Isolation of picomolar affinity anti-c-erbB-2 single-chain Fv by molecular evolution of the complementarity determining regions in the center of the antibody binding site

We determined the extent to which additional binding energy could be achieved by diversifying the complementarity determining regions (CDRs) located in the center of the antibody combining site of C6.5, a human single-chain Fv (scFv) isolated from a non-immune phage library which binds the tumor antigen c-erbB-2. CDR3 of the light (V(L)) and heavy (V(H)) chain variable region of C6.5 were sequentially mutated, the mutant scFv displayed on phage, and higher affinity mutants selected on antigen. Mutation of V(L) CDR3 yielded a scFv (C6ML3-9) with a 16-fold lower Kd (1.0 x 10(-9) M) than C6.5. Due to its length of 20 amino acids, four V(H) CDR3 libraries of C6ML3-9 were constructed. The greatest increase in affinity from a single library was ninefold (Kd = 1.1 x 10(-10) M). Combination of mutations isolated from separate V(H) CDR3 libraries yielded additional ninefold decreases in Kd, resulting in a scFv with a 1230-fold increase in affinity from wild-type C6.5 (Kd = 1.3 x 10(-11) M). The increase in affinity, and its absolute value, are comparable to the largest values observed for antibody affinity maturation in vivo or in vitro and indicate that mutation of V(L) and V(H) CDR3 may be a particularly efficient means to increase antibody affinity. This result, combined with the location of amino acid conservation and substitution, suggests an overall strategy for in vitro antibody affinity maturation. In addition, the affinities and binding kinetics of the single-chain Fv provide reagents with potential tumor targeting abilities not previously available.

Pathologic fracture of the mandible caused by intraosseous metastasis of oesophageal squamous cell carcinoma: a case report

A rare case of oesophageal squamous cell carcinoma metastasizing to the mandible and causing a pathologic fracture is described. The relevant literature is reviewed.

Intensive care unit stay is prolonged in chronic alcoholic men following tumor resection of the upper digestive tract

BACKGROUND

The prevalence of chronic alcohol misuse in patients with oral, pharyngeal, laryngeal or esophageal carcinomas exceeds 60%. No data is available, to our knowledge, on the morbidity and mortality of chronic alcoholics in surgical intensive care units (ICU) following tumor resection. We investigated whether the subsequent ICU stay in chronic alcoholics following tumor resection was prolonged and whether the incidence of pneumonia and sepsis was increased.

METHODS

213 patients with carcinomas of the upper digestive tract were evaluated regarding their drinking habits. Chronic alcoholics met either the DSM-III-R criteria for alcohol abuse or dependence. Conventional laboratory markers and serum carbohydrate-deficient transferrin were determined preoperatively. Major intercurrent complications during ICU stay such as an alcohol withdrawal syndrome, pneumonia and sepsis as well as the frequency of death were documented.

RESULTS

Patients did not differ significantly between groups regarding age or APACHE score on admission to the ICU.121 patients were diagnosed as being chronic alcoholics, 39 as being social drinkers and 61 as being non-alcoholics. In chronic alcoholics the frequency of death was significantly increased. Due to the increased incidence of pneumonia and sepsis the ICU stay was significantly prolonged in chronic alcoholics by approximately 8 days.

CONCLUSIONS

The increased mortality and morbidity rate demonstrates that chronic alcoholics undergoing major tumor surgery have to be considered as high-risk patients during their postoperative ICU stay. Further studies are required with respect to the immuno-competence of chronic alcoholics and the prevention of alcohol withdrawal syndrome, pneumonia and sepsis in these patients.

Comparison of azathioprine, methotrexate, and the combination of the two in the treatment of rheumatoid arthritis. A forty-eight-week controlled clinical trial with radiologic outcome assessment

OBJECTIVE

To assess the relative efficacy of methotrexate (MTX), azathioprine (AZA), and their combination in the treatment of rheumatoid arthritis (RA) in a double-blind, prospective, multicenter, controlled trial.

METHODS

Two hundred nine patients with active RA were treated with escalating doses of MTX (5-15 mg/week), AZA (50-150 mg/day), or combination (5mg MTX/week plus 50 mg AZA/day-7.5 mg MTX/week plus 100 mg AZA/day), with opportunity to increase the dosage at 6-week intervals. The patients were evaluated for significant clinical and laboratory improvement and assessed for radiologic progression at 48 weeks.

RESULTS

One hundred ten patients remained on the initial, randomly assigned therapeutic regimen. The percentage of patients who were responders, defined as those who had 30% or greater improvement in at least 3 of 4 variables, was 38% for the combination treatment, 26% for AZA, and 45% for MTX (P = 0.06). A trend toward decreased radiologic progression was seen in the MTX-treated patients. Termination of treatment due to adverse experience occurred more frequently with combination and AZA treatments than with MTX treatment. Lack of effectiveness, adverse gastrointestinal effects, and liver enzyme elevation were the most frequent causes of treatment discontinuation.

CONCLUSION

This study establishes that the combination of MTX and AZA in the dosages utilized is not associated with more toxicity than treatment with single agents; however, enhanced efficacy is also not seen. There is a trend toward decreased radiologic progression in patients treated with MTX.

Beta-carbolines in chronic alcoholics undergoing elective tumor resection

The prevalence of chronic alcoholism in patients with carcinomas of the upper digestive tract exceeds 60%. The patient's history and laboratory markers, preoperatively, are often not sensitive or specific enough to detect alcohol-dependent patients, preoperatively, who are at risk of developing alcohol withdrawal syndrome (AWS) during their postoperative intensive care unit (ICU) stay. Previously, it was found that plasma norharman was elevated in chronic alcoholics, suggesting marker characteristics for chronic ethanol misuse and possibly alcohol dependence. We investigated whether beta-carbolines (i.e., harman and norharman) were different between chronic alcoholics and nonalcoholics with carcinoma, and how the levels change in alcohol-dependent patients during their hospital stay. Ninety-seven patients with oral, pharyngeal, laryngeal, or esophageal carcinomas were evaluated regarding their drinking habits. Sixty patients were transferred to the ICU following tumor resection. Chronic alcoholics met the DSM-III-R and ICD-10 criteria for alcohol dependence or chronic alcohol abuse/harmful use. The daily ethanol intake in chronic alcoholics was > or = 60 g. Blood samples were collected on admission to the hospital, preoperatively, on admission to the ICU and on days 2, 4, and 7 in the ICU. Harman and norharman were determined by HPLC. Elevated norharman was found in chronic alcoholics on admission to the hospital, whereas harman did not differ between groups. On admission, the area under the receiver operating characteristics curve was significantly larger for carbohydrate-deficient transferrin and preoperatively for norharman. The preoperative norharman levels were significantly correlated with the period of mechanical ventilation and the length of ICU stay. Postoperatively, norharman decreased in all patients, except a group of 11 alcohol-dependent patients who developed AWS during their ICU stay. The finding that elevated norharman levels were found in chronic alcoholics on admission to the hospital and preoperatively supports the view of a specific marker for alcoholism. Preoperative norharman was superior to carbohydrate-deficient transferrin and was associated with a prolonged ICU stay and a prolonged period of mechanical ventilation. Further studies are required to determine whether norharman aids in the preoperative diagnosis of chronic alcohol misuse with respect to the prevention of postoperative complications.

Informal out-patient discussions with patients following surgery for large bowel cancer: are they beneficial?

The value of informal out-patient discussions as a useful, additional method of assessment for both patient and doctor during a busy out-patient clinic is considered. One hundred patients were interviewed by a research or stoma care sister at their first follow-up visit after surgery for large bowel cancer in the combined Oncology/Surgical out-patient clinic of a district general hospital. Particular interest was taken of patients' awareness of diagnosis (85% understood) and operation (93% understood), general well-being (74% had resumed limited activity), dependency on the primary health care team (13%), family history of bowel or associated cancers (as many as 31% had one or more first degree relatives affected) and the suitability for research trials, including adjuvant radiotherapy/chemotherapy (29% were entered). Patients appreciated the opportunity to discuss problems at a particularly stressful period of their lives. It would seem that when problems are identified and an overall assessment of patients' needs made, relevant information is provided for doctors which is influential in improving patient care.

Pattern of arterial aneurysms in acquired immunodeficiency disease

The ever-spreading incidence of infection with the human immunodeficiency virus (HIV) has introduced a spectrum of unusual, subtle, and often life-threatening lesions that can affect almost every organ and tissue in the body. With the introduction of laboratory serologic evidence of HIV infection, the spectrum of indicator diseases has extended beyond the classic opportunistic infections and Kaposi sarcoma. An analysis of 28 patients in Zimbabwe with focal areas of vascular disease treated during a 4-year period (1989-1993) defined 16 patients ranging in age from 12 to 46 years appropriate for special scrutiny as they evinced none of the usual causes of vascular disease. Twelve of the patients were HIV-positive; in two patients the serologic status was unknown; and two patients were HIV-negative at the time of their presentation. There were special clinical features in this group of patients selected for study: (1) They were young with a mean age of 31 years; (2) they were all indigenous Africans with no evidence of atherosclerosis; and there was (3) rapid development of focal necrotizing vasculitis with aneurysm formation and rupture or (4) slow, progressive development of granulomatous vasculitis. The sites of cardiovascular involvement included the left ventricle; aortic arch; thoracic, thoracoabdominal, and abdominal aorta; and iliac, femoral, gluteal, popliteal, and subclavian arteries. It is inferred that the association between HIV-positive status and arterial aneurysms or fibroproliferative aortic occlusion are causally related and that the principles of vascular surgery can be successfully applied to their treatment.

Management of cardiovascular disorder in Zimbabwe: 1989-1992

The challenging task of establishing a cardiothoracic unit with open-heart surgical capability in a third-world setting emphasised the clinical need for such a facility but underscored the economic and logistic difficulties hampering its successful implementation. The common occurrence of advanced rheumatic valvular disease and the inordinately high incidence of congenital cardiac disorder in the indigenous Zimbabwean population mandates a need for their successful surgical management. The progressive maturation and dynamism of an established cardiothoracic unit necessarily requires it to pay attention to patient needs, to provision of an on-going educational programme at all staff levels and to the promotion of a relevant research policy.

Reliability and within subject variability of VE, VO2, heart rate and blood pressure during submaximum cycle ergometry

To assess the reliability and within subject variability of steady-rate ventilation (VE), oxygen uptake (VO2), heart rate, systolic and diastolic blood pressure, 4 subjects exercised for 10 minutes at 3 work rates on a bicycle ergometer: 50 W, 125 W and 55% of maximum work rate (55% max). Each testing session included two work rates and only 2 testing sessions were scheduled per week. The order of the work rates was counterbalanced. In 8 to 10 weeks, 3 of the subjects completed 20 trials at 50 W while the fourth subject completed 11 trials, and all the subjects completed 10 trials at 125 W and 55% max. The within subject variability (S2w) was expressed as a percent of the mean steady-rate response. VO2 ranged from 21.2% to 27.5% of VO2max at 50 W, from 37.7% to 49.7% at 125 W and from 42.9% to 63.7% at 55% max. The S2w averaged 6.8% for VE, 4.3% for VO2, 3.2% for heart rate, 7.3% for systolic blood pressure and 10.5% for diastolic blood pressure. Reliability coefficients were calculated for the steady-rate scores by dividing the between subject variation by the total variation. The reliability was similar for VE, VO2 and heart rate and ranged from r = 0.69 to r = 0.97. Systolic and diastolic blood pressure reliabilities were lower and ranged from r = 0.27 and r = 0.80. In summary, the steady-rate ventilation, oxygen uptake and heart rate responses were reliable and consistent. The reliability of blood pressure was low. It is possible that this low reliability may result from variability in stroke volume or total peripheral resistance.

Intestinal fatty acid binding protein in serum and urine reflects early ischemic injury to the small bowel

BACKGROUND

Intestinal fatty acid binding protein (I-FABP) is a 15 kd protein that constitutes 2% to 3% of enterocyte protein. Normally I-FABP is undetectable in serum. The purpose of this study was to determine whether I-FABP could be detected in peripheral serum and/or urine early in the evolution of intestinal ischemic injury.

METHODS

I-FABP and two putative biochemical markers of mesenteric ischemia, hexosaminidase and lactate dehydrogenase, were quantitated in the serum of rats subjected to mesenteric ischemia produced by: (1) 0.5 hours, 1 hour, or 3 hours of superior mesenteric artery (SMA) occlusion followed by reperfusion; (2) 1 hour of mesenteric occlusion to a 10 cm segment of jejunum followed by reperfusion; and (3) arterial ligation to a 10 cm segment of jejunum without reperfusion. I-FABP was also quantitated in the urine and intestinal mucosa of these animals.

RESULTS

The baseline serum I-FABP level was < or = 4.0 ng/ml in all animals. In control animals, I-FABP remained unchanged throughout the experiment. In the ischemia/reperfusion groups, I-FABP immediately appeared in the serum on reperfusion. With segmental arterial ligation, I-FABP was detected in the serum within 15 minutes. Urinary content of I-FABP rose 60 minutes after its initial appearance in the serum, and its elimination paralleled serum I-FABP levels. Serum hexosaminidase and lactate dehydrogenase levels only rose after 3 hours of SMA occlusion with reperfusion. One hour of SMA occlusion and reperfusion resulted in only mild to moderate mucosal injury, whereas 3 hours of SMA ischemia with reperfusion produced areas of transmural necrosis.

CONCLUSIONS

I-FABP is released into the peripheral circulation after reversible intestinal ischemic injury and has potential as a biochemical marker to facilitate the early detection of mesenteric ischemia.

A three-year experience with serum anodal trypsinogen as a biochemical marker for rejection in pancreatic allografts. False positives, tissue biopsy, comparison with other markers, and diagnostic strategies

Serum values of immunoreactive anodal trypsinogen (sAT) have been claimed to correlate well with rejection occurring in pancreatic allografts. We have studied the behavior of sAT in serial serum samples obtained from 39 type I diabetics undergoing whole-organ pancreas transplantation during the past 3 years. Patients had either received a pancreatic allograft simultaneously with a transplanted kidney (SPK, n = 33) or after a previous kidney transplant (pancreas after kidney [PAK] n = 6). The behavior of sAT was studied in relation to the clinical diagnosis of rejection. Graft amylase output for all 39 patients and serum creatinine for the 33 SPK recipients were also studied. Tissue biopsies were obtained from 11 patients with elevated sAT values and a presumptive diagnosis of rejection. Nine of these patients had SPK grafts and simultaneously elevated creatinine values. Tissue was obtained from the simultaneously transplanted kidney; all specimens revealed rejection. Two of the 11 patients had PAK allografts. Biopsies performed on the graft duodenum were consistent with acute rejection. Three additional patients with unchanged sAT values had biopsies for other reasons; these biopsies failed to demonstrate signs of acute rejection. Thus graft biopsy correlated exactly with sAT behavior in every case in which rejection was suspected. Five patients had elevations of sAT not associated with rejection: one resulted from direct trauma, two had outlet obstruction, and two had clinical diagnoses of graft pancreatitis. The sAT was more sensitive and specific than GAO and as sensitive as creatinine for SPK recipients. These studies confirm that sAT is a reliable, graft-specific biochemical marker for the early diagnosis of pancreatic rejection. The use of sAT should allow for the proper timing of graft biopsies and the judicious use of immunosuppressive agents, which will result in increased allograft survival for PAK and pancreas-alone allografts.

Physiologic responses to recumbent versus upright cycle ergometry, and implications for exercise prescription in patients with coronary artery disease

To clarify the influence of body position on exercise prescription, 14 men (mean age +/- standard deviation 60.0 +/- 6.1 years) with coronary artery disease who underwent randomized recumbent and upright cycle ergometer tests to volitional fatigue were studied. At 100 watts, heart rate (HR), systolic blood pressure, oxygen consumption (VO2), rate pressure product and rating of perceived exertion were greater (p less than 0.05) in the upright than in the recumbent position. At peak exercise, however, these variables were not significantly different. Regressions of relative HR versus VO2 for recumbent and upright cycle ergometry were comparable: y = 1.24x - 32.7 and y = 1.26x - 31.5, respectively, where y = % maximal VO2, and x = % maximal HR. These findings indicate that recumbent exercise prescriptions may be based on the peak HR and VO2 values obtained during upright cycle ergometry, and vice versa. However, differences in the cardiorespiratory responses at submaximal exercise preclude the interchangeability of upright and recumbent training work rates.

The immunochemical distribution of cyclophilin in normal mammalian tissues

Cyclophilin, a 17 Kd proline cis-trans isomerase, high-affinity (Kd 10(-8) M) target for the immunosuppressive drug cyclosporine has ubiquitous phylogenic distribution, but its tissue localization in mammals has not been detailed. To explore a potential relationship between the multiple systemic effects of CsA and the cellular and tissue distribution of CYP, thirty-three different normal porcine tissues were examined using an immunohistochemical technique. Tissue was obtained from farmbred pigs, immediately fixed in buffered formalin, and prepared as embedded 5-mu sections. Immune-specific staining was accomplished using an ABC immunoperoxidase method and an affinity-purified, monospecific, rabbit anti-CYP IgG. Cut sections served as their own blanks and controls, and all tissues were stained in batch to minimize the effects of variation in technique. Consistent with earlier reports, CYP was present in all tissues studied, however, there was remarkable heterogeneity in CYP distribution. Renal parenchymal cells, cardiac and striated muscle, pulmonary and skin demonstrated cytoplasmic immunospecific CYP--however, the cellular localization varied. Cytoplasmic staining of endothelial, neural, and glandular elements was consistently observed. Contrasting with previous reports, CYP localized to the nucleus as well as the cytoplasm of some lymphoid cells, hepatocytes, and cells of the large intestine. Generally, greater CYP-specific staining was noted in organs amenable to CsA immunosuppression (heart, liver, kidney), compared with organs deemed more immunologically vulnerable when allografted under CsA (pancreas, lung, small bowel). Similarly, CYP-immunospecific staining was abundant in tissues susceptible to CsA toxicities (neural tissue, smooth muscle, kidney, liver). This detailed immunohistological examination affords a correlation between CYP content and sensitivity to CsA. It also raises some new questions about tissues with little extractable CYP but significant histological staining.

Gender dimorphism in size, shape and body composition of child-onset obese and nonobese adolescents

Gender dimorphism (percent GD) for stature (S), body size, body mass (BM) distribution and body composition for obese and nonobese male and female adolescents (mean age 12.7 years, range 10.5-14.5) was compared for 22 girths, 13 bony widths, five skin + fat folds (SF), fat mass (FM), fat free mass (FFM), body density (Db), and calculated variables (BMI, BSA, unit-size mass, waist:hip ratio (WHR), and FFM/S). BM distribution was computed with the ponderal mass equivalent somatogram. There was significant (P less than or equal to 0.05) percent GD for FM, FFM, Db, for the nonobese, but not obese. Only the neck, forearm and wrist girths revealed small but significant (P less than or equal to 0.05) percent GD for the obese. There was no girth percent GD for the nonobese. The elbow, wrist and ankle diameters revealed significant (P less than or equal to 0.05) percent GD for the obese; there was no significant percent GD for the nonobese for the same bony widths. Only the subscapula and iliac SF revealed significant (P less than or equal to 0.05) percent GD for the obese. For nonobese, percent GD was significant (P less than or equal to 0.05) for the triceps, subscapula and thigh SF, Comparisons between obese and nonobese indicated significant (P less than or equal to 0.05) differences between obese and nonobese males and females for FM, FFM, all girths and SF, but not S. Surprisingly, the obese and nonobese had nearly identical trunk diameters; the sum of biacromion, chest, biilac, and bitrochanter diameters were different by only 4.6 percent (n.s.) for the obese and nonobese males, and 1.3 percent (n.s.) for the obese and nonobese females. Thus, a large central frame-size cannot be used to justify the acquisition or maintenance of a larger than average BM for the obese. The ponderal equivalent analyses revealed that the obese's abdomen was the size of a person projected to have a BM in excess of 100 kg. The use of surface anthropometry in the study of adolescent obesity was supported.

Gamma-carboxylated isoforms of recombinant human protein S with different biologic properties

Human protein S (HPS), a regulator of hemostasis, is a vitamin K-dependent plasma protein with potential clinical utility. We have obtained high-level expression of the cDNA for HPS in two mammalian cell lines. Both cell lines secreted single chain recombinant HPS (rHPS) in serum-free medium as determined by Western blot analysis. The ability of the rHPS from both cell lines to act as a cofactor for human protein C (HPC) was determined; the rHPS secreted from the human 293 cell line had an activity six times that of the rHPS from the AV12-664 Syrian hamster cell line. Furthermore, the relative specific cofactor activity of rHPS from the 293 cell line was actually 2.5-fold higher than that of single-chain human plasma-derived HPS. Essentially all of the rHPS secreted from the 293 cell line exhibited a calcium-dependent elution profile on anion exchange chromatography, whereas only 25% to 35% of the hamster cell-derived rHPS exhibited this profile. However, the calcium-eluted rHPS from the AV12 cell line had a high specific cofactor activity, equivalent to that of the 293-derived rHPS. A NaCl-elutable rHPS fraction (calcium nondependent) was isolated from the recombinant AV12-664 cell line, further purified, and found to have reduced activity, only 40% that of the calcium-dependent rHPS. The only observable difference in the calcium-dependent and nondependent rHPS molecules was in the content of gamma-carboxyglutamic acid (Gla); the calcium-dependent material contained approximately 10 mol Gla/mol protein whereas the calcium-nondependent material contained only approximately 8 mol Gla/mol of protein. In addition, the calcium-nondependent rHPS had reduced ability to interact with phospholipid vesicles as evidenced by an eightfold increase in the apparent kd. Our data demonstrate the isolation of rHPS with high specific activity, and show that a reduction in as few as two Gla residues dramatically decreases its functional cofactor activity for HPC, due to a reduction in ability to interact with the phospholipid bilayer.

Essentials of open heart surgery

As Parirenyatwa continues its successful OPEN-HEART SURGERY PROGRAMME, it becomes important to emphasize that the essential determinants for cardiac surgical success include a comprehensive preoperative assessment of the patient; accurate definition of the fundamental lesion; ameliorative treatment of secondary effects such as cardiac failure, electrolyte imbalance and arrhythmia. In addition to the application of technical expertise in the performance of the operation, an optimal outcome depends on good intraoperative anesthetic management, the collaboration of pump technicians, and dedicated intensive care management in the postoperative period.

The effects of ketanserin on ventricular ectopic activity in humans

Ketanserin is a serotonin S2-receptor antagonist that lowers blood pressure and inhibits platelet aggregation. Ketanserin treatment is also associated with prolongation of the corrected QT interval. The recently reported Prevention of Atherosclerotic Complications with Ketanserin (PACK) trial confirmed this prolongation of QT and also revealed a significant excess of deaths in patients receiving ketanserin together with potassium-losing diuretics. The investigators suggested that this excess of deaths may have been attributable to exacerbation of hypokalemia-induced ventricular arrhythmias by the repolarization-prolonging effect of ketanserin. However, drugs that prolong the QT interval may affect ventricular ectopic activity beneficially, and our study was designed to evaluate the effects of ketanserin on ventricular ectopic activity. Twenty patients (18 male, 2 female) aged 42-73 years were studied, each having at least 15 ventricular ectopic beats/hour. The study design was a double-blind, crossover comparison of ketanserin, 40 mg twice daily, and placebo, both given for 1 week. Ventricular ectopic activity was assessed by 48-hour Holter electrocardiogram (ECG) tapes at the end of each treatment period. Ketanserin treatment was associated with prolongation of repolarization, as reflected by the significant mean increases in both QT interval (+30 ms; p less than 0.001) and corrected QT interval (+20 ms; p less than 0.05). The mean overall degree of ventricular ectopic activity, as represented by a score based on the Lown classification, was significantly reduced (p less than 0.05). This was associated with a concordant improvement in the individual indices of ectopic activity. Our results show that ketanserin significantly suppressed ventricular ectopic activity in our normokalemic patients.(ABSTRACT TRUNCATED AT 250 WORDS)