Efficacy of repeated measures in regression models with measurement error

Ignoring measurement error may cause bias in the estimation of regression parameters. When the true covariates are unobservable, multiple imprecise measurements can be used in the analysis to correct for the associated bias. We suggest a simple estimating procedure that gives consistent estimates of regression parameters by using the repeated measurements with error. The relative Pitman efficiency of our estimator based on models with and without measurement error has been found to be a simple function of the number of replicates and the ratio of intra- to inter-variance of the true covariate. The procedure thus provides a guide for deciding the number of repeated measurements in the design stage. An example from a survey study is presented.

Flow cytometry for analyzing changes in irradiated and heated HeLa S3 cells

In the present study, we have compared the distribution in various phases, DNA content, cell survival and ultrastructure of HeLa S3 cells after irradiation and/or hyperthermia. After 220 KV X-ray irradiation, the Do of the survival curve was 0.94 Gy, Dq was 1.3 Gy, and N was 4.26. After Ir-192 gamma-ray irradiation, the Do of the survival curve was 2.26 Gy, Dq was 3.9 Gy, and N was 5.7. The Do of the survival curve of HeLa S3 cells after treatment at 43.5 degrees C and 44 degrees C was 2.2 min and 1.6 min, respectively. Ultrastructural changes were also observed. The marked increase of the DNA content after 6 Gy irradiation corresponded with changes of distribution in various phases, which indicated a delay in the G2 + M phase. The survival fraction after 6 Gy irradiation was less than 1%. The changes of cell cycle distribution after Ir-192 irradiation were similar to those seen after X-ray exposure. The delay of G2 + M phase after hyperthermia was dose-dependent. An obvious delay of the G2 + M phases was also observed at 24 h after treatment with X-rays plus hyperthermia.

[Benign focal epilepsy of childhood (BFEC)]

Thirty cases of benign focal epilepsy of childhood were reported. The seizures were partial or generalized motor ones in all cases. One patient had episodes of visual hallucination with motor seizures. No objective examination has demonstrated cerebral lesions in all cases. The most characteristic in the present study was that the attacks were in relation to the sleep in 90% of cases, 56.7% of all patients had nocturnal seizure only. The characteristic EEG patterns were the spike or sharp discharges in Rolandic area in 29 cases, and occipital sharps or sharp wave complexes in one patient on normal background activities. The discharge rate of Rolandic spikes or sharps were significantly higher during sleep than during the awake stage, and 12 cases had Rolandic discharges only during sleep. Sleep EEG recordings is suggested when children were suspected of having such kind of seizure type but having a normal EEG pattern when awake. Brief induced sleep is usually adequate.

Electrical stimulation of motor cortex in experimental cortical ischaemia: pyramidal responses at C5 and the surface EMG

In 7 baboons maintained under propofol anaesthesia, pyramidal tract responses were related to the corresponding peripheral EMG evoked by electrical stimulation of the motor cortex under conditions of focal cortical ischaemia. Pyramidal responses were recorded epidurally at the C5 level and the EMG was recorded from the contralateral hand or foot muscle using subdermal needle electrodes. Cortical ischaemia was produced by transorbital occlusion of the common anterior cerebral artery, and regional cortical blood flow was measured by the hydrogen clearance method. In the normally perfused brain, the later I waves of the C5 response required a lower stimulus strength to elicit them than the earlier I1 wave. It was more difficult to record the EMG from the hand than from the foot following stimulation of the corresponding cortex even though the C5 responses were always obtained in both cases. With moderate ischaemia, the later I waves were selectively abolished, leaving the D and I1 waves. EMG amplitude was significantly correlated with cortical blood flow (r = 0.88, P less than 0.005), and the threshold of cortical flow for the EMG was 10-13 ml/100 g/min. Our results indicate that changes in amplitude of the late I waves and particularly of the EMG are sensitive indicators of cortical ischaemia.

Sleep grand mal--all-night polygraphic EEG recordings in 20 cases

All-night polygraphic EEG recordings were carried out in 20 epileptic patients who are characterized as follows; 1) clinical attacks took the form of generalized tonic-clonic seizure (GTCS), which occurred only or at least 90% during sleep without other seizure types in awakening, 2) no epileptic discharges were revealed in routine EEG examinations, also including sphenoidal electrode deriving during daytime, 3) recognizable organic brain damage in these patients had been excluded by neurological examinations and CT-scan. Interictal records showed epileptiform abnormalities in 5 of the 20 patients, which were all related with NREM sleep. Four patients exhibited bilateral synchronous paroxysms of 3-3.5 Hz spike-wave short burst and only one patient had temporal-localized discharges. The results of this study demonstrated that although there was a difference compared with other reports, the most characteristic features seen in our patients diagnosed as idiopathic generalized epilepsy (IGE) were as follows: 1) less frequent SGM seizures within a year, 2) SZ onset around teen age, 3) seizures were easily evoked by some precipitating factors and 4) no recognizable organic lesions. As a conclusion, patients with an uncertain or unknown type of epilepsy should always be examined with sleep recordings and all-night sleep recordings if necessary.

[Observation of the morphological genesis of pleural mesothelioma induced by asbestos in rats]

In order to observe the lesions of pleural mesothelia caused by asbestos, we injected asbestos fiber into the pleural cavity of Wistar rats. The result showed that there Was an obvious process for the morphological genesis of mesothelioma. Simple hyperplasia and stratified pleomorphic hyperplasia of mesothelial cells were found on the 30th and 106th day after the injection of asbestos fiber, respectively. The benign and malignant mesotheliomas were noted on the 300th day. Meanwhile, a two-way differentiation may be observed in the process of mesothelial hyperplasia.

[Identification of seven snake-drugs by iso-electric point]

This paper deals with the identification of seven snake-drugs by means of iso-electric point of protein. The experimental results show that different species of snake-drugs have different iso-electric points. The experimental data are accurate and easily reproducible (CV less than 0.5%). The difference of the averages of iso-electric points of the seven snake-drugs (P less than 0.01%) is extremely significant and thus provides a scientific criterion for the identification of peeled or powdered snake-drugs.

New recombinant HLA-B alleles in a tribe of South American Amerindians indicate rapid evolution of MHC class I loci

Evidence suggests that the New World was colonized only 11,000-40,000 years ago by Palaeo-Indians. The descendants of these Palaeo-Indians therefore provide a unique opportunity to study the effects of selection on major histocompatibility complex class I genes over a short period. Here we analyse the class I alleles of the Waorani of South America and the Zuni of North America. Four of the Waorani HLA-B alleles were new functional variants which could be accounted for by intralocus recombination. In contrast, all of the Zuni HLA-A and -B molecules were present in caucasians and orientals. This suggests that the new Waorani HLA-B variants arose in South America. The description of four new HLA-B alleles in the Waorani and another five new HLA-B alleles from two other tribes of South American Amerindians indicates that the HLA-B locus can evolve rapidly in isolated populations. These studies underline the importance of gathering genetic data on endangered native human populations.

Photosynthetic electron-transfer reactions in the green sulfur bacterium Chlorobium vibrioforme: evidence for the functional involvement of iron-sulfur redox centers on the acceptor side of the reaction center

The green sulfur bacterium Chlorobium vibrioforme was cultured in the presence of ethylene to selectively inhibit the synthesis of the chlorosome antenna BChl d. Use of these cells as starting material simplified the isolation of a photoactive antenna-depleted membrane fraction without the use of high concentrations of detergents. The preparation had a BChl alpha/P840 of 50, and the spectral properties were similar to those of preparations isolated from cells grown with a normal complement of chlorosomes. The membrane preparation was active in NADP+ photoreduction. This indicated that the fraction contained reaction centers with complete electron-transfer sequences which were then characterized further by flash kinetic spectrophotometry and EPR. We confirmed that cytochrome c553 is the endogenous donor to P840+, and at room temperature we observed a recombination reaction between the reduced terminal acceptor and P840+ with a t1/2 = 7 ms. Oxidative degradation of iron-sulfur centers using low concentrations of chaotropic salts introduced a faster recombination reaction of t1/2 = 50 microseconds which was lost at higher concentrations of chaotrope, indicating the participation of another iron-sulfur redox center earlier than the terminal acceptor. Cluster insertion using ferric chloride and sodium sulfide in the presence of 2-mercaptoethanol restored both the 50-microseconds and 7-ms recombination reactions, allowing definitive assignments of these centers as iron-sulfur centers. Following the suggestion of Nitschke et al. [(1990) Biochemistry 29, 3834-3842], we associate these two kinetic phases to back-reactions between P840+ and iron-sulfur centers FX and FAFB, respectively. The iron-sulfur cluster degradation and reconstitution protocols also led to inhibition and restoration of NADP+ photoreduction by the membrane preparation, providing unequivocal evidence for the function of the centers FX and FAFB in the physiological electron-transfer sequence on the acceptor side of the Chlorobium reaction center. At 77 K we observed a recombination reaction of t1/2 = 20 ms that we suggest occurs between Fx- and P840+. Degradation of the iron-sulfur clusters resulted in replacement of the 20-ms phase with a faster reaction of t1/2 = 80 microseconds that was most likely a recombination between the early acceptor A1- and P840+ or decay of 3P840. Analysis of the iron-sulfur centers in the preparation by EPR at cryogenic temperature supports the optical measurements. EPR signals originating from the terminal acceptor(s) were not observed following treatment of the membrane preparation by chaotropes, and a modified signal was restored following cluster reinsertion.(ABSTRACT TRUNCATED AT 400 WORDS)

Oxygen-derived free radicals and hemolysis during open heart surgery

Reperfusion injury occurs during open-heart surgery after prolonged cardioplegic arrest. Cardiopulmonary bypass also is known to cause hemolysis. Since reperfusion of ischemic myocardium is associated with the generation of oxygen free radicals, and since free radicals can attack a protein molecule, it seems reasonable to assume that hemolysis might be the consequence of free radical attack on hemoglobin protein. The results of this study demonstrated that reperfusion following ischemic arrest caused an increase in free hemoglobin and free heme concentrations, simultaneously releasing free iron and generating hydroxyl radicals. In vitro studies using pure hemoglobin indicated that superoxide anion generated by the action of xanthine oxidase on xanthine could release iron from the heme ring and cause deoxygenation of oxyhemoglobin into ferrihemoglobin. This study further demonstrated that before the release of iron from the heme nucleus, oxyhemoglobin underwent deoxygenation to ferrihemoglobin. The released iron can catalyze the Fenton reaction, leading to the formation of cytotoxic hydroxyl radical (OH.). In fact, the formation of OH. in conjunction with hemolysis occurs during cardiac surgery, and when viewed in the light of the in vitro results, it seems likely that oxygen-derived free radicals may cause hemolysis during cardiopulmonary bypass and simultaneously release iron from the heme ring, which can catalyze the formation of OH..

Reduced free radical generation during reperfusion of hypothermically arrested hearts

Several studies indicate the presence of hydroxyl radical (OH.) as well as its involvement in the myocardial reperfusion injury. A transition metal-like iron is necessary for the conversion of superoxide anion (O2-) to a highly reactive and cytotoxic hydroxyl radical (OH.). In the present study, we have examined the generation of OH. and free iron in reperfused hearts following either normothermic (37 degrees C) or hypothermic ischemia (5 degrees C). Employing the Langendorff technique, isolated rat hearts were subjected to global ischemia for 30 min at 37 degrees C or 5 degrees C and were then reperfused for 15 min at 37 degrees C. The results of the study suggest that both the OH. generation in myocardium and free iron release into perfusate were significantly lower in hearts made ischemic at 5 degrees C as compared to 37 degrees C. Release of myoglobin and lactic acid dehydrogenase into perfusate also followed a similar pattern. Furthermore, in in vitro studies, chemically generated O2- at 5 degrees C caused a significantly lower rate of oxidation of oxymyoglobin as well as generation of OH. and free iron as compared to 37 degrees C. These results suggest that (1) reperfusion of hypothermic ischemic heart is associated with a reduction in the generation of OH. and cellular damage compared to that of normothermic ischemic heart, and (2) myoglobin, an intracellular protein, is a source of free iron and plays a role in the reperfusion injury mediated by free radicals.

Tyr721 regulates specific binding of the CSF-1 receptor kinase insert to PI 3'-kinase SH2 domains: a model for SH2-mediated receptor-target interactions

Efficient binding of active phosphatidylinositol (PI) 3'-kinase to the autophosphorylated macrophage colony stimulating factor receptor (CSF-1R) requires the noncatalytic kinase insert (KI) region of the receptor. To test whether this region could function independently to bind PI 3'-kinase, the isolated CSF-1R KI was expressed in Escherichia coli, and was inducibly phosphorylated on tyrosine. The tyrosine phosphorylated form of the CSF-1R KI bound PI 3'-kinase in vitro, whereas the unphosphorylated form had no binding activity. The p85 alpha subunit of PI 3'-kinase contains two Src homology (SH)2 domains, which are implicated in the interactions of signalling proteins with activated receptors. Bacterially expressed p85 alpha SH2 domains complexed in vitro with the tyrosine phosphorylated CSF-1R KI. Binding of the CSF-1R KI to PI 3'-kinase activity, and to the p85 alpha SH2 domains, required phosphorylation of Tyr721 within the KI domain, but was independent of phosphorylation at Tyr697 and Tyr706. Tyr721 was also critical for the association of activated CSF-1R with PI 3'-kinase in mammalian cells. Complex formation between the CSF-1R and PI 3'-kinase can therefore be reconstructed in vitro in a specific interaction involving the phosphorylated receptor KI and the SH2 domains of p85 alpha.

[Observation of monoclonal antibody E4B7D5 inhibitory effect on leptospiral adherence using scanning electron microscope]

BALB/c mice were immunized intraperitoneally with outer envelopes of serogroup icterohaemorrhagiae lai serovar strain 017 leptospires. Monoclonal antibody (McAb) E4B7D5 against outer envelopes (IgG1, agglutinating titre 1:25,600) was produced by hybridoma technique. Passive immunoprotection experiments have demonstrated the immunoprotection of McAb E4B7D5 against strain 017 leptospires. Effect of McAb E4B7D5 on leptospiral adherence to the surface of normal human pulmonary embryonic fibroblasts was observed by using scanning electron microscope. The results indicated that the leptospiral adherence noted in various agglutinating titre McAb E4B7D5 groups was less frequent than that in the three control groups. It was concluded that the inhibitory effect of McAb E4B7D5 on leptospiral adherence may play a role in the immunoprotection.

Comparative study of 99mTc-HM-PAO SPECT brain imaging, EEG and CT scanning in epileptic patients during the interictal period

Forty patients with epilepsy in the interictal period were studied with 99mTc (HM-PAO) SPECT brain imaging, EEG and CT scanning. Four cases of generalized epilepsy had normal findings on EEG, SPECT imaging and CT scanning. Two cases of childhood benign partial seizures had abnormal EEG, but the SPECT brain imagings were normal. Regional hypoperfusions of various extents were found in 20 of the 34 patients with complex partial seizures. Among the 34 patients, 17 had abnormal EEG and 8 had abnormal CT scans. A good topographic concordance between regional HM-PAO hypofixation and EEG foci was found (39.1%). Localization of the lesion by SPECT imaging and CT scan was coincident in 5 cases (27.8%). The correlation between these three examination methods is discussed.

Factors affecting gene expression of patatin and proteinase-inhibitor-II gene families in detached potato leaves: : Implications for their co-expression in developing tubers

In whole intact potato (Solanum tuberosum L.) plants, the gene families of class-I patatin and proteinase inhibitor II (Pin 2) are constitutively expressed in the tubers. However, they are also induced in detached potato leaves in the presence of light. To further characterize this light action, the detached leaves were subjected to monochromatic light of different wavelengths and to darkness in the presence of metabolites and inhibitors. Patatin genes could be induced by the simultaneous application of sucrose (sugars) and glutamine in darkness. Neither of these metabolites was active when supplied alone. When photosynthesis was blocked by 3-(3,4-Di-chlorophenyl)-1, 1-dimethylurea (DCMU) in the light, patatin genes were not expressed; however, the inhibition was overcome in the presence of sucrose. This indicates that besides its role in photosynthetic carbohydrate production, light may be essential for the supply of amino acids (or reduced nitrogen). Unlike patatin, Pin 2 genes were, to a small extent, also active in darkness, and sucrose weakly enhanced this expression. However, DCMU did not affect Pin 2 expression in the light. Both abscisic acid and methyl jasmonate strongly promoted the accumulation of Pin 2 mRNA independent of the light conditions, indicating that the gene family is probably under hormonal control. The phytohormones did not affect patatin gene expression. Inhibitors of cytosolic (cycloheximide) and organellar (chloramphenicol) translation had opposite effects on the two gene families. Careful evaluation of the inhibitors' action indicates that protein synthesis (cytosol) is required for the expression of Pin 2 genes but not for the patatin genes. These results clearly demonstrate that, although in situ both gene families are constitutively expressed in the same plant organ (tuber) in intact plants, their expression is mediated by different factors.

Observations of synaptic efficacy and paired-pulse facilitation in area CA1 of hippocampal slices from coriaria lactone-kindled rats

The changes of population spike(PS)/population excitatory postsynaptic potential (EPSP) slope relationship and paired-pulse facilitation (PPF) were primarily investigated with extracellular recording in stratum pyramidale to stimulation of Schaffer collaterals in CA1 region of hippocampal slices from coriaria lactone (CL)-kindled and control rats. The results were as follows: (1) neither spontaneous nor evoked epileptiform bursts were found in all hippocampal slices from CL-kindled and control rats; (2) the synaptic efficacy, expressed by the ratio of PS/EPSP slope, at low stimulation intensity ranging from 10-30% of its maximum was significantly increased on CL-kindled rats (P less than 0.05); and (3) although PPF was found in all slices, the PPF strength only at stimulation intensity of 10 and 20% of maximum was augmented remarkably in CL-kindled rats (P less than 0.002 and 0.024, respectively). According to the results from our previous work, we suggested that the increment of PS/EPSP slope ratio and PPF strength at low stimulation intensity may result from the potentiation of excitatory synaptic activity or/and the change of intrinsic excitability of pyramidal neurons.

[Review of improving the technology of processing Chinese herbal medicines]

In this paper, the present situation of processing technology for Chinese herbal medicines is expounded in all aspects. Careful processing, overall developing and comprehensive utilization are put forward as improving ways, in the hope of providing a scientific basis for carrying forward the traditional processing techniques for Chinese herbal medicines in producing areas and putting the resources to full and rational use.

[An analysis of heritability of intra-erythrocytic Na+, K+ in 139 twins]

By means of the twin model contributions of shared genes and shared environments for red blood cells Na+ and K+ were analysed by genetic and epidemiologic methods. Determination of zygosity was mainly based on examination of red blood cells system, including ABO blood group, MN blood group, P blood group, Rh blood group and secretor status of saliva, such that the probability a dizygotic pair being identical for all of these indices was less than 0.05. 139 pairs of twin in Nan Kai district Tianjin were investigated containing 74 pairs of monozygotic twins (MZ) and 65 pairs of dizygotic twins(DZ). Several methods of estimating genetic heritability (h2) were used, such as the three methods proposed by Vogel, the Holzinger's method. Levine's method based on model of variance analysis and path analysis. The degrees of compatibility of various h2 were also analysed. The contributions of shared genes, shared environments and twin's own special environments were similar for RBC Na+, h2 = 0.32, C2 = 0.35, u2 = 0.33. The contributions of shared environments were the main cause for RBC K+, C2 = 0.97.

A sequence-dependent 1H-NMR study on the formation of beta-turns in tetrapeptides containing charged residues

The importance of side-chain charge interactions in the formation of beta-turns was studied. Sixteen protected NAc-tetrapeptide amides were studied, namely the variants of DEKS: NEKS, EEKS, DDKS, DQKS, NQKS, DERS, NERS, EERS, DDRS, NDRS, DQRS, and DKES. Three tetrapeptides--NPDM, NSDM, and NDDS--were also studied as they have a high probability of forming beta-turns, based on statistical predictions. The results indicate that a small proportion of type I beta-turn exists in solutions of DEKS and DERS in methanol/water (60/40), while NEKS has an even smaller population of this turn. The other tetrapeptides are present in solution only in the extended conformation. These results clearly show the importance of the salt bridge between the side chains of K2 and E3 or R2 and E3, as well as the importance of the charge on the side chain of the first residue in stabilizing the beta-turn. The relevance of statistical predictions for beta-turns in short peptides is discussed.