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Biomedical subjects

A M Davidoff

Publications and source records attributed to A M Davidoff.

At least 37 records · Page 2Linked to original sources
PubMed1996

Management of the gastrointestinal tract and nutrition in patients with cloacal exstrophy.

Cloacal exstrophy is a rare condition in which there is a complex set of congenital anomalies that affect multiple-organ systems, including the gastrointestinal tract. Twenty-six patients with cloacal exstrophy have been treated at the authors' institution during the last 20 years. Gastrointestinal features usually included omphalocele, exstrophy of an everted cecal plate, a short blind-ending distal colon, imperforate anus, and, occasionally, a shortened small bowel. Additional gastrointestinal anomalies included four cases of colonic duplication, one duodenal web, and one malrotation. The average time until the initiation of enteral feeding after initial surgery was 15.6 days, and the time until discontinuation of total parenteral nutrition (TPN) was 36 days. One patient with short bowel syndrome died of TPN-associated liver failure. Five other patients exhibited short bowel physiology, but ultimately each was weaned from supplemental intravenous hyperalimentation. Four patients have undergone posterior sagittal anorectoplasty, and one has had perineal anoplasty. Of these patients, two are continent and one is free of soilage on a bowel management program. In the authors' experience with management of the gastrointestinal tract and nutrition in patients born with cloacal exstrophy, many patients initially exhibited short bowel physiology, although most eventually adapted. However, very few patients have been able to achieve bowel control.

Abnormalities, Multiple↗
PubMed1996

Thoracoscopic management of empyema in children.

The appropriate management of empyema in children is controversial. Traditional surgical approaches have included thoracotomy and open drainage, decortication, and thoracoplasty. While generally effective, these procedures can be associated with considerable morbidity. We have sought to assess the utility of video-assisted thoracoscopic adhesiolysis and pleural debridement for the treatment of empyema in children. Nine children with postpneumonic empyema unsuccessfully managed with a single attempt at closed tube thoracostomy underwent thoracoscopic drainage during the past 2 years. The empyema was successfully treated with this technique in seven patients with no further interventions being required. Procedures performed early in the fibrinopurulent stage were technically easier. The average time before chest tube removal was 8.5 days. An immunocompromised patient required a subsequent open decortication and a patient with a coagulopathy required two subsequent open procedures for drainage of a recurrent hemothorax. We conclude from this experience that video-assisted thoracoscopic adhesiolysis and pleural debridement can be successfully performed in children. Benefits include good visualization of the entire thoracic cavity for more effective debridement and efficient drainage, and subjectively diminished postoperative pain and associated morbidity.

Adolescent↗
PubMed1996

Intestinal perforation due to an ingested foreign body: laparoscopic management.

The authors report the case of a previously healthy 10-year-old boy who accidentally ingested a toothpick. He presented to the hospital 7 days after the incident with left lower quadrant abdominal pain and fever; there was evidence of localized peritoneal irritation by exam. He had mild leukocytosis. An abdominal CT scan showed the toothpick in the sigmoid colon with extension through the bowel wall. Laparoscopic exploration was undertaken and an 8-cm toothpick was identified and removed from the perforation site in the sigmoid colon. Via a small suprapubic incision the sigmoid was delivered and repaired. The patient had an uneventful recovery and was discharged home 2 days after the procedure.Laparoscopic exploration can be diagnostic and therapeutic in the management of ingested foreign bodies with suspected intestinal perforation.

Child↗
PubMed1996

Laparoscopic oophorectomy in children.

Laparoscopy is a well-established diagnostic and therapeutic modality for adult gynecologic surgery. We have sought to assess the feasibility of the laparoscopic approach to a particular gynecologic procedure, oophorectomy, in the pediatric population. Five patients under-went laparoscopic oophorectomy during the past year. The indication for oophorectomy in three cases was ovarian torsion---one in association with a hemorrhagic cyst another with a benign teratoma, and one that occurred prenatally. The fourth patient had a teratoma with significant solid component and the final patient was a young with Turner's syndrome who had laparoscopic exploration and removal of bilateral streak ovaries. Oophorectomy was successfully completed laparoscopically in each patient. In two cases a trocar site had to be widened to remove the specimen from the abdominal cavity. Post operative recovery was prompt, with time to discharge being an average of 2 days. From this experience we conclude that laparoscopic oophorectomy can be successfully accomplished in infants and children. It is technically an easy procedure and has the benefits of excellent visualization of the entire lower abdomen and pelvis including the contralateral ovary, rapid postoperative recovery, and good cosmetic result.

Adolescent↗
PubMed1995

The role of surgery in the management of stage IV neuroblastoma: a single institution study.

The role of surgery in the management of Stage IV neuroblastoma is still far from clear. Seventy-nine patients with this diagnosis presented to the Children's Hospital of Philadelphia during the 10-year period, 1977 to 1986. Four-year survival was 23%. A major resection of the primary tumor was undertaken in 54 patients. The timing of the procedure (at presentation or delayed) had no effect on survival. The patients were divided into three groups based on the extent of surgical resection: Group 1, no surgery or biopsy only (25); Group 2, complete gross resection (34); Group 3, incomplete resection with residual gross disease (20). Four-year survival was 16, 15, and 45%, respectively. The patients were then classified as favorable or unfavorable, on the basis of biological prognostic factors at presentation. When this analysis was combined with the extent of surgery it was discovered that Group 3 contained a higher proportion of favorable patients, accounting for the better survival. Within each group survival correlated with the expected prognosis. The outcome for a patient with Stage IV neuroblastoma depends on the biological characteristics of the tumor, and there is currently no evidence that these can be favorably altered by the timing or extent of surgical resection. Defining the appropriate role of surgery in the management of these patients will require a prospective randomized study which takes into account the inherent biological variability of the disease.

Adolescent↗
PubMed1994

Malignant melanoma in children.

BACKGROUND: Cutaneous melanoma is an uncommon malignancy in children and for this reason, there is little information available regarding the timing and patterns of recurrence in children with this disease. This study reviews the experience at a single institution (Duke University Melanoma Clinic) in treating children with malignant melanoma. METHODS: Eighty-five patients < or = 18 years of age with malignant melanoma have been treated. All but three patients were over the age of 10; 73% of them were > 14. As for adults, treatment consisted of wide local excision of all primary lesions with primary closure or split-thickness skin graft, as needed. In addition, 22 patients underwent dissection of regional lymph nodes. Patients whose tumors had aggressive pathologic characteristics were treated with an adjuvant immunotherapy protocol. Patients with recurrence at distant sites were offered combination chemotherapy. RESULTS: Patients and pathologic characteristics of sex, race, primary site, histologic type, tumor thickness, and Clark level were similar to those observed in adults. Actuarial survival rates (79% versus 77% at 5 years) of the pediatric and adult Stage I melanoma patients were also not significantly different. Children had a greater incidence of recurrence after initial treatment, although recurrence tended to happen after a longer disease-free interval than for adults. Half of the 79 children who were first seen with Stage I disease have suffered a relapse, but more than one-third were disease free for > or = 5 years after initial treatment. Of the 18 patients who were disease free for > or = 7 years, 12 (67%) ultimately had recurrent disease, including five patients who had recurrences > 13 years after initial diagnosis. CONCLUSIONS: The early age at which malignant melanoma may occur and the significant potential for very late recurrence mandate that pediatricians and other primary care physicians consider the diagnosis of melanoma even in young patients with new skin lesions and that patients treated for melanoma be carefully followed for a lifetime.

Adolescent↗
PubMed1993

Spectrum of mutation and frequency of allelic deletion of the p53 gene in ovarian cancer.

BACKGROUND: The p53 gene encodes a nuclear phosphoprotein present in low levels in normal human cells. The wild-type form of this protein functions to restrain inappropriate cellular proliferation. Approximately one half of human epithelial ovarian cancers have mutations in the p53 gene and overexpress the mutant protein product. Deletion of one allele of the p53 gene also frequently occurs in these cancers. PURPOSE: We sought to define the spectrum of mutations in the p53 gene in epithelial ovarian cancer with respect to both the specific codons involved and the type of mutations observed. We also examined the frequency of allelic deletion of the p53 gene in cancers containing p53 gene mutations. METHODS: Tissue samples from the epithelial ovarian cancers of 62 patients were obtained during initial laparotomy. Histologic examination was done to ensure that the experimental samples used in this study contained more than 75% cancer cells. Total RNA was extracted from these samples and separately from matched control noncancerous regions of the surgical specimen or white blood cells. The purified RNAs were reverse transcribed to generate cDNA copies of exons 4-10 of the p53 gene. Two rounds of polymerase chain reaction (PCR) were conducted to produce enough template for DNA sequence analysis of the regions of interest within the p53 gene. Dideoxy sequencing of at least two independent productions of each amplified DNA template was done to confirm the validity of the mutations found. Allelic deletions were identified by PCR and gel electrophoretic techniques to examine three polymorphisms within the p53 gene in cancer-normal DNA pairs. RESULTS: We identified 45 mutations in exons 5-8 of the p53 gene, where mutations frequently have been found in other cancer types. An additional mutation was identified in exon 4. Overall, 72% of the mutations were transitions, 24% transversions, and 4% microdeletions. Allelic deletion of the other p53 allele was seen in 67% of ovarian cancers in which a p53 mutation was present. Germ-line p53 mutations were not found in any patients whose cancers had p53 mutations. CONCLUSIONS AND IMPLICATIONS: Like p53 mutations in other types of human cancers, those in epithelial ovarian cancers are diverse and occur frequently in exons 5-8. The predominance of transition mutations suggests that p53 mutations in ovarian cancer arise because of spontaneous errors in DNA synthesis and repair rather than the direct interaction of carcinogens with DNA. These molecular data are consistent with data from epidemiologic studies that have failed to demonstrate a convincing relationship between exposure to environmental carcinogens and the development of ovarian cancer.

Alleles↗
PubMed1993

Clinical features and mechanisms of major laparoscopic biliary injury.

Laparoscopic cholecystectomy has quickly become the gold standard for the treatment of symptomatic cholelithiasis. With the introduction of this new technique has come a learning curve, with a higher than expected initial rate of complications. The most significant complication, as with open cholecystectomy, is injury to the bile duct. This article reviews the clinical features and mechanisms of major biliary injury in laparoscopic cholecystectomy.

Bile Ducts↗
PubMed1992

Immune response to p53 is dependent upon p53/HSP70 complexes in breast cancers.

Overexpression of the p53 protein, resulting from gene mutations that increase protein stability, has been detected in greater than 25% of primary human breast cancers. In addition, approximately 10% of breast cancer patients have circulating antibodies to the p53 protein. In this study, the anti-p53 humoral response is correlated with the presence and type of mutant p53 protein expressed in the tumor. In a series of 60 breast cancer patients, 0 of 30 tumors with normal, low-level p53 expression induced anti-p53 antibodies, whereas 7 (23%) of 30 tumors with p53 overexpression elicited a specific anti-p53 antibody response. These 7 patients had anti-p53 antibodies that recognized wild-type p53 and a variety of mutant p53 proteins. A comparison of p53 mutations revealed that antibody-negative tumors had mutations exclusively in exons 7 and 8, whereas antibody-positive tumors had mutations primarily in exons 5 and 6. Moreover, all antibody-eliciting tumors contained complexes between p53 and a 70-kDa heat shock protein, whereas none of the antibody-negative tumors contained this complex. This study implicates a 70-kDa heat shock protein in the antigenic presentation of p53.

Antibodies, Monoclonal↗
PubMed1992

Overexpression and mutation of p53 in endometrial carcinoma.

Immunohistochemical staining for the p53 protein was performed in 107 snap frozen primary endometrial adenocarcinomas and 15 benign uterine tissues using monoclonal antibody PAb1801. No staining was seen in benign samples, whereas intense nuclear staining of cancer cells consistent with overexpression of the p53 protein was observed in 22 of 107 cancers (21%). p53 overexpression was more frequent in advanced (Stage III/IV) cancers (41%) than in early (Stage I/II) cancers (9%) (P less than 0.001), and also was associated with nonendometrioid histology (P = 0.008), positive peritoneal cytology (P = 0.01), extrauterine metastases (P = 0.003), and negative progesterone receptor status (P = 0.04). To confirm the relationship between p53 overexpression and mutation, p53 mRNA from 8 cancers was reverse transcribed and amplified using the polymerase chain reaction. DNA sequencing revealed point mutations in each of the 5 cancers that overexpressed p53, whereas the wild-type sequence was found in 3 cancers that did not overexpress the protein. Each of the 5 mutations resulted in an amino acid substitution in a highly conserved region of the p53 gene where mutations have been found in other cancers. Further studies are warranted to determine whether the association between p53 overexpression and advanced stage disease is due to accumulation of genetic lesions during tumor progression or whether p53 alterations confer a more virulent phenotype.

Adenocarcinoma↗
PubMed1992

Treatment of infantile subglottic hemangioma with electrocautery.

Laryngeal subglottic hemangioma is a rare but potentially life-threatening congenital lesion that can compromise that infant airway. A multitude of medical and surgical modalities have been used in the treatment of this lesion but no single approach has received universal acceptance. Three infants with subglottic hemangiomas were treated successfully with electrocautery; each was managed without tracheostomy. Bronchoscopic electrocautery appears to be a safe, effective, inexpensive way to manage infantile subglottic hemangioma.

Bronchoscopy↗
PubMed1992

The technique of laparoscopic cholecystectomy in children.

Twelve children underwent elective laparoscopic cholecystectomy for symptomatic cholelithiasis during a 10-month period in one institution. The operative technique that has been described for adults was modified because of the smaller dimensions of pediatric patients. These modifications are discussed in this report, as are new alternatives for evaluating the common duct. No operative complications or conversions to open cholecystectomy occurred, and no complications after surgery were seen during an average follow-up period of 4.5 months. The benefits of laparoscopic cholecystectomy include decreased pain and ileus after surgery, shortened hospitalization, and improved cosmesis. Laparoscopic cholecystectomy is safe and efficacious in children, and it compares favorably with traditional cholecystectomy in the pediatric age group.

Adolescent↗
PubMed1992

Mechanisms of major biliary injury during laparoscopic cholecystectomy.

Laparoscopic cholecystectomy has become the procedure of choice for surgical removal of the gallbladder. The most significant complication of this new technique is injury to the bile duct. Twelve cases of bile duct injury during laparoscopic cholecystectomy were reviewed. Eight injuries were of a classic type: misidentification of the common duct for the cystic duct, resection of part of the common and hepatic ducts, and associated right hepatic arterial injury. Another injury was similar: clip ligation of the distal common duct with proximal ligation and division of the cystic duct, resulting in biliary obstruction and leakage. Three complications arose from excessive use of cautery or laser in the region of the common duct, resulting in biliary strictures. Evaluation of persistent diffuse abdominal pain led to the recognition of ductal injury in most patients. Ultimately, 10 patients required a Roux-en-Y hepaticojejunostomy to provide adequate biliary drainage. One patient had a successful direct common duct repair, and the remaining patient underwent endoscopic dilatation.

Adult↗
PubMed1992

Expression of p53 in human neuroblastoma- and neuroepithelioma-derived cell lines.

Overexpression of the nuclear phosphoprotein p53 has been detected in many different transformed human cell lines and primary adult tumors. Elevated steady-state levels of p53 appear to be the result of an increase in the stability of the protein and, in adult cancers, high levels of the protein are associated with mutation of the p53 gene. In this study, overexpression of p53 was detected in 4 out of 5 human neuroblastoma-derived cell lines. The protein expressed by each of these four lines had a significantly prolonged half-life relative to the p53 protein in immortalized rodent fibroblasts and normal bovine adrenal medullary cells. However, no mutations were detected in the highly conserved regions of the p53 gene in these four neuroblastoma lines and the protein being expressed was not recognized by the mutant-specific anti-p53 monoclonal antibody, PAb 240. Upon retinoic acid-induced differentiation of the LA-N-5 neuroblastoma cell line, the level of p53 protein declined, as did the level of p53 mRNA, but the half-life of the protein remained unchanged. The high level of protein observed in the undifferentiated cell lines appears to result from expression of a stable wild-type p53 protein and increased transcription. In contrast, p53 protein was undetectable in two neuroepithelioma-derived cell lines; the p53 gene in one of these lines contained a nonsense mutation, while the other transcribed truncated p53 mRNA.

Base Sequence↗
PubMed1991

Genetic basis for p53 overexpression in human breast cancer.

Overexpression of an activated form of the p53 protein may be involved in neoplastic transformation. We found widespread overexpression of p53 by immunohistochemical staining in 11 (22%) of 49 primary invasive human breast cancers. Northern blot analysis showed that this overexpression was not due to an increase in the steady-state level of p53 mRNA. The p53 gene was directly sequenced in 7 of these tumors with elevated levels of the protein and, in each case, a mutation that altered the coding sequence for p53 was found in a highly conserved region of the gene. Whereas 4 of these tumors contained only a mutant p53 allele, the other 3 tumors exhibited coding sequences from both a mutant and a wild-type allele. p53 mutations have previously been correlated with allelic loss of part of chromosome 17p that contains the p53 locus. Examination of all 49 breast tumors revealed a 61% frequency of deletion at or near the p53 locus. However, the presence of allelic deletion did not correlate with overexpression of the protein. Six tumors that were deleted but did not express high levels of the protein were sequenced and all retained a wild-type p53 allele. In this series of human breast cancers, overexpression of the p53 protein, not allelic loss on chromosome 17p, was always associated with mutation of the p53 gene.

Alleles↗
PubMed1991

Overexpression and mutation of p53 in epithelial ovarian cancer.

We examined p53 expression in 107 epithelial ovarian cancers with immunohistochemical techniques using monoclonal antibody PAb1801. High level expression of nuclear p53 protein was detected in the malignant epithelium in 54 (50%) of these cancers. Expression of p53 protein was undetectable in 13 benign gynecological tissues. p53 mRNA from three cancers that overexpressed the protein were sequenced and point mutations which altered the coding sequence of the highly conserved region of the gene were found in each case. Three cancers with undetectable protein levels also were sequenced and were found to be wild-type through the same region of the gene. As in other cancers, overexpression of the p53 protein in ovarian cancer appears to correlate closely with the presence of mutation in the p53 gene. p53 overexpression did not correlate with stage, histological grade, or the ability to perform optimal cytoreductive surgery. A significant correlation (P = 0.04) was observed between p53 overexpression and aneuploidy in advanced stage (III/IV) disease. There was no significant relationship between overall survival and p53 expression. Since mutation and overexpression of p53 are common in epithelial ovarian cancers, further studies are warranted to clarify the role of p53 in ovarian tumorigenesis.

Amino Acid Sequence↗
PubMed1991

Maintenance of p53 alterations throughout breast cancer progression.

Overexpression of the nuclear phosphoprotein p53 is one of the most common abnormalities in primary human cancer and appears to be due to point mutation within a highly conserved region of the p53 gene which then encodes for a mutant, more stable protein. In this study different stages of breast cancer progression were examined, from in situ to metastatic disease, to determine at what stage mutational activation occurs and whether it is maintained during tumor progression. Two (13%) of 15 pure intraductal tumors expressed high levels of p53 in all malignant epithelial cells. Sequencing of p53 mRNA from one of these tumors demonstrated a nucleotide substitution altering the amino acid composition of the protein. Six (17%) of 35 specimens which contained both in situ and invasive disease expressed high levels of p53. All malignant epithelial cells in these 6 cases stained positively and in no specimen did one component express different levels of the protein than the other growth phase. Sequence analysis of a tissue with significant amounts of both in situ and invasive disease revealed only a single point mutation, without evidence of wild-type nucleotide at the site of substitution, suggesting that p53 mRNA from each component of the tumor contained the same nucleotide substitution. Eleven (50%) of 22 pairs of primary tumors and their lymph node metastases expressed elevated levels of p53, and in each case, expression levels were identical in the primary and secondary sites. Identical mutations were found in the p53 mRNA from two paired primary and metastatic sites. Therefore, mutation within a highly conserved region of the p53 gene leading to overexpression of the protein product can occur in the earliest recognized phase of breast cancer and this alteration is maintained during progression from intraductal to infiltrating carcinoma. Mutations are also conserved during the process of metastatic spread.

Base Sequence↗