Arc-scanning very high-frequency digital ultrasound for 3D pachymetric mapping of the corneal epithelium and stroma in laser in situ keratomileusis

PURPOSE: To test and demonstrate measurement precision, imaging resolution, 3D thickness mapping, and clinical utility of a new prototype 3D very high-frequency (VHF) (50 MHz) digital ultrasound scanning system for corneal epithelium, flap, and residual stromal thickness after laser in situ keratomileusis (LASIK). METHODS: VHF ultrasonic 3D data was acquired by arc-motion, meridional scanning within a 10-mm zone. Digital signal processing techniques provided high-resolution B-scan imaging, and I-scan traces for high-precision pachymetry in 4 eyes. Thickness maps of individual corneal layers were constructed. Reproducibility of epithelial, flap, and full corneal pachymetry was assessed for single-point and 3D thickness mapping by repeated measures. Thickness mapping of the epithelium, stroma, flap, and full cornea were determined before and after LASIK. Preoperative to postoperative difference maps for epithelium, flap, and stroma were produced to demonstrate anatomical changes in the thickness profile of each layer. RESULTS: Surface localization precision was 0.87 microm. Central reproducibility for single-point pachymetry of epithelium was 0.61 microm; flap, 1.14 microm; and full cornea, 0.74 microm. Reproducibility for central pachymetry on 3D thickness mapping was 0.5 microm for epithelium and 1.5-microm for full cornea. B-scans and 3D thickness maps after LASIK demonstrated resolution of epithelial, stromal component of the flap, and residual stromal layers. Large epithelial profile changes were demonstrated after LASIK. Topographic variability of flap thickness and residual stromal thickness were significant. CONCLUSIONS: VHF digital ultrasound arc-B scanning provides high-resolution imaging and high-precision three-dimensional thickness mapping of corneal layers, enabling accurate anatomical evaluation of the changes induced in the cornea by LASIK.     

A survey of current physical therapy practices in wound care

Few standardized treatment protocols are available to guide physical therapists through the rapidly changing area of wound care. To assess current physical therapy practices and to determine relationships between specific demographic data and evaluation/intervention techniques utilized in wound care, a questionnaire was developed that used a Likert scale (1 to 5) for responses, offering choices from "always" to "never." The questionnaire was sent to physical therapists at 170 clinical sites used by the University of Mary Program in Physical Therapy in Bismarck, ND. The final return rate was 48.1%. The most commonly used evaluation and intervention techniques were determined. Use of the rubor of dependency test, sharp debridement, enzymatic debridement, compression dressings, and autolytic debridement was found to have a significant (P < .05) relationship to the reported percentage of compromised wound care patients in a clinician's practice; whereas, years of clinician experience has a significant (P < .05) relationship to the use of monofilament testing and the use of electrical stimulation. Reasons for the differences observed, including the role of guidelines, need to be explored.     

Airway hyperresponsiveness to adenosine induced by lipopolysaccharide in Brown Norway rats

We have explored the effects of bacterial endotoxin (lipopolysaccharide; LPS) on the response of the airways of Brown Norway (BN) rats to adenosine. Comparisons have been drawn with the effects on responses to methacholine and 5-hydroxytryptamine. In vehicle-challenged animals, adenosine, given i.v. was only a weak bronchoconstrictor. In contrast, 1 h following intratracheal administration of LPS, 0.3 mg kg-1, bronchoconstrictor responses to adenosine were markedly and selectively enhanced. At this time point, there were no significant changes in leukocyte numbers, eosinophil peroxidase and myeloperoxidase activities or protein concentrations in bronchoalveolar lavage (BAL) fluid. Twenty-four hours after challenge, the sensitivity of the airways to both adenosine and methacholine was reduced relative to the earlier time point and there were substantial increases in each marker of inflammation in BAL fluid. The bronchoconstrictor response to adenosine was blocked selectively by methysergide, disodium cromoglycate and the broad-spectrum adenosine receptor antagonist, 8-SPT, but not by DPCPX or ZM 243185, selective antagonists for the A1 and A2A receptors, respectively. Thus, the response to adenosine augmented following LPS is mast cell mediated and involves a receptor which can be blocked by 8-SPT but not by selective A1 or A2A receptor antagonists. It thus bears similarity to the augmented response to adenosine induced by allergen challenge in actively sensitized BN rats. Exposure to LPS could be a factor along with allergen in determining the increased sensitivity of the airways of asthmatics to adenosine.     

A review of epidemiologic studies on aluminum and silica in relation to Alzheimer's disease and associated disorders

Although the neurotoxicity of aluminum is well established, the association between the metal and dementia or associated disorders remains a subject of debate. In this article, we present a review of articles published on epidemiologic studies of this subject. Different sources of exposure are considered (occupational exposure, aluminum-containing products), with emphasis on drinking water. We separate the various health effects of aluminum into three categories: neurological disorders (other than cognitive decline or AD); cognitive decline; and dementia or Alzheimer's disease. Furthermore, we present the results obtained on silicon in drinking water, a chemical constituent that interacts with aluminum. We conclude that not enough epidemiological evidence supports a link between aluminum in drinking water and AD. The role of silica in drinking water has been less studied, and clear results have not yet emerged.     

Diet, length of gestation, and fecal short chain fatty acids in healthy premature neonates

BACKGROUND: Excretion of fecal short-chain fatty acids (SCFAs) may indicate changes in colonic or colonocyte metabolism. The aim of this study was to detect the influence of gestational age and feeding practices on SCFA concentrations and profiles in healthy preterm infants. METHODS: A total of 198 fecal samples (28 infants) were collected from 8 to 21 days of age from 3 groups of preterm infants born at 33 to 37 weeks of gestation and fed either breast milk (group I) or Nutramigen, a lactose-free formula (group II), and extremely preterm infants born before 33 weeks of gestation and fed breast milk (group III). Total SCFA concentrations and SCFA profiles were analyzed using a gas chromographic (GC) procedure. RESULTS: Total fecal SCFA excretion did not differ significantly between group I (mean, 24.0 micromol/g; range, 1.3 to 118.8 micromol/g) and group II (mean, 23.0 micromol/g; range, 3.0 to 73.3 micromol/g). Conversely, differences occurred between SCFA profiles and became significant after day 17. The main differences were a significant increase in the butyric acid concentration (12% versus 30%) with group II. Compared with group I, fecal SCFA concentrations were 3.2-fold lower (7.4 micromol/g; range, 0.3 to 37.4 micromol/g) in group III with no significant changes in the profiles. CONCLUSIONS: Fecal SCFA excretion may vary in absence of any digestive disease. During this study, in terms of gestational age, total SCFA concentrations were significantly lower in extremely premature infants compared with infants born less premature, despite their known higher deficiency in intestinal lactase activity. In terms of diet, the absence of lactose did not lead to a decrease in colonic fermentation and induced changes in SCFA patterns. These new baseline data may offer clues to further development of milk formulas.     

Evaluating end-of-life care from the perspective of the patient's family

This article is written from personal experiences with the recent death of the authors' mother. It highlights the problems the authors encountered, while acknowledging the positive aspects of treatment during a difficult time. The overall purpose is to improve end-of-life care by advancing policy through research, legislation, and education. The impetus for writing this article is personal experience, but its larger purpose is to address issues that many readers will face in the future and suggest possible reforms, especially in the area of education.     

Frequent detection of human papillomavirus 16 E2-specific T-helper immunity in healthy subjects.

The incidence of genital human papillomavirus (HPV) infections is high in young, sexually active individuals. Most infections are cleared within 1 year after infection. The targets for the cellular immune response in this process of viral clearance remain to be identified, but the expression pattern of the E2 protein in early infection and low-grade cervical intraepithelial neoplasia renders this early protein a candidate antigen. Therefore, we studied the HPV16 E2-specific T-cell responses in more detail. Very strong proliferative responses against one or more peptide-epitopes derived from this antigen can be found in peripheral blood mononuclear cell cultures of approximately half of the healthy donors. Additional analysis revealed that at least a majority of these responses represent reactivity by memory CD4(+) T-helper (Th) 1-type cells capable of secreting IFN-gamma on antigenic stimulation. Interestingly, all of the E2 peptides against which strong responses were detected are clustered in the key functional domains of the E2 protein, which are conserved to considerable extent between HPV types. This suggests that HPV16 E2-specific Th memory may be installed through encounter with HPV types other than HPV16. Indeed, one HPV16 E2-specific Th clone was found to cross-react against homologuous peptides from other HPV types, but three other Th clones failed to show similar cross-reactivity. Therefore, part of the HPV16 E2-specific Th memory may relate to previous encounter of other HPV types, whereas the majority of the immune repertoire concerned is most likely established through infection with HPV16 itself. Our data are the first to reveal that the T-cell repertoire of healthy donors can contain particularly high frequencies of E2-specific memory Th cells and suggest that boosting of this immunity can be used for preventive and therapeutic vaccination against HPV-induced lesions.     

A new simplified method of gene typing

Abstract: SSP-PCR (sequence-specific primer) DNA typing was performed in Terasaki trays using 1.5 μ1 of DNA, and the ethidium-stained PCR product was measured by direct fluorometric reading. Elimination of the gel electrophoresis step greatly simplified the SSP method. 17 serological DR specificities were discriminated for 239 DNA samples utilizing the new method, standard SSP, sequence-specific oligonucleotide probe (SSOP), and restriction fragment length polymorphism (PCR-RFLP). Results showed 98% concordance between the SSP-PCR assay and conventional methods. DRB1 alleles were determined by PCR-RFLP in 59 samples, by SSP in 110 samples, and by consensus (all methods) in the remaining samples.     

Production of tumor necrosis factor by rat mesangial cells in response to bacterial lipopolysaccharide

Tumor necrosis factor (TNF) is a cytokine which is produced by mononuclear phagocytes upon activation by bacterial lipopolysaccharide (LPS) and various other stimuli. In immune-mediated glomerulonephritis, infiltration of glomeruli by monocytes-macrophages is associated with production of TNF. The purpose of the present experiments was to determine whether mesangial cells could also contribute to glomerular TNF synthesis. TNF activity has been determined in the culture medium of rat mesangial cells using a L-929 fibroblast lytic assay. This activity was detectable only when the cells were exposed to LPS (0.1 to 10 micrograms/ml) and for periods longer than one hour. The cytotoxic factor was identified as TNF since: (1) the lytic activity was completely inhibited by an anti-mouse TNF polyclonal antibody and was associated with suppression of lipoprotein lipase activity in adipocytes; (2) its molecular weight (110,000 daltons) corresponded to that observed for murine TNF under non-denaturing conditions; and (3) mRNA encoding TNF was expressed by mesangial cells two hours after addition of LPS. To assess the mechanisms whereby TNF production was regulated, the role of prostaglandin E2 (PGE2) was determined. LPS caused a dose-dependent increase of PGE2 synthesis by mesangial cells. Treatment by indomethacin promoted a suppression of PGE2 production together with an increase of TNF synthesis, indicating that PGE2 acted in a negative feedback manner to regulate the production of TNF. Addition of PGE2 (0.1 to 300 nM) or 8-bromo cyclic AMP (0.1 to 100 microM) induced similar dose-dependent reductions of TNF synthesis. Thus the inhibitory effect of PGE2 probably required in part cyclic AMP accumulation.(ABSTRACT TRUNCATED AT 250 WORDS)