Selected metals status in patients with noninsulin-dependent diabetes mellitus.

In order to investigate the relationships between metals zinc [Zn], copper [Cu], magnesium [Mg], or Calcium [Ca] and noninsulin-dependent diabetes mellitus, 65 patients of newly diagnosed noninsulin-dependent diabetes mellitus and 54 nondiabetic healthy controls were studied. The concentrations of selected metals in fasting blood samples and 24-h urine collections were determined. Hyperzincuria and hypermagnesuria were detected in diabetic patients (p < 0.

Activation of chicken liver dihydrofolate reductase in concentrated urea solutions.

The activation and inactivation of dihydrofolate reductase from chicken liver during denaturation in a wide concentration range of urea are compared with changes in intrinsic fluorescence. At 2 M urea the enzyme is activated 3.6-fold and is stable up to 12 h in the activated form.

Expression of two related vacuolar H(+)-ATPase 16-kilodalton proteolipid genes is differentially regulated in a tissue-specific manner.

The 16-kD proteolipid subunit is the principal integral membrane protein of the vacuolar H(+)-ATPase (V-ATPase) complex that forms the proton channel responsible for translocating protons across lipid bilayers. Two degenerate synthetic oligonucleotides, COT11 and COT12, corresponding to highly conserved transmembrane domains in all 16-kD subunits sequenced so far, were used to amplify a partial cDNA of the V-ATPase proteolipid subunit from cotton (Gossypium hirsutum L.) by polymerase chain reaction (PCR).

Inactivation during denaturation of ribonuclease A by guanidinium chloride is accompanied by unfolding at the active site.

Inactivation of pancreatic RNAase A occurs in guanidinium chloride (GdmCl) at low concentrations before the unfolding of the molecule as a whole can be detected [Liu and Tsou (1987) Biochim. Biophys. Acta 916, 455-464].

Cytokine response to respiratory syncytial virus stimulation of human peripheral blood mononuclear cells.

A key impediment to developing respiratory syncytial virus (RSV) vaccines is a lack of understanding of enhanced disease that occurred in children who received a formalin-inactivated RSV (FI-RSV) vaccine. Studies in mice have suggested that the FI-RSV vaccine induces a TH2 and live RSV induces a TH1 memory T cell response. In this study, the cytokine mRNA response of peripheral blood mononuclear cells (PBMC) from adults and children with and without previous RSV infection was characterized using a semiquantitative polymerase chain reaction (PCR).

Chaperone-like activity of protein disulfide isomerase in the refolding of a protein with no disulfide bonds.

D-Glyceraldehyde-3-phosphate dehydrogenase (GAP-DH) is a protein containing no disulfide bonds; the guanidine HCl-denatured enzyme shows only a limited extent of refolding and reactivation upon dilution, and the enzyme is particularly prone to aggregation during the dilution process. With increasing GAPDH concentration, reactivation decreases and aggregation increases. The presence of protein disulfide isomerase in the dilution mixture markedly increases reactivation of GAPDH and at the same time prevents the aggregation of GAPDH as shown by light-scattering measurements.

Inactivation precedes changes in allosteric properties and conformation of D-glyceraldehyde-3-phosphate dehydrogenase and fructose-1,6-bisphosphatase during denaturation by guanidinium chloride.

It has been shown that inactivation of several enzymes precedes overall conformational changes of the enzyme molecules as a whole during denaturation [Tsou (1993) Science, 262, 380-381]. However, the relation between inactivation, loss of allosteric properties of oligomeric enzymes and unfolding of the enzyme molecule during denaturation remain little explored. These have now been compared for D-glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and fructose-1,6-bisphosphatase (FruP2ase) during denaturation by guanidinium chloride (GdmCl).

Association and dissociation of protein disulfide isomerase.

Purified protein disulfide isomerase, homogeneous by SDS-PAGE, can be separated into two components by PAGE and by gel filtration. These two components, with the same amino-acid composition as well as N- and C-terminal sequences, are the tetramer and dimer of molecular weight 240 kDa and 120 kDa, respectively. The specific activity of the dimer is twice that of the tetramer.

A comparison of Zn(II) and Co(II) in the kinetics of inactivation of aminoacylase by 1,10-phenanthroline and reconstitution of the apoenzyme.

The kinetics of reconstitution of apoacylase with either Zn(II) or Co(II) and the inactivation of the Co(II) reconstituted enzyme by 1,10-phenanthroline (OP) has been studied by following the substrate reaction continuously in presence of the metal ion or OP respectively. Although the native Zn(II)-containing and the Co(II)-reconstituted enzymes have closely similar Michaelis constants and maximal velocities, the kinetics for both the inactivation by OP and the reconstitution of the apoenzyme with the metal ions differs considerably. For Co(II), both the inactivation by OP and the reconstitution show simple kinetics, but for Zn(II), the inhibition by OP is a multi-phasic process [Wang, Wu, Wang, Zhou and Tsou (1992) Biochem.

Protein disulfide isomerase is both an enzyme and a chaperone.

Protein disulfide isomerase (PDI) catalyzes the formation of native disulfides of peptide chains from either the reduced form or randomly joined disulfides. So that thiols situated at distant parts of the polypeptide chain can be joined together to form the native disulfides, the polypeptide chain has to be folded, at least to some extent, into the native conformation. It is suggested that PDI promotes folding of the chains as well as formation of the disulfides and plays a role similar to the chaperones in the folding process.

The evaluation of gallbladder function by quantitative radionuclide cholescintigraphy in patients with noninsulin-dependent diabetes mellitus.

Twenty-nine patients (24 males, 5 females; aged 62.8 +/- 10.1 years) with noninsulin-dependent diabetes mellitus (NIDDM) without gallstones and impaired liver function were included in our study.

Comparison of secondary structures of insulin and proinsulin by FTIR.

Although the structure of insulin is known in great detail, that of proinsulin has been little investigated, except for a few CD and NMR studies. The secondary structures of human proinsulin are now compared with those of insulin by Fourier Transformed Infrared (FTIR) studies. The deconvolved and second derivative spectra of proinsulin and insulin in the amide I' band region are closely similar with peaks corresponding to alpha-helix, irregular helix, and 3(10) helix at nearly identical positions.

Inactivation precedes conformation change during thermal denaturation of adenylate kinase.

During the thermal denaturation of rabbit muscle adenylate kinase, the extents and rates of both unfolding and aggregation are dependent on protein concentration. Under identical conditions, inactivation takes place at a lower temperature than noticeable conformational changes and aggregation as measured by fluorescence, second derivative absorption spectroscopy, far ultraviolet circular dichroism and light scattering. Kinetics of inactivation can be resolved into two phases and at the same protein concentrations, the unfolding and aggregation rates are about one order of magnitude slower than the fast phase and approximately the same as the slow phase rate of the inactivation reaction between 35 and 60 degrees C.

Inactivation before significant conformational change during denaturation of papain by guanidine hydrochloride.

During denaturation by GuHCl, papain shows a rapid decrease in activity with increasing concentrations of the denaturant followed by an intermediate stage of relatively little change from 1 to 2 M before complete inactivation at 4 M GuHCl. At GuHCl concentrations lower than 2 M, enzyme activity is more sensitive to GuHCl than noticeable conformation changes as followed by fluorescence and CD measurements. Kinetics of GuHCl inactivation were studied by following the substrate reaction in the presence of denaturant and the apparent rate constants thus obtained were found to be only slightly higher than those for conformational changes.

Bone mineral density in patients with noninsulin-dependent diabetes mellitus by dual photon absorptiometry.

Bone mineral density (BMD) in 38 male patients with noninsulin-dependent diabetes mellitus (NIDDM) was measured by dual photon absorptiometry (DPA) using a M & SE OsteoTech 300 scanner. The BMD of the second to fourth lumbar vertebrae was measured and the mean density was presented as g cm-2. The patients were distinguished according to the following three criteria: (1) blood sugar control was good or poor; (2) the duration of diabetes was long or short; (3) renal function was evaluated by effective renal plasma flow (ERPF) as good or poor.

Conformational changes at the active site of creatine kinase at low concentrations of guanidinium chloride.

It has been previously reported that, during denaturation of creatine kinase by guanidinium chloride (GdmCl) or urea [Tsou (1986), Trends Biochem. Sci. 11, 427-429], inactivation occurs before noticeable conformational change can be detected, and it is suggested that the conformation at the active site is more easily perturbed and hence more flexible than the molecule as a whole.

Structure of D-glyceraldehyde-3-phosphate dehydrogenase from Palinurus versicolor carrying the fluorescent NAD derivatives at 2.7 A resolution.

Ultraviolet irradiation of carboxymethylated D-glyceraldehyde-3-phosphate dehydrogenase leads to the formation of a fluorescent NAD derivative. The structure of the enzyme from Palinurus versicolor carrying this derivative has been determined by molecular replacement and refined using the restrained least-squares method to 2.7 A with a final crystallographic R-factor of 0.

[The evaluation of blood perfusion of lower extremities in patients with NIDDM by 133Xe muscle clearance test: a preliminary report].

In this study, we collected twenty NIDDM patients with impaired sensation and clinically suspected angiopathy over both lower extremities. All the patients underwent testing by means of the ultrasonic Doppler technique and were separated into two groups, group 1 with impaired blood flow, and group 2 with no significant impairment of blood flow. Ten normal persons were also included in this study (group 3).

[Muscle blood flow in lower limbs of healthy Chinese and variance according to sex and age].

The Xe-133 clearance method is used to measure muscle blood flow in the lower limbs to establish normal values and evaluate the variance between different sex and age groups in healthy Chinese. 99 healthy volunteers were included in this study and divided into three groups according to age and two groups according to sex. Group I: < 40 y/o, 34 persons; Group II: 41-60 y/o, 30 persons; Group III: > 60 y/o, 35 persons; male group: 51 persons; and female group: 48 persons.

[Alterations of zinc levels in patients with thyroid disorders].

It is known that patients with hyperthyroidism have a lower zinc content in their erythrocytes, and that this decrement returns to normal after treatment with anti-thyroid drugs. This study was designed to investigate the alteration of body zinc levels in thyroid disorder. Two groups of out-patients associated with hyperthyroidism or hypothyroidism, and a group of normal healthy controls were collected.