Lifetime risks, incubation period, and serial interval of tuberculosis

The lifetime risk of developing disease, the incubation period, and the time period between infection and transmission (the serial interval) are three important measures for interpreting trends in tuberculous infection and disease but are complicated by strong age dependencies regarding disease risk and by the potential for reinfection to occur. By using a model of the epidemiology of tuberculosis in England and Wales, the authors demonstrated that all three measures changed dramatically during the 20th century largely as a result of declines in the risk of infection. The estimated lifetime risk was highest following infection in early adulthood and declined with year of infection; the age-weighted average was approximately 12% during the last 50 years. Incubation period distributions depend on whether they are viewed prospectively (from infection to disease onset) or retrospectively (since infection for cases with disease onset at a particular time). As children rarely develop infectious forms of tuberculosis, infections acquired in childhood are associated with considerably longer serial intervals than those acquired in adulthood. These unusual properties are probably shared by other infections with long intervals between infection and disease. The results are important for interpreting data on transmission patterns, as are now being derived from molecular epidemiologic studies.     

Effect of the viable-yellow (A(vy)) agouti allele on skin tumorigenesis and humoral hypercalcemia in v-Ha-ras transgenic TGxAC mice

We previously reported that papillomas can arise from the follicular epithelium of v-Ha-ras transgenic TGxAC mice. Since the viable-yellow mutation (A(vy)) of the mouse agouti gene which regulates coat color pigmentation by acting within the micro-environment of the hair follicle has been shown to function as a tumor promoter in the liver, we hypothesized that it may also play a role in TGxAC skin tumorigenesis. Endogenous agouti protein product was detected in the outer root sheath of anagen hair follicles following plucking of the hair shaft, but not in the interfollicular epithelium, in TGxAC mice on an FVB/N genetic background. It was also detected in papillomas from these mice produced by 12-O-tetradecanoylphorbol-13-acetate (TPA) treatment or plucking. Expression of the A(vy) allele in the v-Ha-ras transgenic TGxAC mouse line results in an approximately 2-fold increase in papilloma development compared with controls which did not carry the A(vy) allele following twice-weekly treatment with 1.25, 2.5 or 5.0 microg TPA. In addition, TPA-treated, papilloma-bearing F1 mice which carried the A(vy) allele, but not F1 mice which did not carry the A(vy) allele, exhibited a syndrome of humoral hypercalcemia mediated by parathyroid hormone-related protein (PTHrP) that led to weight loss, hypercalcemia and hypophosphatemia. Thus, we conclude that the A(vy) allele can influence the development of skin tumors and PTHrP-mediated humoral hypercalcemia in v-Ha-ras transgenic TGxAC mice.      

Specular microscopic and histologic observations in nonguttate corneal endothelial degeneration

Six phakic patients with unilateral corneal edema and clinically normal-appearing fellow eyes were examined with specular microscopy and found to have endothelial pleomorphism and reduced cell counts in the nonedematous cornea. None of these patients had any previous eye disease, trauma, inflammation, or surgery. Clinically unrecognized endothelial disease was proposed as a cause for the unilateral corneal edema and was verified by light and electron microscopic studies in five patients. These pathologic findings vary somewhat from those found in Fuchs' dystrophy and may represent either a variant or a form of endothelial cell degeneration of as yet undetermined etiology. Our studies suggest that this condition is not detectable in the nonedematous cornea by standard high magnification biomicroscopy and requires the use of the clinical specular microscope to confirm the diagnosis in suspected cases.     

The natural history of serous retinal pigment epithelium detachment in patients with age-related macular degeneration

One hundred ten patients with serous detachment of the retinal pigment epithelium (RPE) were reexamined to enhance our knowledge of the natural course of this condition. All patients were greater than 50 years of age, had age-related macular degeneration, and had neither blood, lipid, nor angiographic evidence of a definite choroidal neovascular membrane (NVM) at the time of the initial examination. All patients were followed up for at least six months except for two patients who had developed a choroidal NVM within the first six months of the initial exam. Forty-five of 140 eyes (32%) developed a choroidal NVM within an average of 19.6 months (median, 12 months). This was associated with a final visual acuity of 20/200 or worse (P less than 0.0001). Ophthalmoscopic and angiographic features present at the initial visit which were associated with the development of NVM and poor final visual acuity were: sensory retinal detachment; increased size of PED; hot spot; late filling; notching; and irregular filling. At the most recent examination, 39% of the eyes had a final visual acuity of 20/20 to 20/40, while 24% of the eyes had a final visual acuity of less than or equal to 20/200.     

Scattering-driven PPG signal model

This article discusses the origin of PPG signals. Two plausible hypotheses are analyzed: the volumetric hypothesis and a model wherein the PPG is driven by the RBC aggregation process. To verify the model predictions, the PPG signals at the fingertip were measured. External pressure was applied to the fingertip, presumably reducing the blood flow. The results expressed in terms of gamma, used in pulse-oximetry, agree with the aggregation model. In addition, the oscillometric signal and the PPG signal amplitude were simultaneously measured in the fingertip. All of the experimental results favor the proposed aggregation mechanism as responsible the PPG signal.     

电感耦合等离子体原子发射光谱法分析珍宝类藏药七十味珍珠丸中汞的5种形态和分布

目的:研究藏药七十味珍珠丸中汞的5种存在形态和分布.方法:将七十味珍珠丸中汞的形态分为水溶态汞、溶于盐酸的无机汞和有机汞、络合汞、单质汞和残渣态汞,通过电感耦合等离子体原子发射光谱(ICP-AES)法分析5种形态汞的含量和分布.结果:藏药七十味珍珠丸中总汞的93.8％是以惰性汞形式存在的硫化汞,6.18％是与锌、铝、钙...