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Biomedical subjects

H W Harris

Publications and source records attributed to H W Harris.

At least 19 recordsLinked to original sources
PubMed2001

Pulmonary dysplasia, Denys-Drash syndrome and Wilms tumor 1 gene mutation in twins.

While a genetic basis for the association of developmental lung and kidney defects has been suspected, the involvement of specific genes in this process is under active investigation. We report such a possible genetic linkage present in identical twins with a mutant Wilms tumor (WT1) gene. Twin girls, born at 35 weeks gestation, manifested symptoms of congenital nephrotic syndrome, renal failure, and severe respiratory abnormalities refractory to assisted ventilation. Both died at 1 month of age. Renal biopsies and autopsy kidney tissue from both the girls revealed diffuse mesangial sclerosis (DMS). Autopsy lung tissue revealed pulmonary dysplasia and hypoplasia in both twins. The WT1 gene from renal tissue in both twins was analyzed for mutations using polymerase chain reaction (PCR) amplification and the single-strand conformation polymorphism (SSCP) technique. Both twins possessed an identical missense mutation in exon 8 of the WT1 gene, resulting in replacement of arginine by histidine at amino acid 366 (arg366his) in the WTI protein. This mutation has previously been described in Denys-Drash syndrome. The WT1 gene plays a role in mesenchymal epithelial (ME) interactions in the developing urogenital system, and possibly has a similar role during lung morphogenesis. We propose that this WT1 gene mutation contributes to both DMS and developmental pulmonary abnormalities by altering ME interactions in both organs.

Female↗
PubMed2001

AQP2 is a substrate for endogenous PP2B activity within an inner medullary AKAP-signaling complex.

We have demonstrated that inner medullary collecting duct (IMCD) heavy endosomes purified from rat kidney IMCD contain the type II protein kinase A (PKA) regulatory subunit (RII), protein phosphatase (PP)2B, PKCzeta, and an RII-binding protein (relative molecular mass ~90 kDa) representing a putative A kinase anchoring protein (AKAP). Affinity chromatography of detergent-solubilized endosomes on cAMP-agarose permits recovery of a protein complex consisting of the 90-kDa AKAP, RII, PP2B, and PKCzeta. With the use of small-particle flow cytometry, RII and PKCzeta were localized to an identical population of endosomes, suggesting that these proteins are components of an endosomal multiprotein complex. (32)P-labeled aquaporin-2 (AQP2) present in these PKA-phosphorylated endosomes was dephosphorylated in vitro by either addition of exogenous PP2B or by an endogenous endosomal phosphatase that was inhibited by the PP2B inhibitors EDTA and the cyclophilin-cyclosporin A complex. We conclude that IMCD heavy endosomes possess an AKAP multiprotein-signaling complex similar to that described previously in hippocampal neurons. This signaling complex potentially mediates the phosphorylation of AQP2 to regulate its trafficking into the IMCD apical membrane. In addition, the PP2B component of the AKAP-signaling complex could also dephosphorylate AQP2 in vivo.

Animals↗
PubMed2000

Extracellular matrix regulates the hepatocellular heat shock response.

BACKGROUND: Cirrhosis is characterized by the accumulation of collagen within the extracellular matrix (ECM) of the liver and progressive hepatocellular dysfunction. Since recent studies have shown that the ECM can modulate cellular function, we examined whether the ECM could contribute to hepatocellular dysfunction. To address this question we examined hepatocyte behavior in two different ECM environments. MATERIALS AND METHODS: Primary rat hepatocytes were cultured as a monolayer on collagen or as multicellular aggregates (spheroids) within a laminin-rich ECM. Hepatocytes were then compared for viability, response to proinflammatory cytokines, and their capacity to activate a heat shock response and adopt a thermotolerant phenotype. In addition, we compared the ability of prior heat shock exposure to protect hepatocytes from tumor necrosis factor (TNF) alpha/actinomycin-D-induced apoptosis in the two different ECM environments. RESULTS: Hepatocytes cultured as a monolayer on collagen exhibited decreased viability, underwent spontaneous apoptosis, and displayed an attenuated cytokine-stimulated nitric oxide production compared to hepatocytes cultured as spheroids. In response to heat, hepatocytes in both ECM environments expressed inducible heat shock protein 70 (hsp72). But, only the hepatocyte spheroids exhibited thermotolerance in response to a subsequent thermal challenge. In contrast to previous reports, induction of the heat shock response failed to protect hepatocytes against TNFalpha-induced apoptosis. CONCLUSIONS: These data demonstrate that the ECM can play an integral role in specific hepatocellular behaviors. Furthermore, the progressive deposition of collagen within the ECM, which is characteristic of fibrotic liver diseases, may directly contribute to the progressive hepatocellular dysfunction observed in cirrhosis. Hepatocellular viability, response to proinflammatory cytokines, heat shock response, and thermotolerance were all altered depending on the composition of the ECM. In contrast, TNFalpha-induced apoptosis was independent of the composition of the ECM.

Animals↗
PubMed2000

Cinematic nuclear scintigraphy reliably directs surgical intervention for patients with gastrointestinal bleeding.

HYPOTHESIS: Cinematic technetium Tc 99m red blood cell ((99m)Tc-RBC) scans, in which real-time scanning is performed and analyzed, can accurately localize gastrointestinal bleeding and thus direct selective surgical intervention. DESIGN: Retrospective medical record review with historical controls. SETTING: Large, university-affiliated public hospital in urban setting. PATIENTS: Twenty-six patients presenting with upper and lower gastrointestinal hemorrhage who underwent cinematic (99m)Tc-RBC scan examinations between 1990 and 1997 and required surgical intervention to control the bleeding. INTERVENTIONS: All patients with gastrointestinal bleeding underwent open surgical procedures to provide cessation of bleeding and resection of appropriate abnormalities. MAIN OUTCOME MEASURES: Patient outcome was based on correlation between preoperative RBC scans and intraoperative findings, surgical pathology, and postoperative clinical course. RESULTS: Twenty-five (96%) of 26 scans were interpreted as positive for gastrointestinal bleeding. In 22 of these 25 scans, the site of bleeding was correctly identified for a sensitivity of 88%. One or more additional diagnostic tests were performed on 19 (73%) of 26 patients, and included angiography and flexible endoscopy. The most common operation performed to control bleeding was a hemicolectomy (14/26). Diverticulosis was the most prevalent diagnosis (46%). Two patients (8%) experienced rebleeding after operation. The overall mortality rate was 19% (5/26). CONCLUSIONS: Cinematic (99m)Tc-RBC scintigraphy is a sensitive, noninvasive alternative to mesenteric angiography for accurately localizing the site of gastrointestinal hemorrhages. As such, this technique can be reliably used to direct selective surgical intervention.

Adult↗
PubMed2000

Functional outcome of patients with femoral head fractures associated with hip dislocations.

Fracture of the femoral head after hip dislocation is a relatively rare injury often associated with a poor functional outcome. Twenty-six patients who sustained femoral head fractures were evaluated using radiographs, clinical examinations, and a validated outcome scoring system. The Short Form-12 was used to assess functional outcome. Patients whose fractures were stabilized with 3-mm cannulated screws and washers had a poor functional outcome. When evaluated with an odds ratio analysis, the use of Kocher-Langenbeck posterior approach was associated with a 3.2 times higher incidence of the patients having avascular necrosis develop when compared with the Smith-Petersen approach. A literature review combined with the current series confirms that the principles of early reduction of hip dislocation, early stabilization, anatomic reduction of the fracture, and rigid fixation are critical principles to attain good results. The Brumback classification system provides superior differentiation of different fracture types when compared with the Pipkin classification. The Smith-Petersen anterior surgical approach is recommended for the majority of patients with femoral head fractures. Three-millimeter cannulated screws with threaded washers are contraindicated for use in stabilizing femoral head fractures, and should not be used in any joint because of dissociation between the screw and the washer.

Adolescent↗
PubMed2000

Substance P dependence of endosomal fusion during bladder inflammation.

Urinary bladder instillation of ovalbumin into presensitized guinea pigs stimulates rapid development of local bladder inflammation. Substance P is an important mediator of this inflammatory response, as substance P antagonists largely reverse the process. Vacuolization of the subapical endosomal compartment of the transitional epithelial cells lining the bladder suggests that changes in endosomal trafficking and fusion are also part of the inflammatory response. To test directly for substance P mediation of changes in endosomal fusion, we reconstituted fusion of transitional cell endosomes in vitro using both cuvette-based and flow cytometry energy transfer assays. Bladders were loaded with fluorescent dyes by a hypotonic withdrawal protocol before endosomal isolation by gradient centrifugation. Endosomal fusion assayed by energy transfer during in vitro reconstitution was both cytosol and ATP dependent. Fusion was confirmed by the increase in vesicle size on electron micrographs of fused endosomal preparations compared with controls. In inflamed bladders, dye uptake was inhibited 20% and endosomal fusion was inhibited 50%. These changes are partly mediated by the neurokinin-1 (NK1) receptor (NK1R), as 4 mg/kg of CP-96,345, a highly selective NK1 antagonist, increased fusion in inflamed bladders but had no effect on control bladders. The receptor-mediated nature of this effect was demonstrated by the expression of substance P receptor mRNA in rat bladder lumen scrapings and by the detection of the NK1R message in guinea pig subapical endosomes by Western blot analysis. The NK1Rs were significantly upregulated following induction of an inflammatory response in the bladder. These results demonstrate that 1) in ovalbumin-induced inflammation in the guinea pig bladder, in vitro fusion of apical endosomes is inhibited, showing endocytotic processes are altered in inflammation; 2) pretreatment in vivo with an NK1R antagonist blocks this inhibition of in vitro fusion, demonstrating a role for NK1R in this process; and 3) the NK1R is present in higher amounts in apical endosomes of inflamed bladder, suggesting changes in translation or trafficking of the NK1R during the inflammatory process. This suggests that NK1R can change the fusion properties of membranes in which it resides.

Animals↗
PubMed2000

The lipemia of sepsis: triglyceride-rich lipoproteins as agents of innate immunity.

Bacterial endotoxin (LPS) elicits dramatic responses in the host including elevated plasma lipid levels due to the increased synthesis and secretion of triglyceride (TG)-rich lipoproteins by the liver, and the inhibition of lipoprotein lipase. This cytokine-induced hyperlipoproteinemia, clinically termed the "lipemia of sepsis", was customarily thought to represent the mobilization of lipid stores to fuel the host response to infection. However, since lipoproteins can also bind and neutralize LPS, we hypothesize that TG-rich lipoproteins (VLDL and chylomicrons) are also components of an innate, non-adaptive host immune response to infection. Herein we review data demonstrating the capacity of lipoproteins to bind LPS, protect against LPS-induced toxicity, and modulate the overall host response to this bacterial toxin. Lastly, we propose a pathway whereby lipoprotein-bound LPS may represent a novel, endogenous mechanism for regulating the hepatic acute phase response.

Acute-Phase Reaction↗
PubMed1999

Diet-induced protection against lipopolysaccharide includes increased hepatic NO production.

The host response to Gram-negative infection includes the elaboration of numerous proinflammatory agents, including tumor necrosis factor alpha (TNFalpha) and nitric oxide (NO). A component of the hepatic response to infection is an elevation in serum lipids, the so-called "lipemia of sepsis," which results from the increased production of triglyceride (TG)-rich lipoproteins by the liver. We have postulated that these lipoproteins are components of a nonadaptive, innate immune response to endotoxin [lipopolysaccharide (LPS)] and have previously demonstrated the capacity of TG-rich lipoproteins to protect against endotoxicity in rodent models of sepsis. Herein we report the capacity of a high-fructose diet to protect against LPS, most likely by inducing high circulating levels of endogenous TG-rich lipoproteins. The protective phenotype included the increased production of NO by hepatic endothelial cells. Rats, made hypertriglyceridemic by fructose feeding, experienced decreased LPS-induced mortality (P < 0.03) and systemic TNFalpha levels (P < 0.05) as compared with normolipidemic (chow-fed) controls. The increased survival was associated with elevated levels of inducible NO synthase (NOS2) mRNA levels and NO production (82 +/- 26 vs 3 +/- 3 nmol nitrite/10(6) cells, P < 0.001) by hepatic endothelial cells. Nonselective NOS inhibitors reversed the protective phenotype in vivo and readily decreased NO production by cultured endothelial cells from hypertriglyceridemic rats in vitro. This study suggests that a high-fructose diet can protect against endotoxicity in part through induction of endogenous TG-rich lipoproteins and hepatic endothelial cell NO production. This is the first report of diet-induced hyperlipoproteinemia and subsequent protection against endotoxemia.

Animals↗
PubMed1999

Leukocytosis and free fluid are important indicators of isolated intestinal injury after blunt trauma.

BACKGROUND: The detection of isolated intestinal injuries after blunt trauma can be difficult because of subtle signs and symptoms, often leading to delayed diagnosis. We hypothesized that specific clinical indicators could be identified to assist in the diagnosis of these injuries. METHODS: Medical records of all patients with such injuries from 1988 to 1996 were reviewed. The patients were stratified into those operated on within 6 hours of presentation (apparent injury) and those operated on after 6 hours (occult injury), and the data were compared. RESULTS: Forty-six patients with isolated intestinal injuries were identified. There were no differences in the rate of peritonitis or free fluid on abdominal computed tomography, blood loss, intraoperative findings, or morbidity and mortality between groups. Leukocytosis (sensitivity, 84.8%; specificity, 55.2%; p = 0.01) and free fluid on computed tomography were frequently present, however, and their significance was underappreciated in the occult injury group. CONCLUSION: After blunt abdominal trauma in patients without obvious indications for invasive evaluation of the abdomen (e.g., peritoneal lavage, laparoscopy, laparotomy), leukocytosis can indicate an intestinal injury. Additionally, unexplained free fluid on abdominal computed tomography must be aggressively evaluated.

Adolescent↗
PubMed1999

Modulation of vasopressin-elicited water transport by trafficking of aquaporin2-containing vesicles.

Vasopressin or AVP regulates water reabsorption by the kidney inner medullary collecting duct (IMCD) through the insertion and removal of aquaporin (AQP) 2 water channels into the IMCD apical membrane. AVP-elicited trafficking of AQP2 with the apical membrane occurs via a specialized population of vesicles that resemble synaptic vesicles in neurons. AQP2 vesicles and the IMCD apical membrane contain homologs of vesicle-targeting and signal transduction proteins found in neurons. Expression studies of AQP2, including human AQP2 mutants, suggest that the carboxyl-terminal domain of AQP2 is important in AQP2 trafficking, particularly as a site for cAMP-dependent protein kinase phosphorylation. These present data reveal that IMCD cells possess a complex integrated-signaling and vesicle-trafficking machinery that provides integration of AVP-elicited water transport with many other parameters within the IMCD cell as well as kidney.

Animals↗
PubMed1998

Disulfide bonds in the extracellular calcium-polyvalent cation-sensing receptor correlate with dimer formation and its response to divalent cations in vitro.

Extracellular calcium/polyvalent cation-sensing receptors (CaR) couple to G proteins and contain highly conserved extracellular cysteine residues. Immunoblotting of proteins from rat kidney inner medullary collecting duct endosomes with CaR-specific antibodies reveals alterations in the apparent molecular mass of CaR depending on protein denaturation conditions. When denatured by SDS under nonreducing conditions, CaR migrates as a putative dimeric species of 240-310 kDa. This is twice the predicted molecular mass of the CaR monomer observed after SDS denaturation in the presence of sulfhydryl-reducing agents. In sucrose density gradients, Triton X-100-solubilized CaR sediments as a 220-kDa complex, not explainable by binding of G proteins to CaR monomers. Treatment of Triton-soluble CaR with divalent (Ca2+, Mg2+) and trivalent (Gd3+) metal ion CaR agonists, but not monovalent ions (Na+), partially shifts the electrophoretic mobility of CaR under reducing conditions from a predominantly monomeric to this putative dimeric species on immunoblots in a manner similar to their rank order of functional potency for CaR activation (Gd3+ >> Ca2+ > Mg2+). This Ca2+ effect is blocked by pretreatment with N-ethylmaleimide. We conclude that disulfide bonds present in CaRs mediate formation of dimers that are preserved in Triton X-100 solution. In addition, CaR exposure to Ca2+ induces formation of additional disulfide bonds within the Triton-soluble CaR complex.

Animals↗
PubMed1998

Chylomicrons alter the hepatic distribution and cellular response to endotoxin in rats.

Chylomicrons (CM) can bind endotoxin (lipopolysaccharide [LPS]), forming CM-LPS complexes, and protect against endotoxic shock and death in rodent models of gram-negative sepsis. The liver appears to play a central role in this process, as demonstrated by the increased uptake of LPS by this organ. We examined the effect of CM on the uptake and cellular response to injected 125I-LPS by hepatocytes and hepatic nonparenchymal cells. Whereas CM increased the uptake of LPS by both hepatocytes and Kupffer cells, the increase was proportionately greater in hepatocytes than Kupffer cells. Importantly, CM-LPS complexes inhibited inducible nitric oxide synthase (iNOS) mRNA expression and NO production in Kupffer cells and endothelial cells, reducing mRNA levels by 45% to 50% as compared with LPS alone. CM-bound LPS also reduced NO production by hepatocytes in response to cytokine stimulation. Lastly, CM-LPS complexes yielded a concentration-dependent inhibition of LPS-induced tumor necrosis factor alpha (TNF-alpha) production by Kupffer cells in vitro. These data indicate that the mechanism by which CM protect against endotoxicity may involve an increased uptake of LPS by hepatocytes. Moreover, uptake of CM-bound LPS by liver cells attenuates the capacity of these cells to respond to proinflammatory stimulation. These results highlight important anti-inflammatory properties of CM.

Animals↗
PubMed1998

Obstructive jaundice alters Kupffer cell function independent of bacterial translocation.

BACKGROUND: There is a high incidence of perioperative morbidity and mortality in patients with obstructive jaundice. The absence of bile in the gastrointestinal tract promotes bacterial overgrowth and the increased translocation of bacteria and endotoxin to the liver which has been postulated to inhibit Kupffer cell function in these patients. But, biliary tract obstruction can directly damage liver cells and thus alter their function. Thus, we hypothesized that obstructive jaundice alone alters Kupffer cell function independent of the effects of bacterial translocation. This study was designed to evaluate the contribution of bacterial translocation to the altered Kupffer cell function observed in patients with obstructive jaundice. METHODS: Sprague-Dawley rats were randomized to three groups of six animals each. Group 1 underwent common bile duct ligation with intestinal bile salt replacement (sodium taurocholate 100 mg/kg/day) via gastrostomy and an implantable osmotic pump (CBDL + bile salts), Group 2 underwent common bile duct ligation with normal saline replacement (CBDL + saline), and Group 3 underwent a sham operation (sham control). After 7 days, tissue and blood were collected for bacterial translocation and biochemical analyses. Examination of cultured Kupffer cell function included measuring the phagocytosis of heat-killed Candida albicans and endotoxin (LPS)-induced TNFalpha and nitric oxide production. RESULTS: While bacterial translocation and cecal bacterial counts were significantly increased in the CBDL + saline group, these parameters were both reduced to control levels following intestinal bile salt replacement (CBDL + bile salts). Altered Kupffer cell function, as measured by the increased phagocytosis of C. albicans and LPS-induced NO production, and decreased LPS-induced TNFalpha production were observed in all animals with obstructive jaundice regardless of bile salt replacement. CONCLUSION: Kupffer cell function appears to be differentially affected by obstructive jaundice and these altered functions can occur independent of bacterial translocation.

Animals↗
PubMed1998

Changing management of gallstone disease during pregnancy.

BACKGROUND: Symptomatic gallstones may be problematic during pregnancy. The advisability of laparoscopic cholecystectomy (LC) is uncertain. The objective of this study is to define the natural history of gallstone disease during pregnancy and evaluate the safety of LC during pregnancy. METHODS: Review of medical records of all pregnant patients with gallstone disease at the University of California, San Francisco, from 1980 to 1996. RESULTS: Of approximately 29,750 deliveries, 47 (0.16%) patients were treated for gallstone disease, including biliary colic in 33, acute cholecystitis in 12, and pancreatitis in two. Conservative treatment was attempted in all patients but failed in 17 (36%) cases. Two patients required combined preterm Cesarean-section cholecystectomy and 10 required surgery in the early postpartum period for persistent symptoms. Seventeen patients required cholecystectomy during pregnancy for biliary colic (10), acute cholecystitis (six), and pancreatitis (one). Three patients were treated with open cholecystectomy. Fourteen patients underwent LC at a mean gestational age of 18.6 weeks, mean OR time of 74 min, and mean length of stay of 1.2 days. Hasson cannulation was utilized in 11 patients. Reduced-pressure pneumoperitoneum (6-10 mmHg) was used in seven patients. Prophylactic tocolytics were used in seven patients, with transient postoperative preterm labor observed in one. There were no open conversions, preterm deliveries, fetal loss, teratogenicity, or maternal morbidity. CONCLUSIONS: In past years, symptomatic gallstones during pregnancy were managed conservatively or with open cholecystectomy. LC is a feasible and safe method for treating severely symptomatic patients.

Adult↗
PubMed1998

Membranous glomerulonephritis and nephrosis post factor IX infusions in hemophilia B.

Children with hemophilia B who receive exogenous factor IX infusions may rarely develop inhibitors to the exogenous factor IX and require desensitization. Nephrotic syndrome has recently been described in some of these children. We report the renal clinicopathological findings in a child with severe factor IX deficiency, requiring induction of an immune tolerance protocol, who developed nephrotic syndrome. Renal biopsy revealed peripheral capillary wall thickening and a spike appearance consistent with membranous glomerulonephritis. Electron microscopy showed prominent deposits throughout the thickness of the basement membrane. Factor IX dose reduction was accompanied by reversal of the child's nephrotic syndrome without relapses.

Child, Preschool↗
PubMed1998

Recurrent pyogenic cholangitis.

BACKGROUND: Recurrent pyogenic cholangitis is a complex biliary tract disease characterized by intrahepatic pigment stones, endemic to Southeast Asia and seen with increasing frequency in the United States. The purpose of this study was to review the management of this disorder in a county hospital. METHODS: A retrospective review of 45 patients with recurrent pyogenic cholangitis evaluated between 1984 and 1995. The clinical and surgical management of patients with localized versus bilateral hepatolithiasis were compared. RESULTS: The prevalence of recurrent pyogenic cholangitis at our hospital has more than doubled since 1983. Fourteen of 45 patients (31%) had bilateral disease and required more abdominal computed tomography scans (P < 0.01), percutaneous cholangiograms (P < 0.05), endoscopies (P < 0.01), clinic visits (P < 0.05), and hospital admissions (P < 0.02) as compared with patients with localized disease. CONCLUSIONS: The effective treatment of recurrent pyogenic cholangitis requires definition of the patients' intrahepatic distribution of disease, prior to surgical intervention, and the coordinated efforts of gastroenterologists, radiologists, and surgeons.

Adult↗
PubMed1998

Ciprofloxacin overdose: acute renal failure with prominent apoptotic changes.

Acute renal failure due to ciprofloxacin has been well described. The previously reported cases have been consistent both clinically and pathologically with tubulointerstitial nephritis (TIN). We report a case of ciprofloxacin overdose leading to acute renal failure characterized by acute tubular necrosis (ATN). The outstanding features in the patient's renal biopsy were those of distal nephron apoptosis, best seen in plastic-embedded sections and electron microscopy. This report shows that the distal nephron can be singularly involved in acute renal failure and that electron microscopy or plastic-embedded sections may be necessary to define its involvement.

Acute Kidney Injury↗