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Biomedical subjects

P W Soballe

Publications and source records attributed to P W Soballe.

12 recordsLinked to original sources
PubMed1998

Electric cautery lowers the contamination threshold for infection of laparotomies.

BACKGROUND: Interplay between wound resistance factors and bacterial innoculum determines the risk of surgical infection. Since cautery causes more damage than the scalpel, our hypothesis is that lower numbers of bacteria are required to infect wounds made by electric cautery than to infect wounds made with a scalpel. METHODS: Abdominal fascia was incised in 375 rats by cold knife, cutting current, or coagulation current. Wounds were innoculated with increasing numbers of bacteria and histologically scored at 7 days for necrosis, inflammation, and abscess. RESULTS: Coagulation current causes more inflammation, necrosis, and abscesses than the scalpel at all bacterial levels. Electric cutting current is intermediate, causing more damage than the scalpel only after contamination reached 10(5). Above this threshold most wounds were infected in all groups. CONCLUSIONS: Electric coagulation current should be used only when the need for meticulous hemostasis outweighs the considerably increased risk of infection. Electric cutting current is less destructive but also less hemostatic; indications for its use are difficult to identify.

Animals↗
PubMed1998

UVB induces atypical melanocytic lesions and melanoma in human skin.

A direct causal relationship between ultraviolet (UV) light in the B range and melanoma development has not been demonstrated in humans; this study aims to establish causality. A total of 158 RAG-1 mice, grafted with human newborn foreskin, were separated into four groups and observed for a median of 10 months: 1) no treatment, 2) a single treatment with 7,12-dimethyl(a)benzanthracene (DMBA), 3) UVB irradiation at 500 J/m2 alone, three times weekly, and 4) a combination of DMBA and UVB. Twenty-three percent of 40 normal human skin grafts treated with UVB only and 38% of 48 grafts treated with the combination of DMBA and UVB developed solar lentigines within 5 to 10 months of treatment. Melanocytic hyperplasia was found in 73% of all UVB-treated xenografts. Histological melanocytic changes resembling lentigo and lentigo maligna were seen in several skin grafts treated with both DMBA and UVB. In one graft of an animal treated with a combination of DMBA and UVB, a human malignant melanoma, nodular type, developed. This experimental system demonstrates that chronic UVB irradiation with or without an initiating carcinogen can induce human melanocytic lesions, including melanoma.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1997

Mutations in beta-catenin are uncommon in colorectal cancer occurring in occasional replication error-positive tumors.

Beta-catenin has been identified as an oncogene in colon cancer and melanoma. Phosphorylation of sites in exon 3 of beta-catenin leads to degradation of this protein. These sites are primary targets for activating mutations. The frequency with which oncogenic mutations at these sites are found in colorectal cancer is unknown, as is the frequency of their occurrence in other malignancies. We analyzed 92 colorectal cancers (CRCs) and 57 cancer cell lines (representing a diversity of tumor types) to determine the frequency of activating mutations in this gene. Mutations in exon 3 of beta-catenin were found in 2 of 92 CRCs and in the colorectal cancer cell line HCT 116. Both tumors with beta-catenin mutations exhibited widespread microsatellite instability, which is indicative of a replication error phenotype, a phenotype known to be present in HCT 116. This suggests that mutations in beta-catenin are infrequent in CRC and miscellaneous cancer cell lines and may occur in association with a replication error phenotype.

Adult↗
PubMed1997

Adenovirus infection enhances killing of melanoma cells by a mitotoxin.

Toxins are effective in cell killing if internalized efficiently. Conjugation of the plant toxin saporin with basic fibroblast growth factor has increased tumor killing due to better internalization, but toxin uptake by cells has remained relatively inefficient. We show here that infection of melanoma cells with a replication-defective adenovirus enhances cell killing by the mitotoxin basic fibroblast growth factor-saporin more than 10-fold, thus allowing tumor cell killing in vivo at nontoxic concentrations. Adenovirus infection leads to increased apoptosis by the mitotoxin due to enhanced internalization of the ligand-receptor complex and release of the active toxin from the endosomes.

Adenoviridae↗
PubMed1997

UVB induction of epithelial tumors in human skin using a RAG-1 mouse xenograft model.

To examine the effects of chronic ultraviolet light on human epidermal cells, we grafted white human skin onto recombinase activating gene-1 knockout mice. We found previously that the maximal concentration of ultraviolet B radiation (290-320 nm) tolerated by human skin xenografts was 500 J per m2 when given three times weekly. One hundred and fifty-eight grafted mice were randomized and observed for a median of 10 mo in four groups: (i) no treatment; (ii) one treatment with the chemical carcinogen dimethyl-(a)benzanthracene; (iii) ultraviolet B three times weekly; and (iv) a combination of dimethyl-(a)benzanthracene and ultraviolet B. Approximately half of the skin specimens treated with ultraviolet B developed superficial milia and epidermal cysts. Grafts contained up to seven milia lesions between 4 and 8 mo after initiation of treatment, whereas the number of larger epidermal cysts was rarely more than two. Milia and cysts developed in the skin regardless of pigmentation or tanning. Actinic keratoses arose in 9% of grafts treated with ultraviolet B alone and in 19% of grafts treated with the combination of dimethyl-(a)benzanthracene and ultraviolet B. Invasive squamous cell carcinomas developed in 10% of grafts after combined dimethyl-(a)benzanthracene and ultraviolet B treatment and lesions were restricted to skin grafts that did not tan. These findings demonstrate that (i) development of ultraviolet-induced lesions can be experimentally accelerated in human skin, (ii) xenografted recombinase activating gene-1 deficient mice are superior to severe combined immunodeficiency disease mice for chronic ultraviolet B studies, and (iii) benign cystic tumors and squamous cell carcinomas are caused by ultraviolet B.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1996

Carcinogenesis in human skin grafted to SCID mice.

To directly examine a multistage carcinogenesis model and the role of UV light in human tissues, we grafted human skin onto mice with severe combined immunodeficiency disease. We found that the maximum dose of UV radiation in the B range (UVB; 280-320 nm) tolerated by these grafts was 500 J/m2 three times weekly. One hundred fifty-one grafted mice were then randomized and observed for a median of 9 months in five groups: no treatment, chemical initiation alone, UVB as a complete carcinogen, initiation plus UVB promotion, and initiation plus UVB and phorbol ester promotion. Actinic damage and squamous atypia were found in grafts of all groups receiving UV treatment; unequivocal human squamous carcinomas developed in two of these. Species origin was verified by human-specific bisbenzimide staining and in situ hybridization for human-specific Alu segment. Overall basal proliferation, measured immunohistologically, was reduced in UV-treated grafts, but foci of hyperproliferation were seen in conjunction with the dedifferentiated expression of cytokeratins 1, 10 and 5, 8. Murine tumors also developed frequently, confirming the biological relevance of the carcinogenic strategies tested. These findings demonstrate that development of malignant human tumors can be experimentally accelerated in human tissue.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1995

Experimental local therapy of human melanoma with lytic magainin peptides.

Magainin peptides and model amphipathic peptides exhibit antibiotic activity and are also cytolytic for transformed human cells. Here we demonstrate in vitro that MSI-511 (an all-D amino-acid model magainin peptide) and MSI-130 (a margainin analogue) were more lytic for 17 human melanomas than for normal melanocytes. Melanomas established s.c. in athymic nude mice and then injected once with the peptide MSI-511 completely disappeared in 6 out of 9 animals, whereas a control peptide had no effect. Murine skin at the tumor injection site was initially affected, but healed within 2 weeks with minimal scarring. Similarly, accelerated healing was seen in human skin grafted to SCID mice and injected with MSI-511. Our results indicate that lytic magainin peptides can be used for local tumor therapy with minimal long-term damage to normal tissues.

Animals↗
PubMed1994

Cellular pathways leading to melanoma differentiation: therapeutic implications.

The induction of differentiation, as evidenced by benign growth characteristics, dendritic morphology, pigmentation capability, and a mature antigenic phenotype, is an attractive theoretical basis for therapy in human melanoma. Melanoma differentiation can be experimentally induced by modulating intracellular pathways involving protein kinase C, tyrosine kinases, and protein kinase A, or by modulating nuclear transcription with retinoids, DNA-damaging agents, and chemotherapeutic drugs. Other experimental differentiating agents include the amino acid tyrosine, histamine receptor antagonists, polyamine antagonists, dimethylsulphoxide, caffeic acid ester, and butyrate. The mechanisms involved in the actions of many of these agents are beginning to be understood and the pathways are often intersecting; cross-talk in the form of negative and positive feedback loops is extensive. Uncoupling of pathways is also seen, with some agents leading to simultaneous increases in both differentiated and transformed characteristics. While clinical benefits of this approach have so far been sparse, greater understanding of the cellular pathways of differentiation may open new therapeutic options in melanoma.

Cell Transformation, Neoplastic↗
PubMed1991

Cholecystokinin enhanced hepatobiliary scanning with ejection fraction calculation as an indicator of disease of the gallbladder.

Chronic acalculous cholecystitis represents 5 to 20 per cent of electively treated diseases of the gallbladder. A 70 per cent success rate in relieving these patients of chronic pain was reported when surgical treatment was recommended based on symptoms alone. The cholecystokinin ejection fraction, which is a quantitative measure of emptying of the gallbladder, was 95 per cent accurate in predicting which patients would be relieved of symptoms by surgical treatment. In this study, we report our consecutive experience during a 20 month period with 83 patients.

Adult↗
PubMed1989

Preoperative whole-gut lavage vs. traditional three-day bowel preparation in left colon surgery.

Isotonic, isosmotic lavage is a safe and effective means of mechanical preparation of the large bowel for left colon surgery. In this prospective, randomized trial comparing lavage with a more traditional three-day bowel preparation, the lavage was well tolerated, led to decreased preoperative hospital days, and produced no higher incidence of infectious complications when compared to the traditional three-day technique.

Anti-Bacterial Agents↗
PubMed1984

Peritoneal lavage in blunt abdominal trauma.

Peritoneal lavage is a safe and relatively simple procedure that can eliminate delay in diagnosing significant intra-abdominal injury after blunt abdominal trauma. Serious complications from the procedure are quite uncommon. The use of an "open" technique minimizes the risk of false-positive results. The technique does not uncover retroperitoneal injuries.

Abdominal Injuries↗