The isolation and characterization of a specific antibody population directed against the prothrombin activation fragments F2 and F1 + 2

We have raised antisera against human prothrombin activation fragment F2 in rabbits and have chromatographed the respective immunoglobulin G fractions on prothrombin-Sepharose, Pr1-Sepharose, and F2-Sepharose immunoadsorbents. The specific antibody population obtained was utilized to construct a double antibody radioimmunoassay capable of measuring as little as 0.8 ng/ml of this component. Our studies suggest that the immunoreactive site defined by this antibody population is most probably located within the negatively charged COOH-terminal region of F2. The immunologic expression of this area is unaffected by denaturation or reduction-alkylation of F2 as well as by attachment of polypeptide to the NH2-terminal of this component. However, the presence of covalently bound polypeptide at the COOH-terminal of F2 reduces its immunologic reactivity by 300- to 400-fold. Prothrombin, Pr1, and Pr*1, which contain the F2 region as part of their covalent structure, are at least 4000 to 7000 times less immunoreactive than F2 on a molar basis. Conversion of these components to thrombin as well as activation fragments generates the theoretically predicted level of immunoreactivity. Masking of the immunoreactive site within these zymogens is due to two phenomena. Firstly, covalent attachment of polypeptides on the COOH-terminal of the F2 segment significantly depresses the reactivity of this region. Secondly, a critical S--S bridge aids in the sequenstration of the immunoreactive site. This cross-link may facilitate interactions between the COOH-terminal of the F2 segment and other regions of the zymogen.     

Combination of silver and fluorescent staining for metaphase chromosomes.

A convenient and reliable method for simulatneous visualization of silver staining (Ag-NOR) of the nucleolus organizers and fluorescent bandings in metaphase chromosomes is described. Studies employing this combined procedure on human chromosomes revealed that the Ag-NOR patterns may be characteristic for each chromosome of each individual.     

Biochemical genetic markers in the Kadazans of Sabah,Malaysia

Summary Kadazans, the largest indigenous group in Sabah, northern Borneo, were surveyed for glyoxalase I, phosphoglucomutase I, red cell acid phosphatase, esterase D, adenosine deaminase, soluble glutamate pyruvate transaminase, soluble glutamate oxaloacetate transaminase, 6-phosphogluconate dehydrogenase, uridine monophosphate kinase, adenylate kinase, peptidase B and D, superoxide dismutase, C₅, group specific component, haptoglobin and transferrin.Kadazans were found to be polymorphic for GLOI, PGMI, RCAP, esterase D, ADA, s-Gpt, 6PGD, UMPK, Gc, C₅, haptoglobin and peptidase B. Rare variants were found for transferrin and peptidase D. No variant was found for s-Got, SOD and AK.     

Alteration by methadone of catecholamine uptake and release in isolated rat adrenomedullary storage vesicles

Incubation of isolated rat adrenomedullary storage vesicles with methadone produced inhibition of ³H-epinephrine uptake and promotion of release of endogenous catecholamines. Neither effect was seen using morphine, nor could morphine antagonize methadone-induced catecholamine release, suggesting that these actions are not mediated by opiate receptors. Inhibition of uptake by methadone appeared to contain a competitive component with a lower Ki for methadone compared to the Km for ³H-epinephrine. Despite competitive inhibition by methadone, the maximal uptake capacity (analogous to Vmax) as determined by double-reciprocal plots, was increased by the drug, probably as a result of greater availability of intravesicular storage sites because of the drug-induced of release endogenous catecholamines. Agents which enhance or block catecholamine transport into vehicles had no effect on the catecholamine release by methadone, indicating that the latter is separable from the action on uptake. These alterations of catecholamine uptake and release may play a role in the effects of methadone on the adrenal medulla $\text{in vivo}$.     

Ouabain-binding vesicles from skeletal muscle.

The intact sacrospinalis (back) muscle of a rabbit was injected with [³H]ouabain and allowed to incubate for 20 min. The muscle was excised and homogenized and a microsomal preparation was made. This was placed on a sucrose density gradient and two protein bands were observed at 30 and 40% sucrose regions. Most of the [³H]ouabain was associated with the dense band. If the dense band was loaded with Ca oxalate and placed on a density gradient, then both protein and ouabain migrated equally to the bottom of the gradient. If the 40% band was treated with EDTA, both protein and ouabain migrated to 33% sucrose. It was therefore concluded that ouabain-binding vesicles were associated with the 40% band. If the 40% band was loaded with Ca oxalate and then passed through a French press and placed again on a gradient, the ouabain migrated to 22% sucrose while the protein bands appeared at 17 and 32% sucrose and in the pellet. It was concluded that ouabain-binding vesicles were distinct from the major vesicle population, but were mechanically linked until the linkage was destroyed by mechanical disruption. Electron microscopy revealed that the dense band of the gradient contained terminal cisternae and transverse tubules attached to the terminal cisternae in triad or diad junctions. It was concluded that the 40% band consisted mainly of terminal cisternae and that the ouabain-binding vesicles were transverse tubules attached to terminal cisternae. Transverse tubules therefore may be identified specifically after homogenization.     

Induction of temporary sterility in female hamsters by an intraperitoneal silastic-PVP-PGF2alpha tube.

In the female hamster, temporary sterility for a period of 10 or 15 days was induced by an intraperitoneal Silastic-PVP-tube containing 3.5 or 1.0 mg of PGF2alpha, respectively. All Silastic-PVP-PGF2alpha tube hearing animals regained fertility and delivered normal litters at various times after the placement of the tube. The release rate of 3-H-PGF2alpha from the Silastic-PVP tube was described and their potential use as a drug delivery system discussed.     

Effects of indomethacin and prostaglandin F2α on parturition in the hamster

In the female hamster, temporary sterility for a period of 10 or 15 days was induced by an intraperitoneal Silastic-PVP-tube containing 0.5 or 1.0 mg of PGF_2α, respectively. All Silastic-PVP-PGF_2α tube bearing animals regained fertility and delivered normal litters at various times after the placement of the tube. The release rate of ³H-PGF_2α from the Silastic-PVP tube was described and their potential use as a drug delivery system discussed.     

Modeling influenza seasonality in the tropics and subtropics

Climate drivers such as humidity and temperature may play a key role in influenza seasonal transmission dynamics. Such a relationship has been well defined for temperate regions. However, to date no models capable of capturing the diverse seasonal pattern in tropical and subtropical climates exist. In addition, multiple influenza viruses could cocirculate and shape epidemic dynamics. Here we construct seven mechanistic epidemic models to test the effect of two major climate drivers (humidity and temperature) and multi-strain co-circulation on influenza transmission in Hong Kong, an influenza epidemic center located in the subtropics. Based on model fit to long-term influenza surveillance data from 1998 to 2018, we found that a simple model incorporating the effect of both humidity and temperature best recreated the influenza epidemic patterns observed in Hong Kong. The model quantifies a bimodal effect of absolute humidity on influenza transmission where both low and very high humidity levels facilitate transmission quadratically; the model also quantifies the monotonic but nonlinear relationship with temperature. In addition, model results suggest that, at the population level, a shorter immunity period can approximate the co-circulation of influenza virus (sub)types. The basic reproductive number R₀ estimated by the best-fit model is also consistent with laboratory influenza survival and transmission studies under various combinations of humidity and temperature levels. Overall, our study has developed a simple mechanistic model capable of quantifying the impact of climate drivers on influenza transmission in (sub)tropical regions. This model can be applied to improve influenza forecasting in the (sub)tropics in the future.     

Perturbation of pulmonary immune functions by carbon nanotubes and susceptibility to microbial infection

Occupational and environmental pulmonary exposure to carbon nanotubes (CNT) is considered to be a health risk with a very low threshold of tolerance as determined by the United States Center for Disease Control. Immortalized airway epithelial cells exposed to CNTs show a diverse range of effects including reduced viability, impaired proliferation, and elevated reactive oxygen species generation. Additionally, CNTs inhibit internalization of targets in multiple macrophage cell lines. Mice and rats exposed to CNTs often develop pulmonary granulomas and fibrosis. Furthermore, CNTs have immunomodulatory properties in these animal models. CNTs themselves are proinflammatory and can exacerbate the allergic response. However, CNTs may also be immunosuppressive, both locally and systemically. Studies that examined the relationship of CNT exposure prior to pulmonary infection have reached different conclusions. In some cases, pre-exposure either had no effect or enhanced clearance of infections while other studies showed CNTs inhibited clearance. Interestingly, most studies exploring this relationship use pathogens which are not considered primary pulmonary pathogens. Moreover, harmony across studies is difficult as different types of CNTs have dissimilar biological effects. We used Pseudomonas aeruginosa as model pathogen to study how helical multi-walled carbon nanotubes (HCNTs) affected internalization and clearance of the pulmonary pathogen. The results showed that, although HCNTs can inhibit internalization through multiple processes, bacterial clearance was not altered, which was attributed to an enhanced inflammatory response caused by pre-exposure to HCNTs. We compare and contrast our findings in relation to other studies to gauge the modulation of pulmonary immune response by CNTs.