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Biomedical subjects

K F Ross

Publications and source records attributed to K F Ross.

13 recordsLinked to original sources
PubMed2001

Accidental sharp force injury fatalities.

The authors review all accidental sharp force injury deaths investigated at the Southwestern Institute of Forensic Sciences from 1990 to 1999. Twenty-two cases of accidental sharp force injury were identified, accounting for 0.29% of all accidental deaths (9,562) during the 10-year study period. Included in this series are 5 incised wounds, 11 stab wounds, 4 chop wounds, and 2 deaths caused by dog attacks. About half of the cases involved some type of motorized machinery. The victims' ages ranged from 2 years to 71 years, with most deaths occurring in older teenagers and younger adults. Male subjects (17) were involved much more frequently than female subjects (5). In 50% of the cases, ethanol or other drug use was a possible underlying contributing factor in the accident. The cases are briefly reviewed, and the importance of detailed investigation in manner-of-death certification is emphasized.

Accidents↗
PubMed2001

Calprotectin expression by gingival epithelial cells.

Calprotectin, a heterodimer of MRP8 and MRP14 with antimicrobial properties, is found in the cytosol of neutrophils, monocytes, and human gingival keratinocytes. During inflammation of the oral mucosa, the expression of immunoreactive calprotectin appears upregulated. Given the possible cell sources, we sought to learn if epithelial cells upregulate calprotectin in response to proinflammmatory agents. First, human gingival keratinocytes were maintained in primary culture until senescence. At each passage, cells were harvested and analyzed for quantitative expression of MRP8 and MRP14 subunit mRNA by RNase protection assays and calprotectin complex by enzyme-linked immunosorbent assay. Calprotectin expression was constitutive in the primary gingival keratinocytes, but calprotectin-specific mRNA and protein tended to increase as the cells neared senescence. To test whether calprotectin expression was inducible, immortalized gingival keratinocyte cultures were treated for 2 to 4 h with lipopolysaccharide (LPS) or interleukin-1 beta (IL-1 beta). As a positive control for inducible expression, immortalized keratinocytes were incubated with phorbol myristate acetate (PMA) (50 ng/ml) for 24 h. Incubation with PMA stimulated increased expression of MRP8 and MRP14 mRNA within 2 h, peaking within 5 h. MRP8- and MRP14-specific mRNA expression by immortalized keratinocytes appeared to be unaffected by LPS or IL-1 beta. In contrast, LPS, IL-1 beta, and PMA each upregulated IL-8. These data show that calprotectin mRNA is expressed constitutively in cultured keratinocytes, while expression by immortalized cells appears to be independent of the exogenous proinflammatory agents LPS and IL-1 beta.

Antigens, Differentiation↗
PubMed2001

Calprotectin expression inhibits bacterial binding to mucosal epithelial cells.

Squamous mucosal epithelial cells constitutively express calprotectin in the cytoplasm. To study how this antimicrobial protein complex confers epithelial resistance to invading bacteria, an epithelial cell line was stably transfected to express the calprotectin complex. Cells expressing calprotectin resist invasion by Listeria monocytogenes and Salmonella enterica serovar Typhimurium. Calprotectin expression was accompanied by altered actin organization, increased alpha3 integrin expression, and spreading cell morphology. In this study, we assessed whether calprotectin expression affects bacterial binding and uptake. Threefold-fewer Listeria organisms bound to the surfaces of calprotectin-expressing cells, and 10-fold fewer were localized intracellularly by immunofluorescence. Similarly, fewer Salmonella organisms bound to cells expressing calprotectin. Calprotectin-expressing and sham-transfected cells showed similar levels of expression of surface E-cadherin and intracellular adhesion molecule 1 (ICAM-1) by flow cytometry. Calprotectin-expressing transfectants expressed calprotectin on the cell surface as well as in the cytosol. In conclusion, two bacterial pathogens showed reduced binding to calprotectin-expressing epithelial cells. Calprotectin-expressing cells appeared to have internalized disproportionately fewer Listeria organisms, suggesting that reduced binding and translocation supplemented direct antimicrobial effects in calprotectin-expressing cells.

Bacterial Adhesion↗
PubMed2001

Calprotectin expression in vitro by oral epithelial cells confers resistance to infection by Porphyromonas gingivalis.

Calprotectin, an S100 calcium-binding protein with broad-spectrum antimicrobial activity in vitro, is expressed in neutrophils, monocytes, and gingival keratinocytes. In periodontitis, calprotectin appears upregulated and is detected at higher levels in gingival crevicular fluid and tissue specimens. How calprotectin contributes to the pathogenesis of periodontal diseases is unknown. To isolate the effects of calprotectin, a calprotectin-negative oral epithelial cell line was transfected with calprotectin genes to enable expression. Porphyromonas gingivalis was permitted to bind and invade transfected cells expressing calprotectin and sham transfectants. Rates of invasion into both cell lines were compared using the antibiotic protection assay. Transfected cells expressing calprotectin showed 40 to 50% fewer internalized P. gingivalis than sham transfectants. Similarly, binding to calprotectin expressing cells was reduced approximately twofold at all time points (15, 30, 45, and 60 min) as estimated by immunofluorescence analysis. Independent of invasion, however, prolonged exposure to P. gingivalis induced epithelial cell rounding and detachment from the substratum. These morphological changes were delayed, however, in cells expressing calprotectin. Using P. gingivalis protease-deficient mutants, we found that Arg-gingipain and Lys-gingipain contributed to epithelial cell rounding and detachment. In conclusion, expression of calprotectin appears to protect epithelial cells in culture against binding and invasion by P. gingivalis. In addition, cells expressing calprotectin are more resistant to detachment mediated by Arg-gingipain and Lys-gingipain. In periodontal disease, calprotectin may augment both the barrier protection and innate immune functions of the gingival epithelium to promote resistance to P. gingivalis infection.

Adhesins, Bacterial↗
PubMed1999

Human herpesvirus-6 and sudden death in infancy: report of a case and review of the literature.

Investigation of sudden death in infancy is a vital function of the medical examiner's office. Surveillance of these cases may lead to recognition of new diseases or new manifestations of previously described diseases. Human herpesvirus-6 (HHV-6) is a relatively newly described virus that has been recognized as a cause of acute febrile illness in early childhood. While most cases are apparently self-limited, seven fatal cases have been reported. We present a case of a seven-month-old Latin American male with recent otitis media and vomiting who was found dead in bed. Autopsy revealed interstitial pneumonitis with an atypical polymorphous lymphocytic infiltrate in the liver, kidney, heart, spleen, lymph nodes, and bone marrow, associated with erythrophagocytosis. Polymerase chain reaction (PCR) analysis of formalin-fixed paraffin-embedded tissue was positive for HHV-6 and negative for Epstein-Barr virus (EBV) and cytomegalovirus (CMV). HHV-6 was also detected in the atypical lymphoid infiltrate by in-situ hybridization.

Child, Preschool↗
PubMed1998

Immersion technique for brain removal in perinatal autopsies.

Perinatal autopsies present forensic patholgists with a variety of challenges, not the least of which involves the removal and examination of very small and sometimes fragile organs. Removal of the immature brain can be particularly troublesome. Even if great care is taken during brain removal, one is often left with no more than a semifluid amorphous mass of softened tissue by the time the brain is ready to be fixed in formalin. We describe a method of perinatal brain removal which helps to preserve brain shape and integrity. By removing the brain while the head (and body) is totally immersed in water, we find that the brain is easier to remove and less apt to destruction. Subsequent fixation in formalin results in well-preserved, intact specimens, allowing for optimal examination and sectioning.

Autopsy↗
PubMed1993

Isolation and characterization of the lantibiotic salivaricin A and its structural gene salA from Streptococcus salivarius 20P3.

A bacteriocin-like inhibitory substance, salivaricin A, was purified from cultures of Streptococcus salivarius 20P3 and was shown by ion spray mass spectrometry to have a molecular mass of 2,315 +/- 1.1 Da. Amino acid composition analysis demonstrated the presence of lanthionine, indicating that salivaricin A may be a member of the lantibiotic class of antibiotic substances. The sequence of eight amino acids at the N terminus of the molecule was determined by Edman degradation, and mixed oligonucleotide probes based on part of this sequence (GSGWIA) were used to detect the salivaricin A structural gene. A 6.2-kb EcoRI fragment of chromosomal DNA from strain 20P3 that hybridized with the probes was cloned, and the hybridizing region was further localized to a 379-bp DraI-AluI fragment. Analysis of the nucleotide sequence of this fragment indicated that salivaricin A is synthesized as a 51-amino-acid prepeptide that is posttranslationally modified and cleaved to give a biologically active 22-residue peptide containing one lanthionine and two beta-methyllanthionine residues. The secondary structure of presalivaricin A was predicted to be similar to that of type A lantibiotics, with a hydrophilic alpha-helical leader sequence and a propeptide region with potential for beta-turn formation and a lack of alpha-helicity. The sequence around the cleavage site of presalivaricin A differed from that of other type A lantibiotics but was similar to that of several bacteriocin-like inhibitory substances produced by lactic acid bacteria.

Alanine↗
PubMed1982

Water in malignant tissue, measured by cell refractometry and nuclear magnetic resonance.

It has been known that tumour-bearing tissues often have a significantly higher water content than the normal tissues from which they have been derived. Most of the evidence suggesting this in recent years has been obtained from methods employing nuclear magnetic resonance (NMR), which, although undoubtedly indicative of hydration, cannot at present be precisely quantified. Furthermore it has not been possible by these means to determine whether this overall increase in the water content of the tissue is principally an increase in the extracellular fluid or whether the water content of the tumor cells and the cells immediately adjacent to the tumours increases also. In this investigation, which is the first of its kind, a combination of NMR and immersion refractometry techniques have been used to examine the water content of normal and tumour bearing tissues. NMR measurements were made on pieces of normal and tumour bearing tissue from rat livers: intact living cells were also isolated from these pieces and their refractive indices measured by immersion refractometry from which the water content of their cytoplasm was calculated. It was found that all the cells so measured obtained from hepatomas had more water in their cytoplasm (usually over 5% more water) than any of the cells from normal livers; and that normal-looking liver cells taken from the vicinity of hepatomas also all had more water in them than those of normal liver cells, although the differences in this case were less. These results were closely parallel to those obtained by NMR measurements. It is therefore concluded that an appreciable proportion of the increase in the water content of the tissue as a whole that occurs during carcinogenesis, must, in this tissue, be an increase in intracellular water.

Animals↗
PubMedDate not supplied

Fatal hepatic short-chain L-3-hydroxyacyl-coenzyme A dehydrogenase deficiency: clinical, biochemical, and pathological studies on three subjects with this recently identified disorder of mitochondrial beta-oxidation.

This report describes the clinical, biochemical, and pathological findings in three infants with hepatic short-chain L-3-hydroxyacyl-coenzyme A dehydrogenase (SCHAD) deficiency, a recently recognized disorder of the mitochondrial oxidation of straight-chain fatty acids. Candidate subjects were identified from an ongoing study of infant deaths. SCHAD analysis was performed on previously frozen liver and skeletal muscle on subjects with a characteristic urine organic acid profile. Autopsy findings were correlated with the biochemical abnormalities. Enzyme analysis in liver revealed marked deficiency in SCHAD with residual activities of 3-11%. All subjects had normal activity in skeletal muscle. However, Western blot analysis of SCHAD revealed an identical truncated protein in both liver and muscle from one patient, suggesting that SCHAD is similar in liver and muscle and that the normal activity in muscle may be due to other enzymes with C4 activity. Autopsy findings revealed marked steatosis and a muscle pattern consistent with spinal muscular atrophy in one patient. Lipid storage was less pronounced in one patient and not detected in the third patient who had a well-documented history of recurrent hypoglycemia. This is the initial pathological characterization of this enzyme defect, and our observations suggest that SCHAD deficiency is a very severe disorder contributing to early infant death.

3-Hydroxyacyl CoA Dehydrogenases↗