Interaction of a novel GDP exchange inhibitor with the Ras protein

Mutated, tumorigenic Ras is present in a variety of human tumors. Compounds that inhibit tumorigenic Ras function may be useful in the treatment of Ras-related tumors. The interaction of a novel GDP exchange inhibitor (SCH-54292) with the Ras-GDP protein was studied by NMR spectroscopy. The binding of the inhibitor to the Ras protein was enhanced at low Mg2+ concentrations, which enabled the preparation of a stable complex for NMR study. To understand the enhanced inhibitor binding and the increased GDP dissociation rates of the Ras protein, the conformational changes of the Ras protein at low Mg2+ concentrations was investigated using two-dimensional 1H-15N HSQC experiments. The Ras protein existed in two conformations in slow exchange on the NMR time scale under such conditions. The conformational changes mainly occurred in the GDP binding pocket, in the switch I and the switch II regions, and were reversible. The Ras protein resumed its regular conformation after an excess amount of Mg2+ was added. A model of the inhibitor in complex with the Ras-GDP protein was derived from intra- and intermolecular NOE distance constraints, and revealed that the inhibitor bound to the critical switch II region of the Ras protein.

Glutathione-related enzyme activities in human fetal adrenal, liver, and kidney

AIM

To understand the capacity of fetal adrenal to catalyze reaction metabolites.

METHODS

Subcellular fractions were prepared by differential centrifugation in fetal adrenal and liver. Glutathione (GSH)-transferase, reductase, and peroxidase were measured.

RESULTS

The mean values (mumol.min-1/g protein) of GSH-transferase activities in adrenal microsome (112 +/- 34), mitochondria (62 +/- 35), and cytosol (191 +/- 89) were 373%, 270%, and 167%, respectively, higher than those in the corresponding fractions of fetal liver. Adrenal microsomal GSH-transferase was positively correlated with adrenal microsomal P-450 (r = 0.821, P < 0.01), and with adrenal microsomal aminopyrine N-demethylase (r = 0.829, P < 0.01). The GSH reductase contents (mumol.min-1/g protein) in adrenal mitochondria (24 +/- 14), and in S9 (36 +/- 15) were almost 5 times higher, compared with that in liver. Selenium-dependent GSH peroxidase was present in all the adrenal.

CONCLUSION

Fetal adrenal, with greater capacities than those of liver in detoxifying reaction, may act as a drug-metabolizing organ during development.

The three-dimensional solution structure of the SRC homology domain-2 of the growth factor receptor-bound protein-2

A set of high-resolution three-dimensional solution structures of the Src homology region-2 (SH2) domain of the growth factor receptor-bound protein-2 was determined using heteronuclear NMR spectroscopy. The NMR data used in this study were collected on a stable monomeric protein solution that was free of protein aggregates and proteolysis. The solution structure was determined based upon a total of 1439 constraints, which included 1326 nuclear Overhauser effect distance constraints, 70 hydrogen bond constraints, and 43 dihedral angle constraints. Distance geometry-simulated annealing calculations followed by energy minimization yielded a family of 18 structures that converged to a root-mean-square deviation of 1.09 A for all backbone atoms and 0.40 A for the backbone atoms of the central beta-sheet. The core structure of the SH2 domain contains an antiparallel beta-sheet flanked by two parallel alpha-helices displaying an overall architecture that is similar to other known SH2 domain structures. This family of NMR structures is compared to the X-ray structure and to another family of NMR solution structures determined under different solution conditions.

Assessment of the insecticide carbofuran's potential to contaminate groundwater through soils in the subtropics

The possible contamination of groundwater by the insecticide carbofuran was assessed with the behavior assessment model (BAM) and groundwater pollution-potential model (GWP). Dissipation coefficients of this insecticide in two subtropical soils at different moisture contents and soil temperatures were studied by determining the degradation and adsorption of the herbicide in soils. Movement of carbofuran was studied by leaching the insecticide in a soil column in the laboratory. Under 40% field capacity and at 25 degrees C, more than 80% of carbofuran residue was found in both Luchu clay and Yuanlin silty clay loam after incubation for 63 days. The results indicate that the higher the moisture content in the soil, the less the carbofuran residue under the soil moisture below the field capacity. Carbofuran tends to dissipate more easily in Yuanlin soil than in Luchu soil. The distribution coefficient (Kd) with r2 of 0.69 and 0.92 for Luchu and Yuanlin soils, respectively, was found using the first-order kinetics law. In leaching experiment, carbofuran exhibited easier movement in Luchu than in Yuanlin soil.

[Effects of scalp acupuncture on focal cerebral ischemia in rats]

OBJECTIVE

To observe the effect of scalp acupuncture on focal cerebral ischemia in rats.

METHODS

Focal cerebral ischemia was produced in rats by the occlusion of right middle cerebral artery. The therapeutic action of scalp acupuncture on focal cerebral ischemia was studied by investigating the change of weight, neurologic symptoms, passive conditional reflex, hemorheology, infarct size of brain and pathology of brain tissue.

RESULTS

Scalp acupuncture could not only improve obviously neurologic symptoms, prolong latent period of the passive conditional reflex and lower blood viscosity, but also lessen infarct size, promote proliferation and repair of neogenetic capillary and gliocyte in the malactic and necrotic regions and reduce the edema and inflammatory reaction around the necrotic region.

CONCLUSION

Scalp acupuncture have therapeutic action on acute focal cerebral ischemia.

Detection and structural characterization of ras oncoprotein-inhibitors complexes by electrospray mass spectrometry

MS based methodology employing electrospray ionization (ESI) is described for the detection of ternary complexes in which SCH 54292 or SCH 54341 and GDP are noncovalently bound to oncogenic ras protein. The observed molecular weights of 19,816 and 19,570 Da confirmed the presence of noncovalent complexes of ras-GDP-SCH 54292 and ras-GDP-SCH 54341, respectively. We have also performed selective chemical modification of lysine residues of the ras protein complex followed by enzymatic digestion and on-line LC-ESI MS peptide mapping to determine protein-drug binding topography. There was a good correlation between nucleotide exchange inhibition as determined by the enzyme assay and evidence of complex formation as determined by MS.

Ras oncoprotein inhibitors: the discovery of potent, ras nucleotide exchange inhibitors and the structural determination of a drug-protein complex

The nucleotide exchange process is one of the key activation steps regulating the ras protein. This report describes the development of potent, non-nucleotide, small organic inhibitors of the ras nucleotide exchange process. These inhibitors bind to the ras protein in a previously unidentified binding pocket, without displacing bound nucleotide. This report also describes the development and use of mass spectrometry, NMR spectroscopy and molecular modeling techniques to elucidate the structure of a drug-protein complex, and aid in designing new ras inhibitor targets.

Induction of apoptosis and cytokine gene expression in T-cell lines by sera of patients with systemic lupus erythematosus

Accelerated apoptosis and improper expression of cytokine genes have been considered as important defects of lymphocytes for the development of systemic lupus erythematosus (SLE). This study was undertaken to test the possible contribution of serum factors obtained from SLE patients to these abnormalities. Molt-4 and Jurkat cells constantly exhibited a slower growth rate as well as more dead cells in culture with SLE sera tested than controls, although the cell cycle progression was apparently unaffected. Increased apoptosis was demonstrable among SLE sera-cultured cells by ELISA for apoptosis-specific DNA fragments and terminal deoxynucleotidyl transferase (TdT) in situ death analysis. Different levels of Fas, Fas-L, and Bcl-2 gene products were not detected between SLE sera-treated cells and the controls. The transcripts of interleukin-10 (IL-10) and interferon-gamma (IFN-gamma) genes of these two T cell lines were evidently increased in the presence of SLE sera, while IL-2 and IL-4 were unaffected. Elevated expression of IL-5 was also found in Molt-4 cells. By contrast, SLE sera reduced the transcripts of IL-6 gene in Jurkat cells. The effects of SLE sera were independent of corticosteroid medication. These results suggest that serum abnormalities may also play a role in T cell dysfunction.

Transient induction of apoptosis in serum-starved glioma cells by insulin and IGF-1

Insulin has a wide variety of biological effects. One of them is a mitogen-like activity whereby cell proliferation is stimulated. In this study we found a heretofore unreported insulin-elicited transient apoptosis of glioma cells. When serum-starved glioma cells were fed with a fresh regular medium, in the 6- to 12-h post-starvation period, the growth rate as determined by cell number was significantly suppressed by insulin, although cell cycle progression and DNA synthesis were actually accelerated. Increase in apoptosis in those growth-retarded cultures was demonstrable by Hoechst staining, detection of histone-associated DNA fragment, and in situ cell death detection. Apoptosis occurred among cells in all stages of cell cycle. After 24 h post-starvation, insulin increased the total cell number like a typical growth-promoting mitogen. In this regard, IGF-1, but not EGF nor TGF-beta 1, behaved like insulin.

[Experimental study on effects of mailuotong granule on anti-thromboangiitis obliterans]

Using experimental model of thromboangitis obliterans (TAO) in rats induced by injection of lauric acid into the femoral artery, the anti-thromboangitis obliterans effects of Mailuotong (MLT) Granule were observed. The results showed that MLT not only decreased significantly the lesion severity and extent of affected limb, plasma viscosity and level of fibrinogen, but also suppressed the arterial thrombosis, endotheliocytosis and inflammatory cell infiltration in vascular wall. MLT also reduced the organization of thrombus and facilitated thrombolysis. It showed that the therapeutic effect of MLT on TAO might be achieved by improving blood rheology, antithrombosis, thrombolysis, inhibiting endotheliocytosis and inflammatory reaction in vascular wall.

The effect of exclusive breastfeeding on development and incidence of infection in infants

Of 145 normal fullterm infants studied during the first year after birth, those exclusively breastfed for the first four months differed significantly from those not exclusively breastfed in physical and behavioral development, and resistance to infection. At four months of age, the mean weight of the exclusively breastfed group was higher (p < 0.05). At one year, the exclusively breastfed group showed more advanced. Personal-Social (p = 0.05) and gross Motor development (p < 0.05) on the Denver Developmental Screening TEst, and lesser cumulative incidence of infectious diseases (p < 0.05). This study demonstrated the beneficial effects of breastfeeding on development and resistance to infection in infants.

Chemical shift assignments and secondary structure of the Grb2 SH2 domain by heteronuclear NMR spectroscopy

The growth factor receptor-bound protein-2 (Grb-2) is an adaptor protein that mediates signal transduction pathways. Chemical shift assignments were obtained for the SH2 domain of Grb2 by heteronuclear NMR spectroscopy, employing the uniformly 13C-/15N-enriched protein as well as the protein containing selectively 15N-enriched amino acids. Using the Chemical Shift Index (CSI) method, the chemical shift indices of four nuclei, 1H alpha, 13C alpha, 13C beta and 13CO, were used to derive the secondary structure of the protein. Nuclear Overhauser enhancements (NOEs) were then employed to confirm the secondary structure. The CSI results were compared to the secondary structural elements predicted for the Grb2 SH2 domain from a sequence alignment [Lee et al. (1994) Structure, 2, 423-438]. The core structure of the SH2 domain contains an antiparallel beta-sheet and two alpha-helices. In general, the secondary structural elements determined from the CSI method agree well with those predicted from the sequence alignment.

Discrepant pattern of solid and liquid gastric emptying in Chinese patients with type II diabetes mellitus

While abnormal gastric emptying has been widely reported in patients with diabetes, its clinical relevance is still uncertain. We conducted scintigraphic gastric emptying studies in patients with Type II diabetes mellitus who had symptoms suggestive of delayed gastric emptying in an attempt to evaluate the incidence of abnormal gastric emptying and to assess the clinical parameters of the different patterns of gastric emptying. Seventy male diabetic patients were included in the study. The patients were divided into four groups according to the results of liquid and solid gastric emptying: group 1, normal liquid and solid emptying (n = 22); group 2, normal liquid but delayed solid emptying (n = 30); group 3, delayed liquid but normal solid emptying (n = 7); group 4, delayed liquid and solid gastric emptying (n = 11). To assess clinical significance, we compared duration of disease, status of blood sugar control, presence or absence of vascular complications and of peripheral neuropathy among the four groups. Of the 70 patients, 18 (25.7%) showed delayed liquid gastric emptying and 41 (58.6%) delayed solid gastric emptying. There were no significant differences in the clinical parameters of the four groups, except that patients with good sugar control were likely to have normal liquid gastric emptying. Based on the results of this study, delayed solid gastric emptying is more common than liquid gastric emptying in symptomatic Type II diabetes mellitus patients. Of the different patterns of gastric emptying, delayed liquid gastric emptying with normal solid gastric emptying is the most unusual. For Type II diabetic patients with symptoms suggestive of delayed gastric emptying, both liquid and solid gastric emptying studies should be performed.

Synthesis, antitumor activity, and chemical properties of silaplatin and related platinum (II) and platinum (IV) complexes derived from beta-silyl amines

Platinum (II) and platinum (IV) coordination complexes derived from beta-silyl-substituted amines were prepared. The solubility of selected complexes in water and physiological saline was measured, and the effect of the beta-silicon on the reactivity of the complex in aqueous solution was determined by HPLC. The stabilities of selected silyl complexes were compared to the carbon analogues. The cyclic complexes 2a ("silaplatin") and its Pt(IV) analogue, 2b, were very active against L1210 leukemia in vivo. Both the platinum (II) complex 2a and the platinum (IV) complex 2b produced a significant number of cures over the dose range 10-40 mg/kg. The platinum (II) complex 2a, silaplatin, was very active in vivo against an L1210 leukemia subline that was resistant to cisplatin; 2a was also active, when given ip, against ic implanted L1210. The cyclobutanedicarboxylic acid complex 3c was synthesized; this complex was active against both cisplatin sensitive and resistant L1210 leukemia but was less potent than the analogous dichloro compound 2a. The acyclic platinum (II) and platinum (IV) complexes 1a,b were synthesized and unexpectedly found to be inactive in vivo against L1210 leukemia. More lipophilic silaplatin analogues were prepared--Pt(II) complex 2c and Pt(IV) complex 2d have one additional methylene carbon compared to 2a,b, whereas Pt(II) complex 2e and Pt(IV) complex 2f have two additional methylene carbons. Cyclization of the alkyl groups attached to the silicon gave the spiro bicyclic Pt(II) complexes 10a and 11a and the Pt(IV) complexes 10b and 11b.

A proposal for a theory and detection method of cavitation potential of mitral bileaflet heart valve

We believe that cavitation damage to mitral bileaflet heart valve (MBHV) is caused by microcracks of hydrophobic pyrolite carbon. Our proposal is to detect cavitation potential of MBHV with an acoustic technique under various conditions of transvalvular pressures, ventricular dp/dt, leakage flow, and gas concentration in fluid, This modality, different from recent research in theory and technique, will lead to a standardized noninvasive and sufficiently sensitive technique for the detection of MBHV, to reject those valves believed to cause cavitation damage, and to develop cavitation-resistant MBHV.

Impact of alcohol consumption and cigarette smoking on stroke among the elderly in Taiwan

BACKGROUND AND PURPOSE

We investigated the influence of alcohol consumption and cigarette smoking on all types of stroke and cerebral infarction, in particular among a representative sample of elderly residents in Taiwan.

METHODS

This study was a component of a nationwide survey of health and living status of residents aged 65 years or older in Taiwan in which subjects received detailed physical, neurological, and laboratory examinations. Inquiries were made about medical history, and information on the amount and duration of drinking and smoking was obtained. Diagnoses of stroke were made according to the results of brain computed tomography at the onset of disease or were based on criteria established by the World Health Organization.

RESULTS

Of the 2600 subjects, there were 155 elderly persons with stroke (prevalence, 6%). Excessive drinking of more than 367.6 g/wk of alcohol was associated with a high prevalence of cerebral infarction. Consumption of < or = 367.5 g/wk of alcohol did not have an influence on stroke prevalence. The relationship between duration of alcohol drinking and stroke was equivocal. More than 30 pack-years of cigarette smoking was a significant risk factor for all types of stroke and cerebral infarction in particular. Using multiple logistic regression to control for possible confounders, it was found that smoking was an independent risk factors for all stroke and was of borderline significance for cerebral infarction. Although excessive drinking was a significant risk factor for cerebral infarction in univariate analysis, this effect was lost after adjustment for other confounders.

CONCLUSIONS

Cigarette smoking was a more important risk factor for stroke and cerebral infarction than excessive drinking of alcohol.

[Protrusion of thoracic intervertebral disk: report of 11 cases]

The authors reported 11 cases of thoracic intervertebral disk protrusion examined with plane film, myelography, CT and CT-myelography in 11 cases and MR imaging in 3. All of the 11, cases were confirmed by operation. There were 13 protrusions in the 11 cases with the locations of T10-11 in 4, T11-12 in 5 cases and T12-L1 in 4. 9 protrusions fell into central type, 1 into paracentral type and 1 into lateral type. The clinical symptoms were prominent with all 11 cases, however, most primary clinical diagnoses were erroneously given as lumber intervertebral disk protrusions and even the disorders of heart, lung, alimentary tract and urinary system. It was concluded that the main causes of the misdiagnosis included: (1) not easily to think of this entity for the clinic physicians due to its low incidence, (2) the untypical clinical manifestations. The authors considered that the exam method with the highest accuracy is CT-myelography.

Dissipation and movement of acaricide chlorobenzilate in the environment

The dissipation of acaricide chlorobenzilate in selected soil and river water samples was studied. Under incubation conditions at 25 degrees C and 90% field capacity of moisture for 21 days, the residues of chlorobenzilate were 14 and 55% in Lukang silty clay loam and Pincheng clay, respectively. More than 80% of chlorobenzilate remained in the natural water (pH 7.2 and 7.3, respectively) and in the water adjusted to pH 5.0 when water samples collected from Green Lake and Wai-Shuang River near Taipei were treated with chlorobenzilate and then incubated for 34 days. But when the pH was adjusted to 9.0, only 60% was found in Green Lake water and 29% in Wai-Shuang River water. The dissipation of chlorobenzilate in the soil was fitted to first-order kinetics with half-lives of 5 to 36 days under various conditions in the laboratory experiments. No chlorobenzilate was detected in the leachate by a leaching experiment on the soil column for 18 days; most chlorobenzilate remained in the upper 3 cm of the column. According to assessment by the groundwater pollution-potential model (GWP), chlorobenzilate seemed to be safe in regard to groundwater contamination.

Functional approach to treatment of back pain in primary care: a preliminary report

BACKGROUND

Back pain is one of the most common problems encountered in primary care clinics and causes great loss of work time, economy and expenditure of medical care. Knowledge of the cause of low back pain and effective treatment are rudimentary. We studied the functional approach to treatment of back pain of two acute (M:F = 1:1) and thirty chronic (M:F = 12:18) patients with back pain seen at a rural primary care clinic in September and October 1992.

METHODS

Patients were included after completing an agreement form regarding the treatment plan (emphasizing therapeutic exercise, health education and as little medication as possible) in the first interview. A primary care physician specialised in family medicine personally gave treatment to the patients with free attendance to the clinic. A functional approach was adopted in four categories-therapeutic exercise, static and dynamic body biomechanics, awareness of proprioception, and maintenance of relaxed and balanced muscle tone. The patients were encouraged to perform daily activities rather than rest.

RESULTS

Two patients with acute back pain gained complete relief without medication, modalities, equipment or other treatment one and two weeks after the first visit, respectively. Among the 30 chronic patients, after eight weeks of treatment, 12/30 (40%) gained complete relief from pain, 4/30 (13.3%) obtained more than 3/4 and less than complete relief, 7/30 (23.3%) had more than 1/2 and less than 3/4 relief, 2/30 (6.7%) gained less than 1/2 pain relief, 1/30 (3.3%) had no improvement, 1/30 (3.3%) deteriorated, and 3/30 (10%) were lost during surveillance. The patients reported no loss of work time attributed to back pain. Two acute patients visited the clinic four times and three times, respectively. The former received three prescriptions for an upper respiratory infection one month after complete remission of back pain, and the latter received no prescriptions for medication. On average, each chronic patient visited the clinic 4.83 times in 8 weeks. In only 25 of 145 (17.2%) visits was medication prescribed for other indications, and in 8 of 145 (5.5%) visits vitamin B complex or Alinamin-F for placebo was prescribed. We used neither modalities nor equipment. Only 7/30 (23.3%) patients received concurrent treatment from other medical institutions. Regarding compliance with the programmed exercise at home, two acute patients complied well. Among the 30 chronic patients, 22 (73.3%) had good compliance, 3 (10%) had poor compliance, 2 (6.7%) failed to comply and 3 (10%) were lost in follow up.

CONCLUSIONS

Treating patients with back pain in primary care clinics with a functional approach by physicians appropriately trained in primary care was a good, efficacious, economic, and practical way, although neglected elsewhere. Further research and practice in our society might be worth while.

Anaerobic biodegradability of cellulose and hemicellulose in excavated refuse samples using a biochemical methane potential assay

Improved techniques are needed to predict potential methane generation from refuse buried in landfills. The Biochemical Methane Potential (BMP) test was used to measure the methane potential of ten refuse samples excavated from a Berkeley, CA, landfill. The test was conducted in 125-ml serum bottles containing phosphate-buffered medium and inoculated with anaerobically digested sewage sludge. Comparison of the measured BMP to the theoretical BMP calculated from measured cellulose and hemicellulose concentrations indicated that cellulose plus hemicellulose is not well correlated with the measured BMP. The average of the measured to theoretical BMP was 19.1% (range 0-53%, s.d. = 16.9%). Measured sulfate concentrations showed that sulfate was an insignificant electron sink in the samples tested. Once methane production from the refuse was complete, 0.072 g of Whatman no. 1 filter paper was added to two of the four serum bottles incubated for each sample. An average of 84.9% (s.d. = 2.5%) of the added filter paper was recovered as methane, suggesting that some cellulose and hemicellulose present in refuse is recalcitrant or otherwise not bioavailable.

[A study on the pulmonary amine imaging in asthmatic patients and guinea pig asthma models]

Scintigraphic technique (SPECT) with intravenous injection of 131I-HIPDM was used to study pulmonary amine imaging in asthmatic patients and Guinea pig animal models. The results showed that the patients and animals had similar characteristic changes of amine imaging: the amine scanning pictures were not well-distributed, pulmonary amine uptake was significantly decreased but the clearance speed significantly increased as compared with those in healthy controls (P < 0.05-0.01). The only difference between the patients and the animals was that the amine imaging parameters in animals during remission recovered practically to normal, while that in patients during remission did not. The mechanism and clinical significance of the above changes were discussed.