Receptor surface models. 2. Application to quantitative structure-activity relationships studies

A new technique for using receptor surface models in quantitative structure-activity relationship (QSAR) analysis is described. Receptor surface models provide compact, quantitative descriptors which capture three-dimensional information about putative receptor/ligand interactions. Receptor surface models can be constructed quickly, which allows the construction of multiple plausible models; a variable selection technique such as genetic function approximation (GFA) can then be used to suggest which receptor surface models provide the most valuable descriptors for QSAR. Advantages of this approach are shown by applying it against two previously-published and well-studied QSAR data sets. Our results indicate that the approach can model data as effectively as established 3D-QSAR techniques.

Effects of oxygen on wound responses to growth factors: Kaposi's FGF, but not basic FGF stimulates repair in ischemic wounds

Kaposi's fibroblast growth factor (K-FGF, FGF-4) is a newer member of FGF family with uncharacterized wound healing properties. Basic fibroblast growth factor (bFGF, FGF-2) has been well studied and accelerates repair in normal and impaired wound healing models. K-FGF and bFGF are known to have similar biological effects in tissue culture, and both stimulate fibroblast and endothelial cell proliferation. The rabbit dermal ulcer model was used to examine the effects of bFGF and K-FGF under ischemic and nonischemic conditions. We found bFGF was ineffective in stimulating healing under ischemic conditions even at high doses (30 micrograms/wound). However, when the ischemic wounds were treated with bFGF (5 micrograms/wound) plus hyperbaric oxygen therapy, it was highly effective again as previously found under nonischemic conditions (P < 0.05). In contrast K-FGF stimulated repair in both nonischemic and ischemic wounds (P < 0.05). These results suggest that wound oxygen content differentially regulates responsiveness to bFGF and that K-FGF is biologically active in hypoxic wounds.

Nitric oxide inhibition in the treatment of the sepsis syndrome is detrimental to tissue oxygenation

The manifestations of the septic syndrome are thought to be mediated by cytokines through their role in the production of nitric oxide (NO). It is hypothesized that the inhibition of NO production with an inhibitor such as NG-monomethyl-L-arginine (L-NMMA) may be beneficial in the treatment of septic shock. Sepsis was induced by the intravenous administration of Escherichia coli endotoxin (60 micrograms/kg) in six conditioned mongrel dogs (20-24 kg). Mean arterial pressure (MAP), heart rate (HR), central venous pressure (CVP), and pulmonary artery pressure (PAP) were continuously monitored. Cardiac output (CO), pulmonary capillary wedge pressure (PCWP), and arterial and mixed venous blood gases were obtained every 10 min. When the MAP decreased below 60 mm Hg, NO inhibitor L-NMMA was given by intravenous injection (25 mg/kg). Physiologic parameters were then measured at 2 and 5 min after L-NMMA injection. Subsequently, L-arginine (400 mg/kg), the substrate for the NO synthase enzyme, was administered and measurements were repeated at similar intervals. L-NMMA in septic canines produced a significant increase in MAP and SVR with a significant decrease in CO and tissue oxygenation (DO2 and VO2). These changes were reversed with the administration of L-arginine. There were no significant differences in the PCWP, CVP, PAP, or HR throughout the entire study. These results suggest that the inhibition of NO production by L-NMMA in a septic model produces elevated MAP and SVR at the expense of tissue oxygenation. Thus, its use, as a principal means of therapy for the septic syndrome, may not be appropriate because of detrimental effects on tissue oxygenation.

Pain ameliorating effect of eye movement desensitization

This study explores the efficacy of eye movement desensitization and reprocessing (EMD/R) in the management of acute pain induced by hand exposures to ice water. Thirty participants were randomly assigned to one of the following interventions: (a) eye movement desensitization and reprocessing, (b) eye movement desensitization with music (EMD/M), and (c) control. The EMD/R participants focused on negative experiences associated with exposure to ice water, generated positive self-talk, and diverted their attention away from pain by focusing on a rapidly moving light on a monitor. The EMD with music group received eye movement desensitization coupled with preferred music. Repeated measures univariate and multivariate analysis of covariance was used to analyze the data. Results indicated that both procedures alleviated participants' pain to a similar degree and significantly more than the control, P < 0.05.

Unilateral renal artery revascularization can salvage renal function and terminate dialysis in selected patients with uremia

Revascularization of renal arteries to salvage glomerular function in patients with chronic renal failure is performed infrequently. However, during the past 12 months we have encountered three patients over 60 years of age known to have chronic renal failure who were on dialysis for 2 weeks, 3 weeks, and 2 months, respectively. All three patients were hypertensive, requiring between four and five antihypertensive medications. One patient was ventilator dependent in intractable cardiac failure with pulmonary artery systolic pressures ranging from 60 to 70 mm Hg. Standard biplanar arteriography revealed occlusion of the left renal artery with distal reconstitution in two patients and a 99% stenosis of the right renal artery in the remaining patient. The contralateral renal artery was totally occluded in two patients and diffusely stenotic in one. The recipient kidneys measured 8, 10, and 11 cm in length. Kidney function was assessed by renal scintigraphy and creatinine clearance. Two splenorenal bypasses and one hepatorenal bypass with 6 mm polytetrafluoroethylene graft were performed successfully. After surgery, renal function improved in all patients with two of three patients resuming normal function as evidenced by reduction of serum creatinine levels to 0.9 and 1.3 mg/dl. The third patient recovered to have a creatinine level of 3.2 mg/dl. All patients were discharged home within 1 month with a daily urine output greater than 1500 ml. At discharge, each patient required only two antihypertensive medications to control blood pressure. Duplex scanning 3, 6, and 12 months after surgery confirmed patency of all reconstructions.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of prophylactic main pancreatic duct stenting on the incidence of biliary endoscopic sphincterotomy-induced pancreatitis in high-risk patients

Pancreatitis is a common complication of endoscopic sphincterotomy. Cautery-induced papillary edema has been implicated as a possible cause. The objective of this study was to determine whether prophylactic stenting of the main pancreatic duct after endoscopic sphincterotomy in high-risk patients would reduce the incidence of pancreatitis. High-risk patients were defined as those with sphincter of Oddi dysfunction, small common bile duct diameter (< 10 mm), or those requiring pre-cut sphincterotomy. Patients were studied in a prospective fashion from October 1990 to April 1992 and were randomized to receive either a main pancreatic duct stent or no stent after biliary sphincterotomy. The stents were generally removed 10 to 14 days after placement. Fifty patients were randomized to the no-stent group and 48 patients were randomized to the stent group, but in five patients stent placement was unsuccessful. Pancreatitis occurred in 18% of patients in the no-stent group compared with 14% of patients in the stent group. Most cases of pancreatitis were mild, occurring in 10% of patients in the no-stent group and 12% of patients in the stent group. Moderate to severe pancreatitis occurred with an increased frequency in patients in the no-stent group (8%) compared with that in patients in the stent group (2%). Mean number of hospital days required to treat pancreatitis was 9.5 days in the no-stent group compared with 2.8 days in the stent group; however, none of these differences reached statistical significance. Small common bile duct diameter (< 6 mm) was found to be an independent risk factor for pancreatitis after endoscopic sphincterotomy.(ABSTRACT TRUNCATED AT 250 WORDS)

Localized but unresectable neuroblastoma: treatment and outcome of 145 cases. Italian Cooperative Group for Neuroblastoma

PURPOSE

To define factors that influence outcome in children with localized but unresectable neuroblastoma by retrospective investigation of response to therapy and outcome in 21 Italian institutions.

PATIENTS AND METHODS

Of 145 assessable children diagnosed between 1979 and 1990, 77 were treated between 1979 and 1984 with three consecutive standard-dose (SD) protocols, and 68 between 1985 and 1990 with a high-dose (HD) protocol. All protocols included chemotherapy, followed by resection of primary tumor if feasible. If at least partial resection was achieved, consolidation therapy followed, except that from 1985 onward, patients considered disease-free following surgery received no further treatment.

RESULTS

Ninety-four of 145 patients (65%) achieved a complete response (CR) or partial response (PR) with chemotherapy and 75 (52%) subsequently underwent complete resection of the primary tumor. Eighty-one patients are alive (73 without disease, eight with disease), 63 have died, and one is lost to follow-up. The 5-year overall survival (OS) rate is 55% and progression-free survival (PFS) rate 50%. Both OS and PFS correlated with response to chemotherapy, removal of primary tumor, HD therapy, and serum lactate dehydrogenase (LDH) levels. Infants (< 1 year), independent of primary tumor site, and children aged 1 to 15 years with a nonabdominal primary tumor, did better compared with children aged 1 to 15 years with an abdominal primary tumor (PFS, 72% and 64% v 30%; P < .001 and < .01, respectively). Outcome of this last group improved with the HD protocol (PFS, 40% v 23%; P = .01).

CONCLUSION

In children with unresectable neuroblastoma, risk categories can be defined by age and primary tumor site. HD chemotherapy should be investigated for the poor-risk category age 1 to 15 years with an abdominal primary tumor.

A biologically motivated associative memory architecture

A synthesis of analytical techniques from the fields of biology, mathematics, computer science and engineering are used to model the information processing characteristics of the mammalian cerebellar cortex. By viewing anatomically different neurons as representing network elements whose input-output functions are different, a mechanism for distributing information throughout the memory is proposed. The functional circuitry developed to implement this feature is called the microcircuit. Overlapping microcircuit activity is used to describe the memory's read and write operations. Key features of the memory model include: (1) its use of a sparse interconnection network, (2) its ability to manipulate very large input patterns, (3) its distributed storage of input data patterns and (4) its statistical reconstruction of stored patterns during memory read operations. Quantitative measures for the memory's recall fidelity and storage capacity are derived and results of computer simulations are presented.

Cleavage of K-FGF produces a truncated molecule with increased biological activity and receptor binding affinity

The K-FGF/HST (FGF-4) growth factor is a member of the FGF family which is efficiently secreted and contains a single N-linked glycosylation signal. To study the role of glycosylation in the secretion of K-FGF, we mutated the human K-fgf cDNA to eliminate the glycosylation signal and the mutated cDNA was cloned into a mammalian expression vector. Studies of immunoprecipitation from the conditioned medium of cells expressing this plasmid revealed that the lack of glycosylation did not impair secretion, however the unglycosylated protein was immediately cleaved into two NH2-terminally truncated peptides of 13 and 15 kD, which appeared to be more biologically active than the wild-type protein. These two proteins also showed higher heparin binding affinity than that of wt K-FGF. We have expressed in bacteria the larger of these two proteins (K140), in which the NH2-terminal 36 amino acids present in the mature form of K-FGF have been deleted. Mitogenicity assays on several cell lines showed that purified recombinant K140 had approximately five times higher biological activity than wild-type recombinant K-FGF. Studies of receptor binding showed that K140 had higher affinity than wt K-FGF for two of the four members of FGF receptor's family, specifically for FGFR-1 (flg) and FGFR-2 (bek). K140 also had increased heparin binding ability, but this property does not appear to be responsible for the increased affinity for FGF receptors. Thus removal of the NH2-terminal 36 amino acids from the mature K-FGF produces growth factor molecules with an altered conformation, resulting in higher heparin affinity, and more efficient binding to FGF receptors. Although it is not clear whether cleavage of K-FGF to generate K140 occurs in vivo, this could represent a novel mechanism of modulation of growth factor activity.

Survival after neonatal myocardial infarction

These are case reports of two children with structurally normal hearts and with normal coronary arteries, who survived myocardial infarction in the early neonatal period. They are only the third and fourth reported survivors of neonatal myocardial infarction and the first in which hypercholesterolemia is postulated to have played an important role. The most likely cause of the myocardial infarction was thrombosis or thromboembolism. Changes in hemostatic function associated with hypercholesterolemia may be relevant.

Myeloablative therapy and unpurged autologous bone marrow transplantation for poor-prognosis neuroblastoma: report of 34 cases

From October 1984 to November 1987, 34 patients aged from 1 year 1 month to 7 years 7 months with resistant or relapsed neuroblastoma (NB) (group 1, 10 patients), unselected disseminated NB (group 2, 14 patients), or selected disseminated NB (group 3, 10 patients) received myeloablative therapy (MAT) followed by unpurged autologous bone marrow transplantation (ABMT) at the end of an intensive protocol, which included high-dose chemotherapy and surgery to the primary tumor. Median time from diagnosis to MAT and ABMT was 6 months (5 months from last relapse to MAT and ABMT in the relapsed patients). The MAT regimen included vincristine, fractionated total body irradiation (TBI), and melphalan. Seventeen patients were grafted in complete remission (CR), five in very good partial remission (VGPR), 10 in partial remission (PR), and two in progressive disease (PD). The acute toxic death rate was 2.9%. The overall progression-free survival was 29%. The median progression-free survival was 20 months for the 17 patients grafted in CR, 6 months for the five patients grafted in VGPR, and 12 months for the 10 patients grafted in PR.