is time to look into the design of a suitable workplace for the CAD operators working in the industries. This can be achieved by applying anthropometric data into the design for enhancing performance and reducing musculoskeletal problems. In order to avoid any mismatches in anthropometric dimensions, which is believed to be one of the main causes of fatigue and occupational illness among workers, in the workplace design for them, eleven relevant body dimensions from a group of 150 Hong Kong male adults with ages ranging from 18 to 28 years were collected and analyzed to develop a computerized anthropometric database for Hong Kong CAD operators. The eleven anthropometric dimensions measured were: shoulder rest height, elbow-fingertip length, shoulder breadth, hip breadth, sitting eye height, elbow rest height, third lumbar disc-pan length, thigh clearance height, popliteal height, buttock-popliteal length, and stature. The computerized database can provide some useful statistics such as mean, standard deviation and relevant percentiles of all the measured dimensions. With the aid of these statistics, a new workplace for CAD operators was designed which improved performance substantially.

[Experimental studies on Uncaria sinensis (Oliv.) Havil and Achyranthes bidentata Blume and their compacibility]

Pharmacological studies were conducted on Uncaria sinensis and Achyranthes bidentata both separately and combined. Comparison was made on the hypotensive effect on normal and renal-type hypertensive rats as well anti-spasmodic and sedative effects in mice. The results showed that Uncaria sinensis and Achyranthes bidentata have obvious synergic action in compatibility.

Identification of ochratoxin A in food samples by chemical derivatization and gas chromatography-mass spectrometry

The contamination of foods with ochratoxin A can be determined very sensitively by high-performance liquid chromatography (HPLC) with fluorescence detection. A novel procedure is described to confirm OA-positive results quantitatively down to the HPLC detection limit of 0.1 ppb. For this, ochratoxin A in the sample extract is converted into its O-methylochratoxin A methyl ester derivative, which is identified subsequently by gas chromatography-mass spectrometry negative-ion chemical ionization and multiple ion detection modes using the hexadeuterated O-methyl-d3-ochratoxin A methyl-d3 ester derivative as internal standard for quantification. In the analysis of more than 60 contaminated samples, the procedure was found to be very accurate.