Growth inhibition and regression of human prostate and breast tumors in athymic mice by tea epigallocatechin gallate

The human prostate cancer cell lines, PC-3 (androgen-insensitive) and LNCaP 104-R (androgen-repressed) were inoculated subcutaneously into nude mice to produce prostate tumors. Intraperitoneal injection of green tea (-)epigallocatechin-3-gallate but not structurally related catechins, such as (-)epicatechin-3-gallate, inhibited the growth and rapidly reduced the size of human prostate tumors in nude mice. (-)Epigallocatechin-3-gallate also rapidly inhibited the growth of tumor growth formed by the human mammary cancer cell line MCF-7 in nude mice. It is possible that there is a relationship between the high consumption of green tea and the low incidence of prostate and breast cancers in some Asian countries.

X region deletion variants of hepatitis B virus in surface antigen-negative infections and non-A, non-B hepatitis

The etiology of non-A, non-B hepatitis (NANBH) in renal dialysis patients was determined. Hepatitis C virus was present in many, but its appearance did not correlate with elevated alanine aminotransaminase. When sera from these patients were tested for antibodies against hepatitis B virus (HBV) X antigen and polymerase, 70% were positive. HBV infection was confirmed by polymerase chain reaction using several HBV-specific primer pairs. However, amplification with X region primers failed to yield products in many patients. Cloning and sequencing of these products demonstrated deletions within the X region. Hence, X-deletion variants of HBV are strongly associated with NANBH in renal dialysis patients.

The protective effects of thiopental on brain stem ischemia

Thiopental, a barbiturate anesthetic, which at high doses suppresses cortical electroencephalogram activity, was evaluated as a neuroprotective agent in a dog model of reversible, hindbrain ischemia. Fourteen dogs were exposed to 20 minutes of isolated brain stem ischemia after pretreatment with 35 mg per kg of thiopental or placebo. Brain stem auditory evoked potentials (BAEPs) and regional cerebral blood flow were measured before and during the ischemia and for 5 hours after reperfusion. During the ischemic period, both control and thiopental-treated animals experienced dramatic declines in the BAEPs to less than 10% of baseline. On reperfusion for 30 minutes, the BAEPs increased in both groups to near 40% of baseline. In the thiopental-treated animals, the BAEPs continued to recover variably to a mean of 70% of baseline by 5 hours of reperfusion. In contrast, untreated animals showed a decline in BAEPs after 30 minutes of reperfusion. The improved recovery of BAEPs in the thiopental-treated animals suggests that thiopental may be of some value as a cerebroprotective agent, although the mechanism remains unclear. The variability in recovery in this group implies that other factors play a significant role in mediating functional recovery from ischemic brain stem damage.

Parathyroid hormone (PTH)/PTH-related peptide receptor density modulates activation of phospholipase C and phosphate transport by PTH in LLC-PK1 cells

We showed previously that a single species of cloned PTH/PTH-related peptide (PTHrP) receptors, when stably expressed in LLC-PK1 kidney cells, couples to multiple second messenger signals and biological responses. To address the linkages of individual messenger signals to specific biological responses in these cells, we examined the relations among PTH/PTHrP receptor expression, PTH-activated phospholipase C (PLC) and adenylyl cyclase, and PTH-regulated phosphate transport in LLC-PK1 cells that stably express cloned rat PTH/PTHrP receptors. Among 18 such subclones, PTH stimulation of intracellular cAMP accumulation was nearly equivalent, despite differences in receptor density ranging from 20,000-400,000 sites/cell. In contrast, activation of PLC by PTH was directly and continuously dependent upon receptor density. PTH-stimulated phosphate uptake also was strongly dependent upon receptor expression, correlated well with PLC activity, was mimicked by active phorbol esters but not by cAMP analogs or forskolin, and was strikingly inhibited by the protein kinase C inhibitor, staurosporine. The peptide analog [Arg2]human PTH-(1-34), which significantly stimulated cAMP accumulation but failed to activate PLC, also did not increase phosphate uptake. We conclude that in LLC-PK1 cells, PTH-modulated PLC activation, unlike adenylyl cyclase activation, is strongly dependent upon PTH/PTHrP receptor density. This feature is reflected in the analogous relation between receptor density and PTH regulation of phosphate uptake, which appears to be mediated via a PKC-dependent pathway in these transfected cells. The results suggest that regulation of PTH/PTHrP receptor expression on target cells may provide a mechanism for altering the character as well as the magnitude of the signaling response to the hormone.

Elimination of self-peptide major histocompatibility complex class I reactivity in NOD and beta 2-microglobulin-negative mice

Nonobese diabetic (NOD) mice and beta 2-microglobulin-gene-ablated mice (beta 2M -/-) show impaired presentation of major histocompatibility complex (MHC) class I and self-peptides, structures now recognized as critical for T-cell education to endogenous peptides. The naturally occurring NOD class I presentation abnormality appears to be attributable to, in part, a quantitative defect in the production of Tap-1 mRNA; Tap-1 with Tap-2 normally functions as a transporter for stable self-peptide and class I assembly. This study attempts to reverse NOD and beta 2-M -/- mouse autoreactivity by introduced or reestablished syngeneic class I presentation. Introduction of MHC class I and self-peptides on syngeneic MHC class I-matched cells specifically prevented diabetes in NOD mice and eliminated in vitro class I-directed T-cell autoreactivity in NOD and beta 2M -/- mice. Reestablishment of endogenous class I and self-peptide presentation in NOD mice was achieved with two well-described cures for the NOD mouse, complete Freund's adjuvant and mouse hepatitis virus. Both treatments induced Tap-1 mRNA, reestablished class I presentation of endogenous antigens, and eliminated in vitro and in vivo T-cell autoreactivity of self-peptides in the class I groove. These results substantiate a therapeutic role of self-peptide complexed with class I for T-cell education and suggest that some well-described NOD treatments may work, in part, through reestablishment of tolerance through class I and self-peptide.

Studies on the relationship between changes in dietary patterns and health status

In order to study the relationship between dietary composition and health and disease, we investigated retrospectively the changes in diet composition, health status and disease specific mortality of the Shanghai population from 1950 to 1985. The results showed that remarkable changes occurred in dietary composition, health status and disease mortality. The energy from grain products decreased from 80-83% in the 1950s to 68-72% in the 1980s, and the energy from animal foods increased from 6.5-8.5% in the 1950s to 17.5-18.0% in the 1980s. With the changes in dietary composition, notable changes also occurred in the nutritional composition of the diet. From the 1950s to the 1980s, energy from fat was increased from 16.3-20.1% to 24.0-28.0%, and the energy from carbohydrates decreased from 72.0-73.5% to 62.2-65.8%. Almost certainly as a result of the changes in diet, health status and disease mortality also changed. For example, the average height in males of 18-20 years old increased from 164.89 cm in 1955 to 167.33 cm in 1974, and the average life span of males and females increased from 42.0 years and 45.6 years in 1950 to 72.1 years and 76.4 years in 1985, respectively. At the same time, the rank order of mortality causes also changed. Before 1950, the first three causes of death were measles, tuberculosis and senility, but in 1985 they were malignant tumours, cerebrovascular disease, and ischaemic heart disease. In particular, the mortality from ischaemic heart disease is now higher than in Japan. The causes of these changes may be the changes of dietary composition and nutritional composition of diet, although there are other factors. Therefore, changes in dietary composition which maintain or improve life expectancy, yet decrease the burden of chronic non-communicable disease is required.

[Effect of electric fields on the proteins in nerve regeneration conditioned fluid]

80 SD rats were randomly divided into four groups of 20 each: local electrostimulation of nerve stump (Group LS); electro-stimulation of myeloneure (Group N); electrostimulation of the denervated muscle (Group M); and controls (Group C). The left lateral sciatic nerve of rats was excised 5mm in length, and the severed nerve was bridged with the silicon tube. The gap between the stumps was about 10mm. At 3rd, 7th, 14th, 21st and 28th day after nerve transection and tube implantation, the fluid in the silicon tube was aspirated. The sample of fluid was spun and 4 microliters aliquots were taken from the supernatant. Then the electrophoresis of the aliquots was made by phase-system and assayed to the amount and variety by Gel Scan system. The results showed that the group LS had a high increase in the protein amount than others in the range of 6.16-10.23 x 10(3)D molecular weight. We believe that it is one of the mechanisms of the electric fields promoting nerve regeneration.

[Variant gap phenomenon in A-V conduction]

In 361 consecutive patients 4 with variant gap phenomenon (VGP) underwent intracardiac electrophysiological studies. The premature atrial response initially delayed in His-Purkinje system (HPS) which had a long relative refractory period (RRP), and H-V interval was prolonged. However, as atrial responses were more premature, the atrioventricular node (AVN) showed RRP and slowed down the conduction, that made HPS get rid of RRP before the response arriving. Thus the conduction resumed, and H-V interval became normal. It was different from the classic gap phenomenon. We call it variant gap phenomenon.

Time of symptom onset of eight common medical emergencies

Specific time periods of the day may be associated with different frequencies of symptom onset in different diseases. The purpose of the current study was to examine times of symptom onset in eight commonly encountered emergent conditions--cerebral infarction, cerebral hemorrhage, transient ischemic attacks, cardiac dysrhythmias, angina pectoris, acute myocardial infarction, gastrointestinal bleeding, and acute asthma. Data from 4554 cases were retrospectively reviewed. Symptom onset frequency curve diagrams were derived, illustrating peak hours of symptom presentation for each of the eight emergent conditions. Hormonal and metabolic factors that may be related to diurnal variations in symptom onset of the eight diseases are briefly discussed.

X region deletion mutants associated with surface antigen-positive hepatitis B virus infections

BACKGROUND/AIMS

The finding of antibodies against the polymerase of hepatitis B virus in renal dialysis patients before the incubation phase of infection implies underlying virus replication. Hence, the aim of the study was to test for virus during infection.

METHODS

Viremia was assayed in virus-infected and control patients using the polymerase chain reaction and Southern blotting.

RESULTS

Six months before the appearance of surface antigen, most patients had detectable core region, but few patients were X region positive. Three months after surface antigen appeared, most carriers had detectable core and X products. Three years after surface antigen appeared, 5 of 8 carriers with persistent hepatitis B e antigen and 1 of 8 carriers with corresponding antibody had these products. Cloning and sequencing showed deletions within the X/precore region of viral DNA.

CONCLUSIONS

Infection with X region mutants precedes that of wild-type virus, and they reappear after wild-type virus is eliminated in carriers.

Parent-to-child transmission is relatively common in the spread of the human polyomavirus JC virus

JC polyomavirus (JCV), the causative agent of progressive multifocal leukoencephalopathy, is ubiquitous in the human population, infecting children asymptomatically and then persisting in renal tissue. In most adults, renal JCV replicates and the progeny are excreted in urine. We used this urinary JCV to elucidate the routes of JCV transmission. A 610-bp JCV DNA region (IG region) encompassing the 3'-terminal sequences of both T-antigen and VP1 (major capsid protein) genes was amplified by means of PCR from urine specimens collected from all members of seven families. JCV strains were then unequivocally identified by the nucleotide sequences of the amplified IG regions. We could identify 18 distinctive JCV strains from 27 individuals. Different JCV strains were detected from all unrelated persons. However, the same viral strain was detected from one (four families), two (one family), or three offspring (one family) as well as from the fathers (three families) or from the mothers (three families). In total, the JCV strains detected in half of the JCV-positive children were identified in their parents. Since most humans are infected during childhood, these findings indicated that JCV is transmitted frequently from parents to children. We roughly estimated that 50% of JCV transmission occurs by this route and that the other 50% occurs outside the family.

S-(5'-deoxy-5'-adenosyl)-1-aminoxy-4-(methylsulfonio)-2-cyclopentene (AdoMao): an irreversible inhibitor of S-adenosylmethionine decarboxylase with potent in vitro antitrypanosomal activity

The S-adenosylmethionine (AdoMet) analogue S-(5'-deoxy-5'-adenosyl)-1-aminoxy-4-(methylsulfonio)-2-cycl opentene (AdoMao) was synthesized in two of its four possible diastereomeric forms using a facile chemoenzymatic route. The trans-1R,4R- and trans-1S,4S-diastereomers of AdoMao, as well as the corresponding diastereomers of the unmethylated precursor molecule nor-AdoMao, were then evaluated as inhibitors of S-adenosylmethionine decarboxylase (AdoMet-DC) from both bacterial and human sources. All four of the analogues acted as time-dependent, irreversible inhibitors of AdoMet-DC from Escherichia coli, exhibiting remarkably constant Ki values ranging between 20.6 and 23.7 microM. These analogues also inhibited the human form of AdoMet-DC, although this form of the enzyme was able to discriminate between AdoMao (Ki values of 21.2 microM for the trans-1R,4R form and 19.6 microM for the trans-1S,4S form) and nor AdoMao (Ki values of 95.2 microM for the trans-1R,4R form and 30.9 microM for the trans-1S,4S form). The trans diastereomers of AdoMao and nor-AdoMao were next evaluated for their ability to inhibit trypanosomal growth in vitro against cultured Trypanosoma brucei brucei bloodforms. All four of these analogues were effective growth inhibitors, with IC50 values ranging between 0.9 and 10.1 microM. The two most effective analogues, trans-1S,4S-AdoMao (IC50 0.9 microM) and trans-1S,4S-AdoMao (IC50 3.0 microM) were also effective against two clinical isolates of the pathogenic organism Trypanosoma brucei rhodesiense, KETRI 243 and KETRI 269. The most promising analogue in all respects was trans-1S,4S-AdoMao, which was subsequently found to have minimal effects on cell growth, AdoMet-DC activity, and intracellular polyamine levels in the sensitive human promyelocytic leukemia cell line HL60. Thus, the S-adenosylmethionine analogue trans-1S,4S-AdoMao acts as an effective inhibitor of AdoMet-DC and appears to serve as a parasite-specific trypanocidal agent in vitro.

A canine model of acute hindbrain ischemia and reperfusion

Animal models of brain stem ischemia are needed for pathophysiological study and evaluation of treatment; few such models are available currently. A new canine model of hindbrain ischemia and reperfusion is introduced in this article. Through an anterior cervical approach, the basilar artery was surgically exposed in 18 dogs. The posterior communicating and superior cerebellar arteries were embolized with cyanoacrylate glue to isolate the posterior circulation from the anterior circulation. Reversible hindbrain ischemia was induced in 14 dogs by the temporary clipping of the vertebral and ventral spinal arteries for various periods (10-30 min), then the clips were removed and reperfusion was achieved for 5 hours. In all 14 dogs, the hindbrain ischemia was confirmed by the decreased perfusion pressure in the basilar artery (< 10 mm Hg), the diminished regional cerebral blood flow as measured with a laser Doppler flowmeter at the medulla oblongata (< 10 ml/100 g/min), the flattened brain stem auditory evoked potentials, and the increased leakage of Evans blue dye from tissue. These parameters did not change in the four control dogs. The changes in brain stem auditory evoked potentials were closely related to the length of ischemic interval; after 10 minutes of ischemia, reperfusion fully reversed the changes in brain stem auditory evoked potentials, but 20-minute and 30-minute ischemic intervals partially or totally depleted the brain stem auditory evoked potentials. Delayed postischemic hypoperfusion occurred in all five dogs that underwent the 30-minute ischemic interval. The early physiological changes in this model allowed us to estimate the severity of brain stem ischemia and the resulting damage.(ABSTRACT TRUNCATED AT 250 WORDS)

Studies on affinity constants of hapten-specific monoclonal antibodies using an antibody-immobilized ELISA

An enzyme-linked immunosorbent assay to measure affinity constants of hapten-specific monoclonal antibodies has been developed. In this method an antibody-immobilizing format is used. Antibody affinity toward hapten-enzyme tracer is first calculated by using Scatchard's method. Using this affinity, antibody-hapten affinity is then calculated by following the principles of chemical thermodynamics and mass conservation. The affinity from this method agrees with the IC50 values in ELISA. This method is useful in early determination of affinity during monoclonal antibody development. Compared with the antigen-coated format, this method avoids the problem of distinguishing binding of unliganded antibody and singly liganded antibody to antigens on solid phase.

Defects in primer-template binding, processive DNA synthesis, and RNase H activity associated with chimeric reverse transcriptases having the murine leukemia virus polymerase domain joined to Escherichia coli RNase H

The RNase H domain of murine leukemia virus (MuLV) reverse transcriptase (RT) was replaced with Escherichia coli RNase H, and the effect on RNase H activity and processive DNA synthesis was studied, using RNA-DNA hybrids containing sequences from the MuLV polypurine tract (PPT). Two chimeric RTs, having the entire polymerase domain or all but the last 19 amino acids, were expressed. In both cases, these RTs made multiple cuts in PPT-containing substrates, whereas wild-type cleavages occurred primarily at sites consistent with the distance between the polymerase and RNase H active sites. Primer extension assays performed with the chimeric RTs, an RNase H-minus RT, and wild-type showed that the presence of a wild-type viral RNase H domain facilitates processive DNA synthesis. When wild-type RT was bound to primer-template, two retarded bands could be detected in band-shift assays. In the absence of primer extension, a high proportion of enzyme-bound primer-template was associated with the faster-migrating band, whereas with DNA synthesis, more of the bound radioactivity was in the super-shifted complex. This suggests that the super-shifted complex contains the active form of RT. The mutant RTs were deficient in formation of this complex, but the chimeric RTs were somewhat less defective than the RNase H-minus mutant. Our results demonstrate that in the wild-type enzyme, the RNase H domain is required to stabilize the interaction between RT and primer-template.