Reusable biopsy forceps: a prospective evaluation of cleaning, function, adequacy of tissue specimen, and durability

BACKGROUND: Recent studies have indicated that reusable biopsy forceps remain contaminated after reprocessing and can only be used a mean of 12 to 25 times without malfunction. Because this contradicts traditional endoscopic practice, our study investigated the ability to sterilize a type of commercially available biopsy forceps and prospectively evaluated their function in vivo until malfunction and/or breakage. METHODS: Thirty reusable biopsy forceps were studied, 15 of which were contaminated for 5 trials each with 10(6) Bacillus stearothermophilus, and 15 of which were prospectively evaluated clinically over an 18-month period (9/98-3/00). Contaminated forceps were reprocessed by using a standard protocol and placed in a sterile bag containing soy broth. The latter was passed through a 0.2 micron filter and was subsequently cultured. In vivo data included biopsy site, size, adequacy, problems obtaining a biopsy specimen, and reasons for ultimate forceps failure. RESULTS: After contamination, all biopsy forceps yielded a heavy growth of B stearothermophilus. No forceps, including 5 that were piecemeal dismantled with a wire cutter, had residual bacteria after reprocessing. In the in vivo study, 1507 biopsy sessions were undertaken in 1339 procedures. Forceps were categorized as new or like-new in 1259 of 1339 (94%) procedures, some loss of function but usable in 72 of 1339 (5.4%), and inadequate function or broken at use in 8 of 1339 (0.6%). Histologically, 1501 specimen sets were adequate (99.6%) and mean specimen size was 2.7 +/- 0.1 mm. Mechanical problems were noted in only 38 of 1507 (3%) sessions to include such things as sticky forceps, and the mean number of uses to malfunction or breakage was 91 +/- 15 (SEM) (range 19-132). CONCLUSIONS: This reusable biopsy forceps can be sterilized and used a mean of 91 times with adequate tissue sampling. Mechanical problems were minor to time of breakage. Contingent on acquisition and reprocessing costs as well as the number of procedures performed, this reusable forceps has the potential for significant cost savings.     

Small intestine glutaminase deficiency in celiac disease

Summary Human small intestine contains glutaminase I, an enzyme responsible for the deamination of glutamine. Glutaminase activity was assayed in the jejunal mucosa of patients with celiac disease and of control subjects. Enzymatic activity was markedly diminished in the jejunal biopsy specimens from these patients at the time the diagnosis of celiac disease was made, compared with glutaminase I levels from control subjects. With successful treatment on a gluten-free diet, small-intestinal glutaminase I values returned toward normal as the biopsy specimens improved histologically. Patients with celiac disease who continued to have some symptoms had biopsy evidence of moderately severe mucosal damage, and they maintained low enzyme levels. The patients with abnormal biopsies due to other small-bowel diseases also had diminished glutaminase I activity. This study suggests that patients with untreated celiac disease have a secondary deficency of this enzyme.Supported by Grants AM-5156 and AM-08870 from the National Institutes of Health, U. S. Public Health Service. The patients studied in this work were hospitalized on the Yale University Clinical Research Center, supported by USPHS Grant FR-00125.     

Insulin sensitivity of protein and glucose metabolism in human forearm skeletal muscle.

Physiologic increases of insulin promote net amino acid uptake and protein anabolism in forearm skeletal muscle by restraining protein degradation. The sensitivity of this process to insulin is not known. Using the forearm perfusion method, we infused insulin locally in the brachial artery at rates of 0.00 (saline control), 0.01, 0.02, 0.035, or 0.05 mU/min per kg for 150 min to increase local forearm plasma insulin concentration by 0, approximately 20, approximately 35, approximately 60, and approximately 120 microU/ml (n = 35). L-[ring-2,6-3H]phenylalanine and L-[1-14C]leucine were infused systemically, and the net forearm balance, rate of appearance (Ra) and rate of disposal (R(d)) of phenylalanine and leucine, and forearm glucose balance were measured basally and in response to insulin infusion. Compared to saline, increasing rates of insulin infusion progressively increased net forearm glucose uptake from 0.9 mumol/min per 100 ml (saline) to 1.0, 1.8, 2.4, and 4.7 mumol/min per 100 ml forearm, respectively. Net forearm balance for phenylalanine and leucine was significantly less negative than basal (P < 0.01 for each) in response to the lowest dose insulin infusion, 0.01 mU/min per kg, and all higher rates of insulin infusion. Phenylalanine and leucine R(a) declined by approximately 38 and 40% with the lowest dose insulin infusion. Higher doses of insulin produced no greater effect (decline in R(a) varied between 26 and 42% for phenylalanine and 30-50% for leucine). In contrast, R(d) for phenylalanine and leucine did not change with insulin. We conclude that even modest increases of plasma insulin can markedly suppress proteolysis, measured by phenylalanine R(a), in human forearm skeletal muscle. Further increments of insulin within the physiologic range augment glucose uptake but have little additional effect on phenylalanine R(a) or balance. These results suggest that proteolysis in human skeletal muscle is more sensitive than glucose uptake to physiologic increments in insulin.     

Selective expansion of T cells expressing V beta 2 in toxic shock syndrome

Infection with Staphylococcus aureus and the production of toxic shock syndrome toxin-1 (TSST-1) have been implicated in the pathogenesis of toxic shock syndrome. Previous in vitro studies have demonstrated that TSST-1 is a powerful but selective stimulator of human T cells, and that the majority of activated cells express the TCR V beta 2 gene segment. We therefore studied patients with toxic shock syndrome using a modification of the PCR to determine if expansion of V beta 2+ T cells is a marker of the in vivo disease process. Five of eight patients studied demonstrated markedly elevated levels of circulating V beta 2+ T cells, whereas none showed significantly elevated levels of T cells expressing other V beta gene segments. The results suggest that toxin-mediated T cell activation, which involves a large fraction of the human T cell repertoire, may be critical in the pathogenesis of this disease.     

Activation of Ca2+-dependent K+ channels in human B lymphocytes by anti-immunoglobulin.

Many mammalian cell types exhibit Ca2+-dependent K+ channels, and activation of these channels by increasing intracellular calcium generally leads to a hyperpolarization of the plasma membrane. Their presence in B lymphocytes is as yet uncertain. Crosslinking Ig on the surface of B lymphocytes is known to increase the level of free cytoplasmic calcium ([Ca2+]i). However, rather than hyperpolarization, a depolarization has been reported to occur after treatment of B lymphocytes with anti-Ig. To determine if Ca2+-dependent K+ channels are present in B lymphocytes, and to examine the relationship between intracellular free calcium and membrane potential, we monitored [Ca2+]i by means of indo-1 and transmembrane potential using bis(1,3-diethylthiobarbituric)trimethine oxonol in human tonsillar B cells activated by anti-IgM. Treatment with anti-IgM induced a biphasic increase in [Ca2+]i and a simultaneous hyperpolarization. A similar hyperpolarization was induced by ionomycin, a Ca2+ ionophore. Delaying the development of the [Ca2+]i response by increasing the cytoplasmic Ca2+-buffering power delayed the hyperpolarization. Conversely, eliminating the sustained phase of the [Ca2+]i response by omission of external Ca2+ abolished the prolonged hyperpolarization. In fact, a sizable Na+-dependent depolarization was unmasked. This study demonstrates that in human B lymphocytes, Ca2+-dependent K+ channels can be activated by crosslinking of surface IgM. Moreover, it is likely that, by analogy with voltage-sensitive Ca2+ channels, Na+ can permeate through these ligand-gated Ca2+ "channels" in the absence of extracellular Ca2+.     

Response of Variant Hereditary Angioedema Phenotypes to Danazol Therapy: GENETIC IMPLICATIONS

Hereditary angioedema (HAE), an auto-somal dominant disorder characterized by attacks of episodic edema is associated with decreased functional levels of the C1 esterase inhibitor. Approximately 85% of patients have lowered antigen levels of a normal inhibitor protein. 15% of patients have normal or elevated antigenic levels of functionless protein. We have examined the response to danazol therapy of patients with the variant HAE phenotypes possessing the abnormal protein in an effort to determine if these patients possess a normal structural C1 inhibitor allele. Four patients with a variant HAE phenotype were treated successfully with danazol. In two patients, distinguished by the presence of a functionless, albumin-bound, C1 inhibitor (phenotype 2), phenotypic analysis of the danazol response by bidirectional immunoelectrophoresis revealed the appearance of the normal C1 inhibitor gene product during danazol therapy. This relatively cathodal C1 inhibitor peak appears in conjunction with the development of nearly normal functional activity. All of the functional C1 inhibitory activity which appeared in the phenotype 2 treatment serum was associated with the electrophoretically normal inhibitor. This normal protein could be separated from the functionless inhibitor protein by immunoadsorption and molecular sieve chromatography. Danazol therapy of the two patients with an electrophoretically normal, functionless C1 inhibitor (phenotype 3) also resulted in a clinical remission associated with development of a significant increment in functional serum C1 inhibitory activity and C1 inhibitor protein. These findings demonstrate that these two HAE phenotypic variants are heterozygous for the normal serum C1 inhibitor, a finding which was not apparent before phenotypic analysis of this serum during danazol therapy. These data provide strong evidence for a basic similarity between the common form of HAE and its phenotypic variants. They also suggest that a structural gene lesion may result in the abnormalities of serum C1 inhibitor function and disease expression in all three of these HAE phenotypes.     

Characterization of mechanisms of resistance to beta-lactam antibiotics in methicillin-resistant strains of Staphylococcus saprophyticus.

The resistance mechanisms of methicillin-resistant strains of Staphylococcus saprophyticus were characterized. Penicillin-binding protein (PBP) studies demonstrated an inducible PBP identical to PBP 2a in the membranes of these isolates. The amount of beta-lactamase produced was minimal. PBP 2a is responsible for the methicillin resistance observed in these strains of S. saprophyticus.     

Brain abscesses associated with right-to-left shunts in adults

Although brain abscesses are frequently cryptogenic in origin, bacteria must reach the brain either by direct or hematogenous spread. Right-to-left shunts, caused either by intrapulmonary vascular malformations or congenital heart defects, may allow microorganisms to evade the normal host defenses in the lungs and lead to development of brain abscesses. Two patients recently presented with brain abscesses and were found to have conditions associated with right-to-left shunts. The diagnosis of brain abscess should prompt the clinician to consider right-to-left shunts as a possible predisposing condition for brain abscess.