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Biomedical subjects

R L Friedman

Publications and source records attributed to R L Friedman.

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

Magnetic resonance imaging of the anterior cruciate ligament: current concepts.

MR imaging of the anterior cruciate ligament (ACL) can provide highly accurate information and is the most diagnostic current imaging procedure for suspected injuries to the ligament. It is safe, absent of ionizing radiation, non-invasive, and tolerated well by patients. There have been significant advances in technique and the ability to interpret images. One can expect sensitivities of 92% to 96% and specificities of 92% to 98%. This imaging test of the ACL can provide useful information in establishing the normal anatomy, diagnosing tears, and studying the reconstructed graft.

Anterior Cruciate Ligament↗
PubMed1995

Secondary cytoreductive surgery for recurrent ovarian cancer. A prospective study.

BACKGROUND: The prognosis for patients with recurrent epithelial ovarian cancer is poor. Most are treated with salvage chemotherapy. The role of secondary cytoreductive surgery is controversial. Hence, this prospective study was undertaken to determine the feasibility and benefit of secondary cytoreductive surgery before the administration of salvage chemotherapy. METHODS: Between 1990 and 1994, 36 patients with recurrent epithelial ovarian cancer underwent secondary surgical cytoreduction. All had prior primary cytoreductive surgery, platin-based chemotherapy, and had relapsed at least 6 months after completion of primary treatment. The goal was the excision of all macroscopic disease before initiation of chemotherapy or radiation therapy. Statistical analysis was undertaken to determine which clinical and pathologic variables influenced the feasibility of complete excision as well as morbidity, mortality, survival benefit, and quality of life resulting from secondary cytoreductive surgery. RESULTS: Thirty (83.0%) patients had complete surgical excisions. The probability of a complete excision was influenced by Gynecologic Oncology Group (GOG) performance status (0-2 vs. 3, P = 0.05) and size of largest tumor deposit (< 10 cm vs. > 10 cm, P = 0.03). Eleven (30.1%) patients experienced morbidity and 1 (2.8%) died postoperatively. Of 27 symptomatic patients with at least 3 months of follow-up, 26 (96.2%) had resolution or improvement of their symptoms. Of 25 followed for at least 6 months postoperatively, 23 (92.0%) had a GOG performance status of 0 or 1. Survival was adversely influenced by the administration of salvage chemotherapy before surgery (P = 0.02), a preoperative GOG performance status of 3 (P = 0.01), and a brief disease free interval after completion of primary treatment (P = 0.01). The median survival was extended for patients completely resected before salvage chemotherapy or radiation, compared with those with macroscopic residual disease remaining (43 vs. 5 months, P = 0.03). CONCLUSIONS: Complete secondary cytoreductive surgery for recurrent epithelial ovarian cancer is technically feasible and has an acceptable operative complication rate. Survival is significantly improved for patients having complete resection. Subsequent relief of symptoms and performance status are excellent.

Aged↗
PubMed1995

Acute cholecystitis with calculous biliary duct obstruction in the gravid patient. Management by ERCP, papillotomy, stone extraction, and laparoscopic cholecystectomy.

The pregnant patient with cholelithiasis is subject to the manifold complications associated with this disease. The management of a gravid patient with acute cholecystitis complicated by biliary duct obstruction utilizing combined endoscopic therapy and laparoscopic cholecystectomy is reported. The benefits to the patient and fetus when successful are apparent, but it is important to anticipate potential problems associated with laparoscopy in pregnancy and to avoid them. Various safeguards such as fetal monitoring, careful trocar placement, and intra-abdominal pressure monitoring have been suggested and should be appropriately utilized to enable a satisfactory outcome. Case reports such as this may further clarify the interdependent role of laparoscopic cholecystectomy and ERCP and their application to the pregnant patient.

Acute Disease↗
PubMed1995

The relationship between subacromial space pressure, blood pressure, and visual clarity during arthroscopic subacromial decompression.

Twenty-two consecutive patients with subacromial impingement syndrome underwent arthroscopic subacromial decompression. Measurements of the subacromial space pressure and the blood pressure were recorded along with the clarity of the visual field. The clarity of the visual field was objectively determined based on the pressure at which bleeding was observed from trabecular bone or the soft tissue capillaries. A direct correlation was found between systolic blood pressure (SBP), subacromial space pressure (SASP), and the clarity of the visual field. On average, maintaining a pressure difference (SBP-SASP) of 49 mm Hg or less prevented bleeding and permitted good visualization. With a greater differential, significant bleeding occurred. Furthermore, the use of relative hypotensive anesthesia permits lower irrigation pressures and significantly reduces the risk of fluid extravasation into the subcutaneous tissues of the shoulder.

Acromion↗
PubMed1995

Identification of a Bordetella pertussis regulatory factor required for transcription of the pertussis toxin operon in Escherichia coli.

Transcription of the pertussis toxin operon (ptx) is positively regulated in Bordetella pertussis by the bvgAS locus. However, a ptx-lacZ transcriptional fusion in Escherichia coli cannot be activated by bvgAS in trans. This suggests that an additional factor(s) is required for transcription of ptx. A gene encoding a Bvg accessory factor (Baf) was identified by its ability to activate an E. coli ptx-lacZ fusion in the presence of bvgAS. The expression of ptx-lacZ was decreased by the addition of 40 mM MgSO4, a compound that also modulates ptx expression in B. pertussis. Baf alone did not activate expression of an E. coli fhaB-lacZ fusion, nor did it increase expression of fhaB-lacZ in trans with bvgAS. The gene encoding Baf was localized, sequenced, and found to produce a novel 28-kDa protein. Sequences homologous to B. pertussis baf were identified in Bordetella bronchiseptica and Bordetella parapertussis but not in Bordetella avium. When an additional copy of baf was integrated into the chromosome of BC75, a B. pertussis mutant that produces a low level of pertussis toxin, pertussis toxin production was partially complemented in the cointegrate strain.

Amino Acid Sequence↗
PubMed1994

Characterization of the gene encoding superoxide dismutase of Bordetella pertussis and construction of a SOD-deficient mutant.

The Bordetella pertussis gene sodB, encoding superoxide dismutase (SOD), was cloned by complementation of an Escherichia coli sodAsodB double mutant. The nucleotide sequence of sodB predicted a 21-kDa protein with homology to manganese- and iron-containing SODs from other organisms. Examination of SOD activity on gels suggests that B. pertussis extracts have a single SOD containing Fe3+ as a prosthetic group. A SOD-deficient mutant was obtained by insertional inactivation of sodB in B. pertussis, confirming that there is only one SOD in this organism.

Amino Acid Sequence↗
PubMed1994

Pneumothorax associated with laparoscopic cholecystectomy.

Pneumothorax is an uncommon but potentially serious complication that can occur during laparoscopic procedures. A patient under-going laparoscopic cholecystectomy developed an 80% pneumothorax during the course of the procedure and required chest tube insertion. She then underwent an uneventful recovery. The etiology of this complication as well as methods for avoiding this problem have been reviewed. Because of the potential serious nature of this complication, it is imperative that the surgeon be aware of the possibility and implement appropriate immediate therapy.

Adult↗
PubMed1994

Molecular characterization of catalase from Bordetella pertussis: identification of the katA promoter in an upstream insertion sequence.

In this report we evaluate the role of catalase in the survival of Bordetella pertussis within human polymorphonuclear leukocytes (PMNs). Crude extracts of B. pertussis exhibited a single catalase activity when subjected to non-denaturing polyacrylamide gel electrophoresis and assayed for catalase activity. A plasmid containing B. pertussis katA was identified by complementation of UM255, a catalase-deficient strain of Escherichia coli. The nucleotide sequence of katA predicts a 55 kDa protein that shares homology with a class of haem-containing catalases found in both eubacteria and eukaryotes. Analysis of the nucleotide sequence upstream of katA revealed the presence of a copy of IS481, a B. pertussis-specific insertion sequence. The start site of transcription of katA was mapped to a T residue in IS481 by primer extension analysis performed with B. pertussis RNA and a katA-specific primer. A catalase-deficient strain of B. pertussis, DD900, was constructed by gene replacement. DD900 was more sensitive to killing by 1 and 5 mM H2O2 than the parental strain, BP339. However, there was no difference in the ability of DD900 and BP339 to survive for 2 h in human PMNs. This suggests that catalase plays no significant role in the survival of B. pertussis within PMNs.

Base Sequence↗
PubMed1994

A biomechanical comparative analysis of two techniques for tibiotalar arthrodesis.

Two commonly used techniques for tibiotalar fusion were quantitatively compared using instrumented testing of the strength of the construct. The tibiae and tali from 10 pairs of fresh-frozen cadaveric limbs were used. One joint of each pair was fused using two 6.5-mm crossed cancellous screws from proximal to distal while the contralateral joint was fused using two 6.5-mm parallel cancellous screws from distal to proximal. Each specimen was subjected to cantilever bending and torsional testing by servohydraulic actuators. The bending tests included plantarflexion, dorsiflexion, inversion, and eversion, and measured the load during deflection applied 10 cm distal to the fusion site. The rigidity was expressed as newtons per millimeter of deflection. The torsional tests measured construct stiffness in external and internal rotation, and were expressed as newton-meters per degree of rotation. For the bending tests, the crossed screw construct was more rigid in eversion (23.1 N/mm, P = .0004) and dorsiflexion (16.9 N/mm, P = .02), while the parallel screw construct was more rigid in inversion (22.8 N/mm, P = .02) and plantarflexion (22.3 N/mm, P = .0007). In torsional testing, the crossed screw construct was at least 1.5 times stiffer than the parallel screw construct in resisting internal (1.7 N-m/deg versus 0.9 N-m/deg, P = .0001) and external (1.4 N-m/deg versus 0.9 N-m/deg, P = .02) rotation. In laboratory testing, the crossed screw technique is more rigid than the parallel screws, especially in resisting torsional stresses.(ABSTRACT TRUNCATED AT 250 WORDS)

Ankle Joint↗
PubMed1994

Topographical anatomy of the intercondylar roof. A pilot study.

Anatomical features of the intercondylar roof with respect to the native anterior cruciate ligament and proposed substitute ligament attachment sites in anterior cruciate ligament reconstructive surgery were investigated. Using cadaveric knees and K wires, radiographs were obtained with markers placed on the roof and the tibial and femoral attachment sites. In the knees studied, the intercondylar roof was V shaped with distinct anterior and posterior limbs. The posterior limb corresponded to the radiographic line commonly called Blumensaat's line. The anterior limb was oriented 25 degrees more vertical than the posterior limb and impinged on the anterior cruciate ligament in extension. In this pilot study, estimates of the degree of impingement in full extension were made by drawing lines representative of 10-mm grafts at selected sites on lateral radiographs. A graft placed at the central portion of the native femoral site to the normal tibial site did not impinge, while a graft placed at the traditional femoral site to an anteromedial tibial site impinged as much as 8 mm throughout its entire extent. This pilot study presents preliminary, provocative information suggesting that the intercondylar roof is actually V shaped and that substitute ligaments placed at attachment sites commonly used today may impinge over most of their length.

Anterior Cruciate Ligament↗
PubMed1993

Cloning and characterization of btr, a Bordetella pertussis gene encoding an FNR-like transcriptional regulator.

To determine whether hemolytic factors other than the bifunctional hemolysin-adenylate cyclase toxin (cyclolysin) are expressed by Bordetella pertussis, a gene library was constructed from a virulent strain of B. pertussis, BP504, transformed into nonhemolytic Escherichia coli, and screened on blood agar plates. A strongly hemolytic colony which contained the plasmid pHLY1A was isolated. Nucleotide sequencing of pHLY1A revealed an open reading frame that could encode a 27-kDa protein. No similarity was detected between the deduced amino acid sequence of this open reading frame and those of any known bacterial cytolysins. However, significant homology was detected with FNR of E. coli and several other transcriptional regulators including HylX from Actinobacillus pleuropneumoniae, which can also confer a hemolytic phenotype on E. coli. An fnr mutant of E. coli, JRG1728, could be complemented by pHLY1A. Thus, the B. pertussis transcriptional regulator-like gene and the protein which it encoded were named btr and BTR, respectively. A BTR-deficient B. pertussis strain, BJB1, was constructed. The btr::kan mutation had no effect on the expression of hemolytic activity or on phase variation. Northern (RNA) blotting revealed that btr expression was not regulated by the BvgAS two-component sensor-regulator. On the basis of sequence similarity to FNR-like transcriptional regulators and the ability to complement an anaerobically deficient E. coli strain (JRG1728) in growing anaerobically, BTR may regulate B. pertussis gene expression in response to changes in oxygen levels or to changes in the redox potential of the bacterial environment. Its role in virulence remains to be determined.

Actinobacillus pleuropneumoniae↗
PubMed1992

Uptake and intracellular survival of Bordetella pertussis in human macrophages.

Recent reports have demonstrated that Bordetella pertussis has invasive behavior in vivo and in vitro. In this study, we investigated the ability of a virulent strain, avirulent mutants, and mutants deficient in specific virulence factors to enter and survive intracellularly in human macrophages in vitro. Uptake of virulent B. pertussis was dose dependent and occurred in the absence of serum or specific antibody, with entry occurring via a microfilament-dependent phagocytic process. The virulent wild-type parental strain was internalized and persisted intracellularly over the 3 days of experiments, as determined by transmission electron microscopy and by recovery of viable plate counts. This is the first report of long-term survival of B. pertussis in human macrophages. Avirulent mutants entered macrophages, but at only an average of 1.5% of virulent parental levels, and did not survive intracellularly. Mutants which did not express adenylate cyclase toxin, filamentous hemagglutinin, or pertussis toxin had decreased abilities to enter and to survive inside macrophages. The results suggest that the internalization process, as well as intracellular survival, is virulence dependent and that mutations which inactivate expression of virulence factors may affect both. The ability of B. pertussis to enter and persist inside macrophages may be important not only for survival of the bacteria but also in the pathogenesis of whooping cough.

Bordetella pertussis↗
PubMed1992

Bordetella pertussis induces respiratory burst activity in human polymorphonuclear leukocytes.

Virulent Bordetella pertussis strains survive intracellularly within human polymorphonuclear leukocytes (PMN), at least in part because of inhibition of phagosome-lysosome fusion (L. L. Steed, M. Setareh, and R. L. Friedman, J. Leukocyte Biol. 50:321-330, 1991). Further investigations were done to determine if B. pertussis also inhibited respiratory burst activity of PMN as an additional mechanism of intracellular survival. Chemiluminescence and flow cytometry assays showed that B. pertussis induced significant levels of hydrogen peroxide production. In contrast, ferricytochrome c reduction showed that B. pertussis suppressed extracellular release of superoxide. PMN intracellular reduction of nitroblue tetrazolium verified that superoxide was indeed produced intracellularly during B. pertussis phagocytosis. Therefore, B. pertussis does not inhibit production of superoxide but inhibits only its release. Thus, while phagosome-lysosome fusion is inhibited by B. pertussis, respiratory burst activity of PMN occurs at normal levels.

Bordetella pertussis↗
PubMed1991

Intracellular survival of virulent Bordetella pertussis in human polymorphonuclear leukocytes.

Little is known regarding the interaction of Bordetella pertussis with polymorphonuclear leukocytes (PMNL) or the role PMNL play as an initial line of defense against B. pertussis infection. An in vitro system was developed to establish conditions for the study of phagocytosis and killing of virulent B. pertussis by human PMNL. Phagocytosis of B. pertussis strains BP504, BP165, and BP338 occurred by opsonization with anti-B. pertussis antibody, while autologous normal human sera did not induce significant phagocytosis. In PMNL bacterial killing assays virulent B. pertussis strains survived PMNL bactericidal activities while Escherichia coli controls were readily killed. Electron microscopy studies using acid phosphatase as a lysosomal marker strongly suggested that B. pertussis inhibits phagosome-lysosome fusion in PMNL. These results indicate that virulent B. pertussis strains are capable of surviving intracellularly within PMNL and that such survival may be due to inhibition of phagosome-lysosome fusion.

Antibodies, Bacterial↗
PubMed1990

Effect of low-dose oral contraceptives on carbohydrate and lipid metabolism in women with recent gestational diabetes: results of a controlled, randomized, prospective study.

Women with recent gestational diabetes mellitus were randomly assigned to one of two low-dose oral contraceptives to evaluate the effect of low-dose oral contraceptives on carbohydrate and lipid metabolism. A cohort of similar women requesting a non-oral-contraceptive method served as controls. The two oral contraceptives studied were ethinyl estradiol (0.035 mg)-norethindrone (0.40 mg) and ethinyl estradiol (0.030 to 0.040 mg)-levonorgestrel (0.050 to 0.125 mg). A 75 gm, 2-hour oral glucose tolerance test and a fasting lipid profile (total cholesterol, triglyceride, high- and low-density lipoprotein cholesterols) were performed at entry, after 3 months, and after 6 to 13 months of treatment. The prevalence of diabetes at 6 to 13 months (27/156 patients) was not significantly different between groups (non-oral-contraceptive group, 17%; ethinyl estradiol-norethindrone, 15%; ethinyl estradiol-levonorgestrel, 20%). When examined by prior gestational diabetes mellitus class, diabetes mellitus was present in 7% of prior class A1 and 29% of women with prior class A2 disease (p less than 0.001). Mean cholesterol and low-density lipoprotein cholesterol levels were significantly improved in all three groups at 3 months and at 6 to 13 months, whereas triglycerides remained unchanged. There were no differences in cholesterol, low-density lipoprotein cholesterol, or triglycerides levels between the groups. After 6 to 13 months, there was a significant increase in high-density lipoprotein cholesterol in the ethinyl estradiol-norethindrone group compared with the ethinyl estradiol-levonorgestrel and non-oral-contraceptive groups.

Adult↗
PubMed1990

Effects of pertussis toxin on vasodilation and cyclic GMP in bovine mesenteric arteries and demonstration of a 40 kD soluble protein ribosylation substrate for pertussis toxin.

The inhibitory nucleotide-regulatory protein (Gl) has been shown to lose its adenylate cyclase inhibitory effect upon treatment with pertussis toxin. To find out whether a pertussis sensitive mechanism is involved in the regulation of the cGMP-system, bovine mesenteric arteries were incubated in buffer containing pertussis toxin, and the relaxation and intracellular cGMP accumulation induced by different groups of vasodilating agents were studied. The present results show a pertussis toxin induced decrease in relaxation as well as a decrease in the cGMP-elevation induced by the endothelium dependent vasodilators acetylcholine and calcium ionophore A 23187. Arteries treated with atrial natriuretic peptide showed no alterations in relaxation or cGMP content after incubation with pertussis toxin. A 40 kD soluble ribosylation substrate for pertussis toxin was identified in bovine mesenteric artery. These results suggest that a pertussis toxin sensitive mechanism is involved in the vasodilating mechanism of acetylcholine and calcium ionophore A 23187, while no evidence for such a mechanism could be found regarding the vasodilatory action of atrial natriuretic peptide.

Acetylcholine↗