Prenylation of Rab5 is dependent on guanine nucleotide binding

Rab5 is a small molecular weight GTP-binding protein that functions in endocytic vesicle traffic. Like other Ras-related proteins, Rab5 is prenylated on C-terminal cysteine residues, although it lacks the typical C-terminal CAAX motif (where A is any aliphatic amino acid and X is any amino acid) to direct this post-translational modification. We have investigated structural requirements for the in vitro geranylgeranylation of Rab5. Rab5N133I, a point mutant that has impaired ability to bind GTP or GDP, undergoes modification to a limited extent and at a severely reduced rate when compared to cognate Rab5. A second point mutant, Rab5Q79L, can be processed to approximately the same extent as wild-type albeit at a reduced rate. Since the latter mutation results in defective GTPase activity, these combined observations indicate that guanine nucleotide binding plays an important role in the geranylgeranylation reaction and suggest that the GDP-bound form of Rab5 is the preferred conformation for interaction with Rab prenyltransferase. This idea is supported by the finding that non-hydrolyzable GTP analogs inhibit Rab5 prenylation, while in vitro processing of both H-ras and the gamma 2 subunit of regulatory G proteins is unaffected at concentrations of guanosine 5'-O-(thiotriphosphate) (GTP gamma S) up to 400 microM. Moreover, a truncation mutant lacking the C-terminal cysteines, Rab5(1-211), serves as an inhibitor of Rab5wt geranylgeranylation when liganded with GDP but not GTP gamma S. Thus, the recognition of Rab5 as a substrate by Rab prenyltransferase involves structural elements exclusive of the C terminus and dependent upon the GDP-binding conformation of the protein.

Treatment of twin-twin transfusion syndrome

OBJECTIVE

To determine whether therapeutic amniocentesis may improve outcomes in patients with twin-twin transfusion syndrome.

METHODS

Thirteen patients with possible twin-twin transfusion syndrome were evaluated for treatment. Therapeutic amniocenteses were performed on nine, and four patients were managed conservatively depending on the clinical severity of the twin-twin transfusion syndrome.

RESULTS

Therapeutic amniocenteses resolved the syndrome in three of nine cases, with an overall neonatal survival rate of 83.3% (15 of 18) and neonatal morbidity of 53.3% (eight of 15) among the survivors. The survival rate in patients with expectant management was 75% (six of eight), with a neonatal morbidity of 33.3% (two of six). An association between amniotic fluid status and fetal outcomes was observed. Patients with normalization of polyhydramniosoligohydramnios had the best outcomes.

CONCLUSION

Early, aggressive amniocentesis may be an effective therapy for twin-twin transfusion syndrome. Therapeutic amniocentesis may have the capability to alter inter-fetal blood flow, possibly as a result of changes in intravascular pressure, which are related to changes in intra-amniotic pressure.

Improved method for release of cell nuclei from paraffin-embedded cell material of squamous cell carcinomas

An improved method of releasing cell nuclei from paraffin-embedded highly keratinized squamous cell carcinomas by pretreatment with 85% formic acid-0.3% H2O2 followed by enzymatic treatment with subtilisin Carlsberg is described. After DAPI staining the resulting suspensions of cell nuclei were analyzed by DNA flow cytometry, in addition to microscopy. The total yield of released cell nuclei was improved and the proportion of tumor cell nuclei in the suspensions increased from 12% to 53% using this method compared to the conventional preparation technique. Cytoplasmic residue disappeared nearly completely. Thus, the finding of false aneuploid cell populations representing diploid cells with autofluorescent cytoplasm could be avoided. In addition, even small true aneuploid cell populations could be detected due to the increased proportion of released tumor cell nuclei and the lower proportion of background in the > 2C region.

Cartilage warping: an experimental model

Cadaveric cartilage was cut into blocks with a newly devised cartilage cutter. Over one-hundred pieces of cartilage were used to define a kinetics curve of cartilage warping. Kinetics curves were developed for a control group of cartilage blocks placed in saline-soaked gauze (n = 46). In addition, kinetics curves were developed for cartilage placed in hypotonic saline (n = 14), hypertonic saline (n = 14), and cyanoacrylate glue (n = 6). Photographs of all groups were taken at timed intervals in order to plot the cartilage warping. It was found that pieces of cartilage which were cut peripherally (n = 6) warped twice as much as those cut centrally (n = 40). This was significant to p = 0.001. Within 15 minutes, centrally cut pieces of cartilage warped to approximately 90 percent of their end warpage; on the other hand, peripherally cut pieces of cartilage required 30 minutes to warp 90 percent of their destined warpage. The variables used did not significantly alter the kinetics curves as compared with control.

Cross-links in cell walls of Bacillus subtilis by rotational-echo double-resonance 15N NMR

The cross-link index of peptidoglycan of intact cell walls of Bacillus subtilis grown in media containing L-[2-13C,15N]aspartic acid has been determined by rotational-echo double-resonance 15N NMR. A cross-link index of 72% decreased to 47% when the bacteria were exposed to the antibiotic cephalosporin C. The fraction of 15N label routed from aspartic acid in the media to glutamic acid in the peptidoglycan peptide stems more than doubled for the cephalosporin-exposed cells, indicating interference with general cell wall nitrogen metabolism by the antibiotic.

Effects of argipressin injected into medial amygdaloid body on blood pressure and heart rate in rats

Graded injections of argipressin (Arg, 150, 300, and 600 ng/1.5 microliters CSF, 2 min) into the medial amygdaloid body in anesthetized rats produced a dose-related increase in the mean arterial pressure and heart rate (Maximal delta MAP = 2.9 +/- 1.5 kPa, Maximal delta HR = 67 +/- 38 bpm), which lasting > 40 min at 600 ng dosage. Naloxone (15 micrograms/15 microliters CSF) injected into the lateral ventricle blocked the cardiovascular responses to Arg. These results suggest that Arg exerts a central action on the cardiovascular system via the opioid in the lateral ventricle.

Ultrastructural study of moniliformin induced lesions of myocardium in rats and mice

Effects of moniliformin on the ultrastructure of the myocardium of mice and rats were studied. Mice were given moniliformin orally at a dose of 29.46 mg.kg-1 the LD50. One h after dosing, lesions of the mitochondria of the myocardial cells were found which became more severe in 2 and 3 h. Ultrastructural lesions were also observed in the myofibrils and sarcolemma. Rats were given moniliformin orally at the dosage of 6 mg.kg-1 once daily for 56 d. Lesions of mitochondria and myofibrils were relatively mild. In the myocardiac specimens taken from the 21d post-toxin administration, lesions of the sarcolemma became more obvious. These moniliformin-induced lesions were similar to the ultrastructural changes in the myocardium of patients with Keshan disease. Our findings indicate that there may be a close and important relationship between moniliformin intoxication and Keshan disease.

Hydrogen exchange in native and alcohol forms of ubiquitin

Ubiquitin adopts a non-native folded structure in 60% methanol solution at low pH. Two-dimensional nuclear magnetic resonance (2D NMR) was used to measure the hydrogen-exchange rates of backbone amide protons of ubiquitin in both native and methanol forms, and to characterize the structure of ubiquitin in the methanol state. Protection factors (the ratios of experimentally determined exchange rates to the rates calculated for an unfolded polypeptide) for protons in the native form of ubiquitin range from less than 10 to greater than 10(5). Most of the protons that are protected from exchange are located in regions of hydrogen-bonded secondary structure. The most strongly protected backbone amide protons are those of residues comprising the hydrophobic core. Hydrogen exchange from ubiquitin in methanol solution was too rapid to measure directly by 2D NMR, so a labeling scheme was employed, in which exchange with solvent occurred while the protein was in methanol solution. Exchange was quenched by dilution with aqueous buffer after the desired labeling time, and proton occupancies were measured by 1H NMR of the native form of the protein. Protection factors for protons in the methanol form of ubiquitin range from 2.6 to 42, with all protected protons located in hydrogen-bonded structure in the native form. Again, the most strongly protected protons are those of residues in the hydrophobic core. Comparison of the patterns of the hydrogen-exchange rates in the native and methanol forms indicates that almost all of the native secondary structure persists in the methanol form, but that it is almost uniformly destabilized by 4-6 kcal/mol.(ABSTRACT TRUNCATED AT 250 WORDS)

Mutations in the V2 vasopressin receptor gene are associated with X-linked nephrogenic diabetes insipidus

X-linked nephrogenic diabetes insipidus (NDI) is a rare disorder in which the kidney is insensitive to the antidiuretic hormone, vasopressin. It has been proposed that the kidney-specific V2 vasopressin receptor, a G protein-coupled receptor, is defective in this disorder as both the disease and the receptor map to Xq28. We report six unique mutations in the V2 receptor gene of five unrelated NDI patients, with one patient having two mutations. The most severely affected patient has a nonsense mutation which would terminate the protein in transmembrane domain III. Other mutations include three missense mutations, a frameshift and one small in-frame deletion. These results represent one of the first examples of recessive mutations affecting a G protein-coupled receptor.

[A population-based study on incidence of idiopathic cardiomyopathy in Nanjing, 1985-1989]

The epidemiology of idiopathic cardiomyopathy (ICM) is largely unknown among Chinese population. The purpose of this study was to document the incidence of ICM in the entire residents aged less than 60 years in Nanjing city during the five year period from 1985 to 1989. Using the case registered method it was identified that 275 new cases of ICM collecting from all of the clinically diagnosed outpatients and inpatients in the 14 related hospitals within the city among 2,098,175 residents for years 1985-1989. Over all incidence rate was 2.6 per 100,000 person-years, the age-and sex-adjusted average annual rate being 2.1 per 100,000 directly according to the standardized population of China in 1964 (95% confidence interval 1.9-2.2). This incidence rate was increased from 1.7 per 100,000 in 1985 to 3.3 per 100,000 in 1989 and progressively increasing with aging especially in the groups over 20 years old. Among these 275 patients with ICM, 134 were classified to idiopathic dilated cardiomyopathy (IDCM) and 132 to idiopathic hypertrophic cardiomyopathy (IHCM). Both the average annual incidence rates of IDCM and IHCM were 1.3 per 100,000 and the age-and sex-adjusted rates were 1.1 per 100,000 (95% CI 0.9-1.2) in IDCN and 0.9 per 100,000 (95% CI 0.8-1.0) in IHCM, respectively. The incidence rate of ICM in male was 3.0 significantly higher than 2.2 per 100,000 in female especially in IHCM. The result of this survey is first provided with incidence data of ICM on a broad general population-based study in our country and may be of value in further studying its epidemiology and etiology.

cDNA sequence of a second fibrinogen alpha chain in lamprey: an archetypal version alignable with full-length beta and gamma chains

The message for a second fibrinogen alpha chain has been cloned from a lamprey liver cDNA library. The sequence is unique in that the amino-terminal half is homologous to all other known alpha chains, including another from lamprey, but its carboxyl-terminal half is homologous to the carboxyl-terminal portions of beta and gamma chains, segments that compose the distal globular regions of fibrinogen. The structural pattern of this newly discovered alpha chain suggests that it could be a direct descendant of the archetypal chain that existed prior to the gene duplications that led to unique beta and gamma chains and before the dislocating events that gave rise to contemporary alpha chains.

Antioxidant activity of two dibenzocyclooctene lignans on the aged and ischemic brain in rats

The effects of two dibenzocyclooctene lignans on peroxidative damage of aging and ischemic rat brain were studied. Incubation of eight-month-old rat brain mitochondria and membrane suspension with Fe(2+)-cysteine resulted in the formation of malondialdehyde (MDA) and decrease of ATPase activity. Schisanhenol (Sal) (10(-4) M) completely inhibited the peroxidative damages of brain mitochondria and membrane of rats. The swelling and disintegration of brain mitochondria, as well as the reduction of brain membrane fluidity induced by Fe(2+)-cysteine were also prevented by Sal. The results of imitative experiment of ischemia and reperfusion of brain mitochondria and membrane in vitro indicated that Sal significantly impeded production of MDA and loss of ATPase activity induced by reoxygenation following anoxia. Oral administration of Sal induced increase of cytosol glutathione-peroxidase of brain in mice under the condition of reoxygenation following anoxia. The other compound schizandrin (Sin B) also has similar activity. But its potency is weaker than that of Sal. All these results indicate that Sal and Sin B have protective action against oxidative stress.

Characterization of cross-linking of cell walls of Bacillus subtilis by a combination of magic-angle spinning NMR and gas chromatography-mass spectrometry of both intact and hydrolyzed 13C- and 15N-labeled cell-wall peptidoglycan

Cross-polarization magic-angle spinning 13C and 15N NMR, rotational-echo double resonance 13C NMR, and delays alternating with nutation for tailored excitation-difference 13C NMR spectra have been obtained from lyophilized cell walls of Bacillus subtilis grown on a synthetic medium containing D,L-[2-13C, 15N]aspartate and D-[1-13C]alanine. Label from aspartate is incorporated into D-glutamic acid and m-diaminopimelic acid of cell-wall peptidoglycan, while label from alanine appears in the C-1 positions of both D- and L-alanyl residues. The cross-link index (the fraction of peptide stems joined by an isopeptide covalent bond) is obtained directly from analysis of the results of the 13C NMR experiments. However, specific isotopic enrichments of cell-wall components cannot be obtained from NMR data alone. The latter are determined either from a gas chromatographic-mass spectrometric analysis of the amino acids derived from hydrolysis of cell-wall peptidoglycan, or from a combination of NMR and gas chromatographic-mass spectrometric results. The combined analysis is overdetermined and so involves the least error for evaluations of both the cross-link index and the isotopic enrichments. The cross-link index is 0.33 +/- 0.03 for cell walls of B. subtilis grown in the presence of the antibiotic, cephalothin.

Protection by schisanhenol against adriamycin toxicity in rat heart mitochondria

The effects of schisanhenol (Sal) on Adriamycin (ADM)-induced rat heart mitochondrial toxicity in vitro were investigated. Malondialdehyde formation, lysis, disintegration and membrane rigidification in mitochondria treated with ADM were reduced significantly by Sal. In the electron spin resonance studies, Sal did not affect significantly the formation of ADM semiquinone radicals (AQ.), whereas hydroxyl radicals generated by electron transfer from AQ.to H2O2 were scavenged by Sal dose dependently. These results indicate that Sal could protect against ADM-induced rat heart mitochondrial toxicity.

[Screening studies on anti-inflammatory function of traditional Chinese herb Gardenia jasminoides Ellis and its possibility in treating soft tissue injuries in animals]

This paper reports the study of six fractions and one chemical constituent isolated from the traditional Chinese herb Gardenia jasminoides. The results showed that two fractions (G5.G6,), alcohol extract (G1) and genipoiside(A) had obvious anti-inflammatory effects and were comparatively effective in treating soft tissue injuries in animals.

Aliphatic hydrocarbon solvents in chemically sensitive patients

The purpose of the present study was to see if chemically sensitive individuals had aliphatic hydrocarbon solvents as part of their total body load. This was done by measuring blood levels from 85 chemically sensitive patients. These were measured by a purging trap method with gas chromatography/mass spectrometry (GCC/MS) by the methods of Laseter. Thirteen patients had blood levels below the detection limit of less than 1 ppb and 72 were above the detection limit. An average of three solvents, out of seven measured, including n-pentane, 2,2-dimethylbutane, cyclopentane, 2-methylpentane, 3-methylpentane, n-hexane, n-heptane, was found in 85% of the patients' blood on the 1 to 299 ppb range. The means were as follows: n-pentane 14.7 ppb, 2,2-dimethylbutane 2.5 ppb, cyclopentane 9.0 ppb, 2-methylpentane 16.7 ppb, 3-methylpentane 28.0 ppb, n-heptane 5.5 ppb. The most frequently found of the above solvents was 2-methylpentane (found in 68.1% of the patients), 3-methylpentane (62.5%), n-hexane (61.1%), and pentane (40.3%).

Clearing of toxic volatile hydrocarbons from humans

In this study, different modes of therapy for the removal of toxic chemicals from the human body have been assessed and compared. This consisted of: 1) thirteen inpatients in an environmentally controlled area in a hospital, 2) fourty-one outpatients with home environmental control and work area change, and 3) fifteen outpatients in a physical therapy/sauna program with a good environmental control. Attention to manipulation of food, food contaminants, water and air pollution as well as nutritional therapy was important in all groups. Each modality seemed efficacious in++ its own right; 100% inpatients, 80% sauna/physical therapy patients, and 70% outpatients improved their signs and symptoms. Inpatient therapy in a finally controlled environment was far superior to the other two modalities in clearing of symptoms, as well as in clearing of organic chemicals. Outpatient and sauna/physical therapy are efficacious for less ill patients.

[Studies on the quality standards of huaijiao wan]

TLC and PC have been used in the qualitative study of huaijiao wan. The contents of the total flavones and volatile oils in huaijiao wan have been determined. The proposed method can be used to control the quality of huaijiao wan.

[Malignant tumors of the lacrimal gland--a report of 27 cases]

We report 27 cases of primary malignant tumors arising from lacrimal gland, including 12 cases with adenoid cystic carcinoma, 9 cases with malignant mixed tumor and 6 cases with other lacrimal gland carcinoma seen in Zhongshan Ophthalmic Center from 1981 to Nov. 1989. These patients with malignant neoplasms accounted for 65.85% of all patients with primary epithelial tumor of lacrimal gland. The clinical presentation, imaging features in X-ray, ultrasonic and CT scan, the diagnosis, differential diagnosis, treatment and prognosis are discussed and analysed.