Interval effect of beta-irradiation and subsequent 4-nitroquinoline 1-oxide painting on skin tumor induction in mice

Skin tumors were produced in female ICR mice by 90Sr-90Y beta-irradiation and subsequent 4-nitroquinoline 1-oxide painting. The doses were chosen so as to produce no tumors with a single agent alone; the interval between two treatments ranged from 11 to 408 days. The tumor induction rate was found to be at almost the same level (average, 12.4%) for each interval. The results indicate the persistence of the latent carcinogenic alterations in the beta-irradiated mouse skin.     

Use of skin electrogastrography for the gastrointestinal system evaluation

The major histocompatibility complex (MHC) in man, the HLA-complex, is for its marked significance in the regulation of immune system reactions and for its important role in clinical medicine the object of incessant interest for further studies. There is also a constant search for new methods of HLA typing. HLA antigens have been traditionally detected by serological and cellular methods. Recently HLA typing methods based on DNA typing utilising polymerase chain reaction (PCR) are being introduced. PCR-SSO (sequence-specific oligonucleotide) and PCR-SSP (sequence-specific primers) methods are most frequently used for routine typing of HLA class I alleles. We present technical details of the PCR-SSP method, recently introduced at our department and a short review of other techniques. (Fig. 1, Ref. 34.)     

固溶处理对Al-Cu-B合金组织的影响

铝铜合金中加入不同含量的B,在相同的熔炼工艺及固溶处理条件下,获得不同的组织。XRD、SEM、金相显微镜对显微组织以及布氏硬度分析,结果表明:显微组织主要为α固溶体和θ相(Al_2Cu)以及AlB_2。硼含量增加,硬度增大,θ相(Al_2Cu)逐渐由网状变为半网状,AlB_2等硼化物的弥散数目增多,当硼含量超过0.42%时,出现硼化物的偏聚,导致硬度降低。合金在540℃固溶后,布氏硬度逐渐变大,15 h时含硼铝铜合金硬度达到峰值120HBS,在24 h时达到另一峰值129HBS。     

The effect of cooling rate on the microstructures formed during solidification of ferritic steel

This article describes in detail the effect of cooling rate on the microstructure of a low-carbon Fe-12 pct Cr alloy. The alloy was prepared using a relatively simple technique, i.e., rapid cooling of the melt in a copper wedge mold. The dependence of microstructure on the cooling rate (∼40 to 10⁵ K/s) has been determined by X-ray diffraction (XRD), microhardness measurement, optical microscopy (OM), and transmission electron microscopy (TEM). It has been found that the matrix structure over a large cooling rate range is composed of columnar ferrite grains, the size of which decreases with increasing cooling rate. Precipitation of second phases has been observed at either the ferrite grain boundaries or within the ferrite grains. The former takes place along the entire wedge sample, whereas the latter characterizes a region 12 mm away from the tip of the wedge sample. The essential structure of the grain boundary precipitates was identified as martensite, which is a transformation product of austenite precipitated at high temperatures. Retained austenite was identified at the tip region as isolated particles (<4 μm). The precipitates within the ferrite grains appeared as planar colonies consisting of two sets of needles. The density of these precipitates increases with increasing the cooling rate while their size decreases. Characteristic precipitate-free zones (PFZs) at the ferrite grain boundaries were observed and are discussed.     

The effect of ranitidine on the tuberculin skin test

The previously unreported occurrence of dysbaric osteonecrosis in an amateur sport scuba diver who had no other identified cause of avascular bone necrosis is described.     

Overview of non-destructive evaluation of steel microstructures using multifrequency electromagnetic sensors

Abstract

The characterisation of steel microstructures is an important tool for metallurgists as mechanical properties are controlled by microstructural parameters such as grain size, phase balance and precipitates. The majority of microstructural characterisation tools are indirect (inference from measurement of temperature), destructive (optical metallography, SEM and X-ray) or require small samples and laboratory equipment (dilatometry and DSC). This paper describes a multifrequency electromagnetic sensor that has been designed to detect changes in the relative permeability and resistivity of steel, which can be related directly to changes in microstructure. COMSOL multiphysics modelling software, considering the sensor design, sample geometry and sample microstructure, has been used to relate the measured sensor signal to changes in the steel microstructure. Examples presented in this paper are where the sensor has been used to monitor phase transformation (austenite to ferrite) below the Curie temperature (～770°C) during online processing of steel; detection of decarburisation, both online and offline; and evaluation of the effect of long term thermal exposure on alloyed steels (changes in martensitic/bainitic microstructures).     

Comparative analysis of the cellular and Johnson-Mehl microstructures through computer simulation

The geometric properties of polygranular microstructures of the Johnson-Mehl cellular types have been studied through computer simulation. These prototypic microstructures arise naturally from the classical model of a phase transformation in a one-component solid through growth from a random distribution of nucleation sites. The Johnson-Mehl microstructure results in the kinetic limit of a constant nucleation rate over an essentially constant density of available nucleation sites; the cellular microstructure is produced in the kinetic limit of simultaneous activation of the available nucleation sites. Members of each of these microstructure types are similar to one another in all aspects of their geometrical statistics; they differ only through a homogeneous expansion or contraction. Their geometric features have been characterized through a combination of analytic and computer simulation studies. Comparison with available experimental results shows that the Johnson-Mehl microstructure compares well with such metallurgically diverse experimental structures as the crystallization structure of silicon iron and the intermediate structures established during the ordering of lithium ferrite. These correspondences suggest that the idealized microstructures studied here may be physically relevant as well as being pedagogically useful.     

Current viewpoints on the evaluation of testicular biopsy]

The aim of this study was to analize clinical diagnoses and histopathological reports in 185 cases of male infertility, investigated by testicular biopsies in the period 1993-1997. The classical objective of such investigations has been to clarify either obstructive, or so-called secretory lesions resulting in azoospermia. Histologically normal spermatogenesis was reported in 8 patients (4.3%). Hypospermatogenesis proved to be the most frequent pathologic lesion (69 cases, 37.3%), followed by maturation arrest (61 cases, 33%). Germ cell aplasia (Sertoli-cell-only syndrome) was found in 28 cases (15.1%). Tubular atrophy was the dominant lesion in 5 cases (2.7%). Inflammatory change without other histologic abnormalities was seen only in 1 biopsy (0.5%). Further 13 specimens (7%) showed miscellaneous lesions, including one intratubular germ cell neoplasia. Retrospective histopathologic analysis revealed the coexistence of different basic lesions in 43 of our cases (21.7%). According to the novel requirements, pathologists should always report the presence of germ cell forms in the specimen, which are potentially suitable for fertilization. This is essencial because the new methods of testicular spermium extraction and intracytoplasmatic spermium injection offer the chance of assisted fertilization, even for some patients with smaller testicles and slightly elevated FSH levels.     

Computer analysis of nystagmus

An algorithm for the computer analysis of nystagmus is described in this paper. This algorhythms was based on digital differentiator, which monitors the eye position. The computed eye velocity is next used as an input to the fast phase detector. Several procedures, including minimum velocity test, slope sense test, SPV and FPV relationship test are invoked to extract the fast phases from the recorded signal. Based on three-years experience (approx. 3000 examinations) using the ENG-PC System in clinical practice we can conclude, that application of the nystagmus detector was useful in most cases. In our opinion, despite from system imperfection which is observed during the analysis of recording disturbed by artifacts, this system has unquestionable advantage over the traditional technique.     

Development of a computer-assisted thermoelectric Peltier cold test procedure with integrated photoplethysmography unit for noninvasive evaluation of acral skin circulation]

Local cold provocation tests are an important, non-invasive diagnostic tool for collecting information about skin perfusion during exposure to cold. In patients suffering from vasospastic circulatory disorders such as Raynaud's phenomenon, it is of particular importance to be able to collect data about acral circulation during the cooling test in the asymptomatic intervals between naturally occurring attacks. By carrying out a series of cold provocation tests, for example, patient response to a newly initiated therapy can be assessed. Here we present a recently developed, computer-aided thermoelectric Peltier device with an integrated finger holder for carrying out local cold provocation tests. The electronic control unit of the Peltier element make it possible to cool or heat to predefined temperatures. At the same time, the temperature of both the finger holder and the skin can be measured. A photoplethysmographic sensor is also integrated within the device, enabling the response of the pulse waves to the controlled temperature changes to be monitored accurately. It is also possible to measure simultaneously laser Doppler flux and capillary pressure in the nailfold and to perform nailfold capillaroscopy to determine red blood cell velocity. The new device provides us with the technical means to study the interrelationship between acral skin perfusion and the thermal regulation of the skin.     

The effect of reduced gravity on solidification microstructures of NH4Cl-H2O alloys

The effect of gravity on the columnar-to-equiaxed microstructural transition was studied in small samples of NH₄Cl-H₂O. The behavior of the samples during laboratory (one gravity) experiments was contrasted with their behavior during a (low gravity) sounding rocket flight. In one gravity, the columnar zone accounted for 25 to 100 pct of the structure, depending on the superheat and orientation of the chill. Grain multiplica-tion occurred by showering and by convection induced dendrite arm remelting. Convec-tion was caused by both thermal gradients and solutal gradients. In low gravity, however, completely columnar structures were obtained; all grain multiplication mechanisms were entirely suppressed. Reduced gravity also modified the thermal conditions and caused the liquid to cool more slowly. This resulted in a steeper temperature gradient in the liquid ahead of the solidification interface. “Big bang” type nucleation occurred in two of the samples, distributing nuclei throughout the liquid. Despite this, an equiaxed zone did not form, indicating that the most significant effect of low gravity on this experiment was modification of the thermal conditions.     

Computer evaluation of second tarsometatarsal joint dislocation

Using computer-assisted techniques, this study analyzes the mean contact area of the articular surface of the second tarsometatarsal joint. The articular contact area decreased proportionate to the displacement in both males and females, but it was consistently greater in males than in females for all simulated displacements. The reduction in the contact area was the highest with dorsolateral displacement compared with the lateral and dorsal displacements. Dorsolateral displacement of the second metatarsal of 3 mm led to 38.6% reduction in the contact area, compared with 33.1% and 20.2% reduction with lateral and dorsal displacements, respectively. This study shows that even minor degrees of displacement not apparent on plain radiographs lead to significant decrease in the contact area of the second tarsometatarsal joint. Careful evaluation of second tarsometatarsal injuries with computed tomography is recommended to detect minor degrees of displacement.     

Computer simulation of the effect of coherency strain on cluster growth kinetics

To understand clustering behavior under the influence of a coherency strain, Monte Carlo simulations were carried out for both two-dimensional (2-D) square and three-dimensional (3-D) simple cubic lattices. In the Monte Carlo model, each solute was assumed to exert coherency stress owing to a tetragonal misfit strain and to have surface energy when in contact with solvent atoms. To account for the coherency strain of a cluster whose morphology continuously changes during aging, exact expressions for both the self-strain energy and elastic interaction term for rectangular parallelepipeds were derived. Strong elastic interactions among platelike clusters are shown to develop a stabilized structure with a tendency for bridging the clusters at a right angle. In the early stage of evolution, solute atoms were found to diffuse into regions of stress concentration. Morphological changes revealed step movements on the edge of a cluster, and some steps were moving in the direction of dissolution (rather than growth) for the cluster, thus displaying a dynamic nature of step movement. When an initial shape was an elastically unstable one, a large cluster was found to dissolve into its solid solution, while, in the same environment, a cluster of the same size with a stable morphology sustained growth. During dynamic evolution, some clusters showed concave, instead of convex, surfaces, even though the former are highly nonequilibrium shapes. This paper is based on a presentation made in the symposium “The Role of Ledges in Phase Transformations” presented as part of the 1989 Fall Meeting of TMS-MSD, October 1–5, 1989, in Indianapolis, IN, under the auspices of the Phase Transformations Committee of the Materials Science Division, ASM INTERNATIONAL.     

Echographic evaluation with image analysis of normal skin: variations according to age and sex

In order to identify and characterize the sonographic variations between different age groups, 48 subjects, 24 aged 27-30, and 24 over 60, were studied with a 20-MHz B scanner on six skin sites. Images were evaluated by the instrument's standard programme and by a new image analysis software package enabling the characterization of steady structures or transitory functional aspects of skin reactions, by highlighting areas in which the echo amplitudes are included within selected values, and by calculating their extension. Three bands were selected as intervals of interest, respectively, highlighting hyporeflecting parts of the dermis, tissue reflecting with intermediate amplitude values and hyperreflecting epidermis and dermis. This method was employed to assess skin thickness, demonstrating its decrease in elderly skin, to characterize and quantify the hypoechogenic subepidermal band appearing in the elderly at volar and dorsal forearm skin, and to evaluate echogenicity of the upper and lower dermis. Our data show that there is a great regional variation in the behaviour of ultrasound reflection of elderly skin in respect to the skin of young subjects. However, a general trend can be identified, consisting in a shift from low-intensity ultrasound echoes, characteristic in the dermis of young subjects, to intermediate or high reflection amplitudes, which are more frequent in elderly skin. Thus, the echographic method provides two parameters for the evaluation of skin aging.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of chronic hypertension on skin blood flow

OBJECTIVE: To determine whether the cutaneous microvasculature of the spontaneously hypertensive rat (SHR) is affected by chronic hypertension. DESIGN: We used laser Doppler techniques to measure skin blood flow in 22 SHR and in 22 non-hypertensive Wistar-Kyoto (WKY) rats over a 1-year time span, beginning at age 3 months. Sites of measurement included the back, leg, and root of the tail, areas with a predominantly nutritive perfusion, and the plantar surface of the paw, which has a large contribution from large arterioles and venules. Flow was measured at basal skin temperature and at the maximally heat-stimulated condition of 44 degrees C. Systolic tail arterial blood pressures were measured concurrently. RESULTS: At baseline, systolic blood pressures were considerably higher in the SHR (190 +/- 4 mmHg) than they were in the WKY rats (138 +/- 2 mmHg). Skin blood flow values at the three nutritive sites were similar in the two species. However, at 44 degrees C, flow was significantly higher at the paw in the SHR (46.8 +/- 3.5 versus 34.3 +/- 2.2 ml/min per 100 g). We attribute this difference to the effect of high perfusion pressure on large arterioles. During the 1-year measurement period, there was no appreciable change in blood flow in the WKY rats. In contrast, the SHR showed a steady progressive decline in skin blood flow at all sites. The largest decline was at the paw with a rate of fall of about 2.4%/month. After 1 year, there was no difference between paw blood flow in the SHR (27.5 +/- 1.8 ml/min per 100 g) and in the WKY rats (27.6 +/- 1.9 ml/min per 100 g). CONCLUSIONS: Skin blood flow reserve falls in response to chronic hypertension. The rate of fall is greater at sites with significant arteriovenous perfusion that at nutritive sites.     

Microbiological evaluation of glycerolized cadaveric donor skin

Record linkage was carried out between the national Registry of AIDS and 13 Cancer Registries (CRs) covering, in 1991, about 15% of the Italian population. Observed and expected numbers of cancers and standardized incidence ratios (SIRs) were assessed in 6067 persons with AIDS, for a total of 25,759 person-years. Significantly increased SIRs were found for Hodgkin's disease [8.9, 95% confidence interval (CI) 4.4-16.0], in which seven of 11 cases were of mixed cellularity type; invasive carcinoma of the cervix uteri (15.5; 95% CI 4.0-40.1); and non-melanomatous skin cancer (3.0, 95% CI 1.3-5.9), in which five of eight cases were basal cell carcinoma. An excess was also seen for brain tumours, but this may be partly due to misdiagnosis of brain non-Hodgkin's lymphoma or other brain diseases occurring near the time of the AIDS diagnosis. The risk for all cancer types, after exclusion of Kaposi's sarcoma (KS) and non-Hodgkin's lymphoma (NHL), was approximately twice the general population risk. An increased SIR for Hodgkin's disease in persons with AIDS is thus confirmed, though it is many times smaller than that for NHL. An association with invasive carcinoma of the cervix is also shown at a population level. The excess of non-melanomatous skin cancer seems to be lower than in transplant recipients.