A COOH-terminal peptide confers regiospecific orientation and facilitates atomic force microscopy of an IgG1

An antibody (IgG1) was designed for oriented adherence to a metal-containing surface. This was achieved by adding a metal-chelating peptide, (CP = His-Trp-His-His-His-Pro), to the COOH-terminus of the heavy chain through genetic engineering. Electroporation of the engineered heavy chain gene into cells expressing the complimentary light chain yielded colonies secreting an intact antibody containing the metal-chelating peptide (IgG1-CP) which had high affinity for a nickel-loaded iminodiacetate column. Purified IgG1-CP was bound to nickel-treated mica and imaged by atomic force microscopy (AFM). Antibody lacking the COOH-terminal metal binding peptide failed to produce discernible AFM images. The AFM images of individual IgG1-CP molecules and their calculated dimensions demonstrated that regiospecific binding and uniform orientation of the antibody was imparted by the peptide. The ability to stably orient macromolecules in their native state to a surface may be used advantageously to visualize them.

Bone mineral density in relation to anthropometric properties, physical activity and smoking in 75-year-old men and women

Bone mineral content (BMC, g.cm-2) and density (BMD, g.cm-3) were studied in 75-year-old men and women in relation to anthropometric and certain life-style factors. This study covered all the men and women born in 1914 who were residents in the city of Jyväskylä in 1989 (N = 388). A hundred and three men and 188 women participated in bone measurements performed at the calcaneus using a 125I-photon absorption method. BMC was on average 36% and BMD 17% higher in the men than in the women. BMC and BMD associated with body mass in both sexes, and with body fat and use of estrogen in the women. There was a negative correlation between the BMD values and the number of cigarettes smoked over the entire life course in both sexes. Moderate physical activity was related to higher BMC in men. Men and women who had been physically active earlier in their life tended to show higher BMD values than those who had been more sedentary.

Micromanipulation of chromosomes in PTK2 cells using laser microsurgery (optical scalpel) in combination with laser-induced optical force (optical tweezers)

An optical scalpel and optical tweezer have been combined to perform intracellular microsurgery and micromanipulation in vivo. When only laser microsurgery was performed on metaphase chromosomes, the dissected sister chromatid fragments drifted off to either the side of the spindle or completely off the spindle. At anaphase the fragments separated and the two arms generally moved to their respective daughter cells. When the chromosome arm was cut during anaphase A and B, the distal chromosome fragment separated from the rest of the chromosome and moved toward the pole, following the proximal chromosome fragment. Distal chromosome fragments laser-dissected during metaphase were held together throughout anaphase using the optical trap. Optical trapping of dissected chromosome fragments during anaphase A and B inhibited movement of the chromosome fragment to its pole. As a result, the trapped chromosome fragments were (1) incorporated into the opposite daughter cell, (2) lost in the cleavage furrow during cytokinesis, or (3) eventually incorporated into the correct daughter cell. These results indicate that optical traps are effective in holding laser-dissected chromosome fragments throughout mitosis. This new tool should be useful for studies on chromosome movement and cell genetics.

Analysis of chromosome 21 yeast artificial chromosome (YAC) clones

Chromosome 21 contains genes relevant to several important diseases. Yeast artificial chromosome (YAC) clones, because they span > 100 kbp, will provide attractive material for initiating searches for such genes. Twenty-two YAC clones, each of which maps to a region of potential relevance either to aspects of the Down syndrome phenotype or to one of the other chromosome 21-associated genetic diseases, have been analyzed in detail. Clones total approximately 6,000 kb and derive from all parts of the long arm. Rare restriction-site maps have been constructed for each clone and have been used to determine regional variations in clonability, methylation frequency, CpG island density, and CpG island frequency versus gene density. This information will be useful for the isolation and mapping of new genes to chromosome 21 and for walking in YAC libraries.

Pulmonary SP-A enhances adsorption and appears to induce surface sorting of lipid extract surfactant

The effect of surfactant concentration and supplementation with surfactant-associated protein A (SP-A) on the surface activity of lipid extract surfactant (LES) was examined using a captive bubble technique. Adsorption of LES is strongly concentration dependent over the range of 50-1,000 micrograms/ml. Addition of SP-A to LES at low concentrations in the presence of calcium dramatically increases the rate of adsorption. In quasistatic cycling experiments, samples containing SP-A require less compression to achieve low surface tensions even during the first compression cycle. Calculated film compressibilities at 15 mN/m indicate that SP-A alters the surfactant monolayer behavior such that in a small number of cycles the compressibility is indistinguishable from that of pure DPPC. Furthermore, SP-A reduces the incidence of bubble "clicking," suggesting a stabilization of the monolayer at low surface tensions. In dynamic cycling experiments, SP-A reduces compression of the film area required to achieve a low surface tension of approximately 1 mN/m. SP-A eliminated the plateau just below 25 mN/m normally observed during the compression phase with low concentrations of LES and the shoulder observed at approximately 35 mN/m during expansion. In the presence of SP-A and, to a lesser extent with high concentrations of LES, there is a marked lag in the increase in surface tension during the initial part of the dynamic expansion loop, with surface tensions remaining near 1 mN/m for approximately 10% of the increase in bubble area. The results indicate that SP-A enhances phospholipid adsorption during dynamic cycling and may enhance elimination of non-DPPC lipids during cycling.(ABSTRACT TRUNCATED AT 250 WORDS)

[Factors affecting prognosis of cryptococcal meningitis]

By analyzing 26 cases of clinic data in cryptococcal meningitis. The author found that the poor prognosis in cryptococcal meningitis depends on following factors: 1. younger age of patients, 2. abrupt onset, 3. course prolonged over 6 weeks, 4. complicated extracerebral cryptococcal infections and many underlying disease, 5. used corticosteroids and antibiotics longtime, 6. higher CSF pressure and lower CSF cells count most of which is neutrophilic leukocyte.

A morphological and immunohistochemical study of plasma cell proliferative lesions

Monoclonal plasma cell proliferative diseases such as multiple myeloma and plasmacytoma can involve extramedullary sites at the time of first presentation, or subsequently in the course of the disease. Under such circumstances, they can mimic primary or metastatic carcinomas, neuroendocrine or neuroectodermal tumours and lymphomas, and the pathologist often has to resort to immunohistochemistry as an aid to diagnosis. We studied the morphology and immunohistochemical properties of 10 cases of previously confirmed monoclonal plasma cell proliferative lesions retrieved from the files of the Department of Pathology, University of Malaya. Serial 4u thick paraffin sections were stained with H&E, the Unna-Pappenheim technique for nucleic acid and a panel of antibodies using a standard immunoperoxidase technique. Light chain restriction was demonstrable in most of the cases. Seven (70%) showed kappa and 2 (20%) lambda light chain restriction. The remaining case was not stainable with most of the antibodies in the panel. The majority (80%) of cases showed accompanying IgG heavy chain in the cytoplasm, while 1 case had IgA. Seven (70%) showed membrane positivity with antibody to epithelial membrane antigen (EMA) and 7 (70%) cytoplasmic positivity with antibody to vimentin. This study enhances our awareness that neoplastic plasma cells can be positive for EMA and vimentin, and cautions us from misinterpreting these lesions as carcinomas or sarcomas. Notwithstanding that, immunohistochemical staining for kappa and lambda light chains can be helpful in differentiating monoclonal plasma cell proliferations from polyclonal ones.

Recombinant retroviruses encoding human papillomavirus type 18 E6 and E7 genes stimulate proliferation and delay differentiation of human keratinocytes early after infection

Human papillomavirus (HPV) DNAs are detected in most genital dysplasias and cancers, suggesting that these viruses perturb epithelial growth and differentiation. The E6 and E7 genes of HPV type 18 induce immortality in keratinocytes cultured from genital tract epithelia, and the immortal cell lines display aberrant squamous differentiation. To examine whether the E6 and E7 proteins directly alter keratinocyte growth and differentiation, high-titer recombinant retroviruses were constructed for efficient transfer and expression of HPV-18 genes E6, E6* and E7 in cultures of normal human keratinocytes. Infection with retroviruses encoding E6 and E7 stimulated cell proliferation, reduced the requirement for bovine pituitary extract and induced immortality. E6 and E7 also delayed but did not prevent the onset of terminal squamous differentiation. The magnitude of effects on growth and differentiation of cultured cells was directly related to levels of E7 protein expression. Thus, expression of the HPV-18 E6 and E7 genes stimulates cell proliferation and delays differentiation of keratinocytes in vitro.

HLA-DQ beta chain can present mouse endogenous provirus MTV-9 product and clonally delete Tcr V beta 5+ and V beta 11+ T cells in transgenic mice

The elusive Mls gene(s) are mouse mammary tumor virus genes. The endogenous cotolerogen involved in the clonal deletion of Tcr V beta 5.1, 5.2, and 11 in H-2E+ mouse strains has been narrowed down to MTV-9. We demonstrate that similar to H-2E alpha molecules, human DQw6 beta chain mediated clonal deletion of Tcr V beta 5.1, 5.2, and 11 also requires the MTV-9 gene product. This shows that human class II molecules can present mouse retroviral antigen. Further, backcross analysis involving [B10.M(DQb) x DBA/1] suggest a second cotolerogen in the B10.M background in the clonal deletion of V beta 5-bearing T cells.

The ?-subunit of the skeletal muscle sodium channel is encoded proximal to Tk-1 on mouse Chromosome 11

Recent evidence suggests that the human neuromuscular disorders, hyperkalemic periodic paralysis and paramyotonia congenita, are both caused by genetic defects in the alpha-subunit of the adult skeletal muscle sodium channel, which maps near the growth hormone cluster (GH) on Chromosome (Chr) 17q. In view of the extensive homology between this human chromosome and mouse Chr 11, we typed an interspecies backcross to determine whether the murine homolog (Scn4a) of this sodium channel gene mapped within the conserved chromosomal segment. The cytosolic thymidine kinase gene, Tk-1, was also positioned on the genetic map of Chr 11. Both Scn4a and Tk-1 showed clear linkage to mouse Chr 11 loci previously typed in this backcross, yielding the map order: TrJ-(Re, Hox-2, Krt-1)-Scn4a-Tk-1. No mouse mutant that could be considered a model of either hyperkalemic periodic paralysis or paramyotonia congenita has been mapped to the appropriate region of mouse Chr 11. These data incorporate an additional locus into the already considerable degree of homology observed for these human and mouse chromosomes. These data are also consistent with the view that the conserved segment region may extend to the telomere on mouse Chr 11 and on human 17q.

Demonstration of synergistic effects of hyperthermia and photodynamic therapy using the chick chorioallantoic membrane model

The chick chorioallantoic membrane (CAM) model was used to study vascular effects of photodynamic therapy (PDT) and hyperthermia (HPT) and the synergism of these modalities. The CAM is a convenient medium for monitoring the modifications of the vasculature. It is possible to view the CAM and to examine structural changes of individual blood vessels in real time. Moreover, the CAM is a closed system which lends itself to mathematical modeling of the temporal and spatial temperature profile and in which HPT can be performed quantitatively and to a selected depth, using different lasers. A porphyrin-type photosensitizer solution was applied to areas of the CAM, defined by teflon O-rings placed on the surface. Uptake dynamics of the sensitizer into the CAM was determined by analyzing its fluorescence in vivo. The CAM area was irradiated with a dual-wavelength laser system composed of a dye laser at 644 nm (to induce PDT) and a CO2 laser at 10.6 microns (to bring about HPT). Damage to the CAM vasculature, due to combined PDT+HPT, was compared to the outcome of the separate modalities, and a synergistic effect of about 40% was observed.

Progress in studies on the antimutagenicity and anticarcinogenicity of green tea epicatechins

An antioxidative fraction was extracted from green tea and the major compounds in the fraction identified as epicatechins. Experimental results showed that green tea epicatechin compounds (GTEC) inhibited the mutagenicity and/or chromosomal damage caused by different carcinogens in both bacterial and mammalian cells. In vitro, GTEC inhibited transformation of BALB/3T3 cells induced by BP, X-rays, or MCA/TPA. In vivo, green tea extract decreased the incidence of carcinoma in the forestomach and esophagus of mice induced by sarcosine and NaNO2. GTEC inhibited the development of gamma-glutamyl transpeptidase-positive foci in the livers of rats treated with diethyl nitrosamine (DEN) or DEN/phenobarbital. Our investigations indicate that the antimutagenic and anticarcinogenic mechanisms of GTBC are related to the following: increased glutathione-S-transferase activity; inhibition of edema, hyperplasia, and ODC activity induced by TPA; free radical scavenging; blocked tumor promoter-induced inhibition of intercellular communication; and enhanced cell-mediated immunity. GTEC might be useful in the prevention of some kinds of cancer and a variety of oxidation-related diseases.

Estimates of quantitative genetic parameters of immunological traits in the chicken

Three in vivo assays were used to measure the immunocompetence of chickens in two generations of a selection experiment. The obtained data were used to estimate the variance components for sire and dam for antibody production to Pasteurella multocida and Mycoplasma gallisepticum vaccines, for T-cell-mediated immunity evaluated by a phytohemagglutinin wing web assay, and for clearance of foreign particles from the circulatory system. Heritabilities of and genetic correlations among these immunological traits were calculated from the sire variance components. Heritability estimates of the immunological traits based on the sire component of variance ranged from .06 to .53, and genetic correlations among immunological traits were generally negative.

[Analysis of leptospiral deoxyribonucleic acids by restriction endonucleases]

For the application of restriction endonuclease analysis in typing and identifying leptospira, we selected some serovars and isolates, and analysed preliminarily their DNA with four restriction enzymes, EcoR I, Bgl II, Hha I, and Hind III. The DNA samples were isolated from the reference strains and isolates as follows: Serovar lai 56601, 017 (the virulent strain for PDH model of guinea pig), Serovar autumnalis 56606, Serovar manhao II 67020, and isolates 87112 and 87369. Each 2 micrograms of DNA was digested with 20mu of restriction enzyme at 37 degrees C for 2h and electrophoresed in 0.8% agarose gel. The gels were stained in ethidium bromide and photographed with UV light. In our experiments, apparently different restriction patterns of serovar lai 017 were observed with four restriction enzymes. Serovar lai, serovar autumnalis and serovar manhao II showed different patterns with EcoR I, especially in high molecular regions. We also observed in serovar lai 017 a distinct 10.5kb band which was obscure in 56601, the reference strain of serovar lai, after EcoR I digestion. The three serovars showed some delicate differences in Hind III restriction pattern. The two isolates from Apodemus agrarius in Sichuan (1987) 87112 and 87369 had patterns identical to those of serovar lai 56601, 017 with EcoR I, and 87112 also had a pattern identical to 56601, 017 with Hind III. Our results indicate that selected three serovars can be identified by analysis of their DNA with EcoR I and Hind III. It is suggested that restriction endonuclease analysis be a good method in typing and identify leptospira and in studying the differences of special DNA molecules.

Verapamil improves rat hepatic preservation with UW solution

Verapamil, a calcium channel blocker, improves myocardial preservation during cold cardioplegia and protects against renal damage during periods of warm and cold ischemia. To determine if verapamil could prevent ischemic damage to livers during and after cold storage, harvested rat livers were flushed with either University of Wisconsin (UW) solution or UW solution with 25 mg/liter verapamil. Twenty rats were used in each group. After 24 hr of storage at 4 degrees C, livers were perfused with oxygenated blood through the portal veins for 2 hr at 37 degrees C and pH 7.4. Liver enzymes, electrolytes, and perfusate flow rate were determined at 30-min intervals. At 90 min of perfusion, the verapamil group of livers had less elevation of AST (110 +/- 17 IU/liter vs 172 +/- 25 IU/liter, P less than 0.05), ALT (115 +/- 21 IU/liter vs 210 +/- 34 IU/liter, P less than 0.05), and LDH (962 +/- 170 IU/liter vs 1452 +/- 253 IU/liter, NS). Verapamil livers produced more bile than controls (6.9 +/- 1.9 microliters/g vs 2.3 +/- 1.7 microliter/g, P less than 0.05) and maintained a higher portal flow rate throughout the perfusion. Both groups showed similar reduction in liver weights after storage (3.9 +/- 0.9% vs 2.8 +/- 0.7%) and required the same amount of bicarbonate for correction of acidosis during perfusion (2.6 +/- 0.2 mM vs 2.8 +/- 0.2 mM). Light microscopic exam after perfusion showed hepatocyte damage in 30% of control livers, but 0% of verapamil livers. We conclude that verapamil-treated rat livers showed less damage and better function upon reperfusion after 24 hr of cold storage. This agent may be clinically useful as an additive to the UW preservation solution for livers.

Effects of hydrogen sulfide exposure on surface properties of lung surfactant

Hydrogen sulfide is an irritant and chemical asphyxiant gas that exerts its primary toxic effects on the respiratory and neurological systems. Exposure to hydrogen sulfide above a threshold value of 200-300 ppm is characterized by the sudden onset of hemorrhagic pulmonary edema. The purpose of this study was to determine whether this response is associated with changes in the surface properties of pulmonary surfactant. Bronchoalveolar lavage fluid was retrieved from the lungs of Fischer 344 rats exposed to two concentrations of hydrogen sulfide or fresh air for 4 h. Surface tension-lowering properties were assayed using a captive bubble surface tensiometer. Lung injury was assessed by histopathology and measurements of total protein and lactate dehydrogenase activity in the lavagate. Marked abnormalities in surfactant activity were demonstrated in the lavagates from rats exposed to the highest concentration (300 ppm) of hydrogen sulfide. These involved the properties of adsorption to the air-water interface and surface tension lowering under quasi-static interfacial compression. Exposure to 200 ppm hydrogen sulfide had no effect on minimum surface tension despite a significant increase in protein and lactate dehydrogenase in the lavagate. This would suggest a threshold-type response for the inhibition of surfactant activity by hydrogen sulfide. In vitro studies using normal rat surfactant showed that the abnormalities in surfactant activity were due to inhibitors in the edema fluid and not to a direct effect of sulfide on surfactant. The pathophysiological consequences of increased alveolar surface tension after hydrogen sulfide exposure may need to be considered in the clinical setting.

Selecting for efficiency of egg production using food-consumption records in layer-type chickens

1. The purpose of the experiment was to evaluate the use of food consumption records in selection to improve layer-type chickens. 2. Twelve subpopulations of Leghorns, including 5878 tested birds, were used in a selection experiment which lasted 5 generations. Four were selected using an index (I1) that combined information on body weight (BW), egg-mass output (EM), and individual food-consumption records (FC). Four were selected using an index (I2) that combined information just on BW and EM. The remaining 4 served as controls, with selection differentials set to zero in each generation. 3. Differences between the selected groups, control-corrected each generation, measured the "food-record effect". 4. Including food-consumption records in the selection criterion resulted in increased body weight (7%), reduction in food consumption (6 to 9%), increase in food efficiency (egg mass/food consumption) (2 to 5%), and increase in income over food costs (10%), relative to selection not involving food records.

RecA-dependent incision of psoralen-crosslinked DNA by (A)BC excinuclease

Previous work to elucidate the mechanism of crosslink repair by (A)BC excinuclease has shown that a psoralen-crosslinked duplex is selectively incised in the furan-side strand, while a three-stranded structure is incised in the pyrone-side strand of the crosslink. These observations support a sequential incision and recombination model for the complete error-free repair of a psoralen crosslink. The work presented here extends these findings by demonstrating that in the presence of RecA protein and a homologous DNA oligonucleotide, (A)BC excinuclease is induced to incise the pyrone-side strand of a crosslinked double-stranded plasmid molecule. This finding adds further support to the current model for error-free crosslink repair.