Gene conversion is a likely cause of mutation in PKD1

Approximately 70% of the gene responsible for the most common form of autosomal dominant polycystic kidney disease ( PKD1 ) is replicated in several highly homologous copies located more proximally on chromosome 16. We recently have described a novel technique for mutation detection in the duplicated region of PKD1 that circumvents the difficulties posed by these homologs. We have used this method to identify two patients with a nearly identical cluster of base pair substitutions in exon 23. Since pseudogenes are known to be reservoirs for mutation via gene conversion events for a number of other diseases, we decided to test whether these sequence differences in PKD1 could have arisen as a result of this mechanism. Using changes in restriction digest patterns, we were able to show that these sequence substitutions are also present in N23HA, a rodent-human somatic cell hybrid that contains only the PKD1 homologs. Moreover, these changes were also detected in total DNA from several affected and unaffected individuals that did not harbor this mutation in their PKD1 gene copy. This is the first example of gene conversion in PKD1 , and our findings highlight the importance of using gene-specific reagents in defining PKD1 mutations.      

Is laparoscopic treatment of adhesions a valid approach for postoperative abdominal pain?

The role of post-operative adhesions in chronic abdominal pain remains controversial. The aim of this study was to assess the value of laparoscopic treatment of adhesions for chronic post-operative abdominal pain in 32 patients. Over a period of 8 years, 32 patients (25 women and 7 men) with a mean age of 41.5 years (18-69) were hospitalized for chronic abdominal pain of more than 6 months duration, without an obvious underlying neoplasm or psychiatric disorder. They had all undergone at least one previous abdominal operation (mean, 1.9; range, 1-5), with a mean follow-up of 28 months (6-82). The mean duration of the pain was 18 months (6-65) and in 24 of the 32 cases it was mainly hypogastric. Other than the presence of a scar, the clinical examination was completely normal. Prior to hospitalization, 163 different laboratory tests, 162 radiological investigations, including 13 CT scans and 3 MRIs, and 25 endoscopies had been performed. A pneumoperitoneum was made by "open laparoscopy" in 23 cases and with Verres needle in 9 cases. Eight patients (25%) did not have any adhesions, but 6 of them were found to have a gynecological problem (endometriosis). In this group, the laparoscopy lasted 34 minutes (15-45) and the mean hospital stay was 48 hours. In 24 cases, adhesions were found and selected. This was thought to be complete in 22 cases (91.6%). There was a strict correlation between the adhesions and the scar in 85% of cases. In 5 cases, the adhesions were associated with another intervention. There were no conversions. The mean duration of surgery and hospitalization was respectively 56 minutes (32-120) and 3.2 days. There was no mortality and the morbidity rate was 4.1% (1 monopolar injury). The average follow-up was 26.7 months: 22 of the 24 patients who had freeing of adhesions were evaluated after at least 6 months of follow-up. In 10 cases, the pain had completely resolved (45%), in 6 it had decreased (27%) and in 6 cases it was unchanged or had even worsened (1 case of endometriosis). Laparoscopic exploration for chronic post-operative abdominal pain, after an extensive work-up performed after a suitably long delay post-surgery, can be used to detect and treat adhesions in 3/4 cases. In the absence of another lesion, the pain is lessened in 72% cases. However, if there is another lesion, laparoscopic treatment of adhesions is less effective with respect to the pain, but it nevertheless can identify an.     

Laparoscopic splenectomy for hematologic diseases. Study of 275 cases. French Society of Laparoscopic Surgery

AIM OF THE STUDY: To evaluate the results of laparoscopic splenectomy for hematologic diseases by a multicenter retrospective study. PATIENTS AND METHODS: Between 1991 and 1998, 275 patients (mean age: 40.4 years [18-93]) underwent splenectomy for idiopathic thrombocytopenic purpura (ITP) (n = 209, 76%), for hemolytic anemia (HA) (n = 37) including hereditary spherocytosis (n = 13) and auto-immune anemia (n = 24), lymphoma (n = 12), tumor (n = 6) and uncommon hematologic syndromes (n = 11). Laparoscopic splenectomy was attempted in every patient. The lateral approach was most commonly used with an anterior approach to the splenic hilar vessels, which were cut after hemostasis using a stapling gun; other techniques were also employed. RESULTS: The mean operating time was 165 minutes (45-360); it was shorter in the case of conversion (144 minutes) and became shorter with the operator's experience. Conversion was necessary in 55 patients (20%), due to hemorrhage in 2/3 of cases, related to splenic vessels (20 cases), short gastric vessels (9 cases), or injury of the spleen (8 cases). In ten cases (2%), conversion was necessary for extraction of the spleen. Conversion rate varied from 5.3 to 46.7%, depending on the surgical team. Univariate analysis of factors predisposing to conversion identified four causes: obesity; technique used to achieve hemostasis of the splenic hilar vessels; operator's experience; and presence of splenomegaly. An accessory spleen was found in 44 patients (16%). The weight of the spleen was more than 350 g in 43 patients (15.6%). There were no deaths. There were no significant complications in 236 patients (85.8%) and the mean hospital stay was 6.4 days. In comparison with patients who had a conversion, bowel function returned significantly earlier, use of analgesia was reduced and hospital stay was shorter. The overall morbidity rate was 13.8% (n = 38); morbidity rate was only 10.4% (n = 22) for laparoscopic splenectomy. In these 22 patients, the complications were: subphrenic collections (n = 5, 2.2%), abdominal wall infections (n = 5), thromboembolic events (n = 2), anemia (n = 2), pneumonia (n = 1), peptic ulcer (n = 1), bowel obstruction (n = 1), splenic vein thrombosis (n = 1). Re-operations were required in 4 patients (1.8%) because of hemorrhage, pancreatitis and bowel obstruction. Morbidity rate was significantly increased in the case of conversion (27%), obesity (20%), malignant disease (30%) and splenomegaly (21.8%). Forty-four patients (16%) received perioperative or postoperative blood transfusion and 23 (8.3%) received platelet transfusion. Mean time to return to normal activity was 21 days and was shorter in the absence of conversion (18.5 days versus 35 days). In patients with ITP, the mean platelet count was 240,000 after 3 months, and the failure rate was 8.3%. CONCLUSION: Laparoscopic splenectomy is a real alternative to conventional splenectomy for some hematologic diseases, particularly ITP and HA. The advantages are an uneventful postoperative course, a lower morbidity rate, a shorter hospital stay and an earlier return to normal activity. The limits of this technique are related to the operator's experience, the size of the spleen, the nature of the underlying disorders and patient characteristics, mainly obesity.     

Variations in intraperitoneal temperature during laparoscopic cholecystectomy

STUDY AIM: The aim of this study was to measure thermal variation during laparoscopy in the vicinity of heat sources such as monopolar (MC), bipolar (BC) and ultrasound coagulation (USC) and to evaluate their possible negative consequences for the patient. METHODS: This study included 67 patients who underwent laparoscopic cholecystectomy. The temperature measurements were taken with a sterile thermal probe introduced through a 5 mm trocar, coupled with a recording monitor reading variations between 20 degrees and 80 degrees C. The variation in temperature was measured as a function of the power applied to the electrodes (20 or 30 W) and in relation to the distance (1, 2, 3, 4, and 5 cm) from the electrodes. RESULTS: The temperature varied by 3 degrees for BC, 29 degrees for MC and only 0.2 degree for USC when the distance increased for 1 to 5 cm. Depending on the power delivered, (20 or 30 W or 1 to 5 for USC), the variations were 1 degree for BC, 17 degrees for MC and there was still no variation for USC. CONCLUSION: The use of bipolar coagulation and ultrasonic coagulation associated with minimal temperature variations is the option of choice for operating near structures such as the common bile duct or the gastrointestinal tract.     

Shwachman syndrome: Exocrine pancreatic dysfunction and variable phenotypic expression

BACKGROUND & AIMS: Shwachman syndrome is an inherited condition with multisystemic abnormalities, including exocrine pancreatic dysfunction. The aim of this study was to evaluate the occurrence and progression of features in a large cohort of patients. METHODS: Clinical records of 25 patients with Shwachman syndrome were reviewed. RESULTS: Mean birth weight (2.92 +/- 0.51 kg) was at the 25th percentile. However, by 6 months of age, mean heights and weights were less than the 5th percentile. After 6 months of age, growth velocity was normal. Severe fat maldigestion due to pancreatic insufficiency was present in early life (fecal fat, 26% +/- 17% of fat intake; age, < 2 years). Serial assessment of exocrine pancreatic function showed persistent deficits of enzyme secretion, but 45% of patients showed moderate age-related improvements leading to pancreatic sufficiency. Neutropenia was the most common hematologic abnormality (88%), but leukopenia, thrombocytopenia, and anemia were also frequently encountered. Patients with hypoplasia of all three bone marrow cellular lines (n = 11) had the worst prognosis; 5 patients died, 2 of sepsis and 3 of acute myelogenous leukemia. Other findings included hepatomegaly and/or abnormal liver function test results and skeletal abnormalities. CONCLUSIONS: A wide and varied spectrum of phenotypic abnormalities among patients with Shwachman syndrome is described. Pancreatic acinar dysfunction is an invariable abnormality. Patients with severe bone marrow involvement may have a guarded prognosis. (Gastroenterology 1996 Dec;111(6):1593-602)     

Prostaglandin E2 potentiates platelet aggregation by priming protein kinase C

Prostaglandin E2 (PGE2) is produced by activated platelets and by several other cells, including capillary endothelial cells. PGE2 exerts a dual effect on platelet aggregation: inhibitory, at high, supraphysiologic concentrations, and potentiating, at low concentrations. No information exists on the biochemical mechanisms through which PGE2 exerts its proaggregatory effect on human platelets. We have evaluated the activity of PGE2 on human platelets and have analyzed the second messenger pathways involved. PGE2 (5 to 500 nmol/L) significantly enhanced aggregation induced by subthreshold concentrations of U46619, thrombin, adenosine diphosphate (ADP), and phorbol 12-myristate 13-acetate (PMA) without simultaneously increasing calcium transients. At a high concentration (50 mumol/L), PGE2 inhibited both aggregation and calcium movements. PGE2 (5 to 500 nmol/L) significantly enhanced secretion of beta-thromboglobulin (beta TG) and adenosine triphosphate from U46619- and ADP-stimulated platelets, but it did not affect platelet shape change. PGE2 also increased the binding of radiolabeled fibrinogen to the platelet surface and increased the phosphorylation of the 47-kD protein in 32P- labeled platelets stimulated with subthreshold doses of U46619. Finally, the amplification of U46619-induced aggregation by PGE2 (500 nmol/L) was abolished by four different protein kinase C (PKC) inhibitors (calphostin C, staurosporine, H7, and TMB8). Our results suggest that PGE2 exerts its facilitating activity on agonist-induced platelet activation by priming PKC to activation by other agonists. PGE2 potentiates platelet activation at concentrations produced by activated platelets and may thus be of pathophysiologic relevance.     

Autologous bone marrow transplantation in acute myelogenous leukemia: in vitro treatment with myeloid cell-specific monoclonal antibodies

Second or third chemotherapy-induced remissions in acute myelogenous leukemia (AML) are limited by early relapse of the leukemia. We developed monoclonal antibodies (MoAbs) that are cytotoxic to myeloid leukemia cells to treat bone marrow from these patients ex vivo for autologous transplantation. In this pilot study, bone marrow was harvested from ten patients with AML in remission, treated with one or two complement-fixing MoAbs, PM-81 and AML-2-23, which react with myeloid differentiation antigens, incubated with rabbit complement, and cryopreserved. These MoAbs were chosen because they have broad reactivity with AML cells but not with pluripotent progenitor cells. At the time of transplant, 6 patients were in second complete remission, 1 each was in third complete or partial remission, and 2 were in early first relapse. The patients were treated with cyclophosphamide (60 mg/kg a day for 2 days) and total body irradiation (200 cGy twice a day for 3 days) and given infusions of MoAb-treated bone marrow. Full bone marrow reconstitution was observed in eight patients; two patients did not recover platelets. Seven of the ten patients are surviving and disease-free at 21.0, 15.0, 13.0, 10.0, 6.0, 3.0, and 2.0 months posttransplant. Treating bone marrow with MoAbs to myeloid differentiation antigens does not interfere with pluripotential stem cell engraftment. Longer follow-up and a controlled study are necessary to prove that the apparent efficacy of this therapeutic approach in some patients is attributable to MoAb-mediated killing of leukemia cells.