Discriminability of fracture and nonfracture cases based on the spatial distribution of spinal bone mineral

PURPOSE

The purpose of our study is to demonstrate that spinal mineral distribution measured with CT can distinguish normal from osteoporotic individuals.

METHOD

CT studies of lumbar vertebrae (L1-L3) from 121 clinically normal women without fractures and 57 women with one or more atraumatic fractures somewhere in the skeleton were evaluated with discriminant analysis based on indices of the spatial distribution and noise properties of spinal bone mineral density (BMD).

RESULTS

The use of discriminant analysis for all of the normal and osteoporotic women (L1-L3) resulted in a classification accuracy of 87.1% for fracture cases and 83.2% for nonfracture cases. In contrast, using the conventional method in the same patient population, 62.5% of BMD values of osteoporotics overlapped with those of normals whose BMD was below the 90th centile of osteoporotics.

CONCLUSIONS

CT-based measures of the spinal mineral distribution can increase the accuracy of discriminating fracture and nonfracture cases almost to 90% accuracy, even in a region below the fracture threshold. This shows that in this region the risk of fracture is not completely random but has a stochastic component as well.

The chasm: what can be done, and what should be done

The case study of growth hormone in short-stature children offers an example of the high cost of bioengineered therapies and the attendant ethical concerns. Despite uncertainties as to its efficacy, it is estimated that the annual U.S. expenditure for growth hormone, which costs about $20,000 per year for a 30 kg child, exceeds $375 million dollars. Ultimately, at this point in its evolution, the use of GH therapy illustrates the dilemma commonly created by new medical technology--the chasm between what can be done and what should be done. Unfortunately, the knowledge of what can be done precedes the understanding of what should be done.

Leukemia and/or myeloproliferative syndrome in neonates with Down syndrome

Approximately 10% of newborn infants with Down Syndrome develop a form of megakaryoblastic leukemia which usually disappears spontaneously during the first months of life. The evidence that this "Transient Leukemia" is truly leukemia includes the following: it is clonal proliferation, it can be fatal and tissue infiltration of leukemic cells occurs. Also in approximately 25% of cases that recover, Acute Megakaryoblastic Leukemia will develop in the first four years of life, which, if not treated, is fatal. Evidence regarding the megakaryoblastic nature of the leukemic cells is presented as well as a description of the lethal forms of the disease. The study of Transient Leukemia is of considerable importance because it can provide insight into both the nature of leukemia and its relation to trisomy 21.

Halfway technologies

An extraordinary gamut of medical and surgical therapies could be considered "halfway technologies," addressing mere symptoms or manifestations of disease, rather than the underlying pathogenesis. When a "halfway" technology is also lifesaving, its value cannot be underestimated by the individual patient. The example of organ transplantation explored in this column represents a halfway technology. It does not treat the underlying disease itself, but reflects the absolute failure of all efforts at medical and conservative therapy and is a last ditch, gerry-rigged lifesaving solution. And what about "quarter technologies"--the bridge to transplant devices--designed to get the patient halfway to the final halfway procedure?

Where the outside meets the inside: integrins as activators and targets of signal transduction cascades

In fibroblasts, signaling through the adhesion receptors known as integrins synergizes with other cellular stimulators such as the growth factors. There is currently great interest in the details of the ensuing 'outside in' signal transduction mechanisms, and the focal adhesion kinase in particular, has been a focus of attention. Less is understood of signalling through integrins on leukocytes which also perform a costimulator role. The activity of these leukocyte integrins is not constitutive but is initiated via signalling through other receptors, termed 'inside out' signalling. These signals cause movement and clustering of integrins in the membrane leading to strengthened adhesion between cells.

Panel discussion: impact of guidelines on third-party payors and HMOs

Utilization management (preauthorization) has given way to disease management, i.e., the management, by providers in cooperation with third-party payors, of patients and their disease states from beginning to end. Managed-care organizations are seeking guidelines-based cancer disease management programs that result in: lower, more predictable costs; authoritative quality assurance; measured outcomes; reduced preauthorization disputes; and improved management of cases in clinical trials. Guidelines also need to provide some consistency and consensus regarding the management of common clinical problems. Good guidelines help assist managed-care companies gather data, build a more solid utilization management foundation and support a clinically sound disease management program. Aetna's Institutes of Excellence (IOE) program seeks to address the issue of coverage for high-dose chemotherapy and bone marrow transplantation, but can serve as a useful model for the development of comprehensive cancer networks.

The ultimate goal? It depends

The knowledge that cervical cancer should be a preventable disease has provided the impetus to improve the Pap smear. Now, for the first time in 50 years, two new computerized technologies are available--the AutoPap and Papnet systems--that could change the way they are interpreted. Of course, these new innovations come at a price, perhaps doubling or tripling the cost--by one estimate, the new technologies could add $1 billion per year. The health policy issue is whether these innovations address the limitations of cervical cancer screening programs in an efficient way. The analysis is entirely different when cast as an individual patient care issue. Here the patient and physician, who serves as her advocate, want to use the best screening method. The goal is not how to best allocate resources to improve the health of the overall population, but instead how to get the best care for the individual patient.

Reversible parkinsonism and cognitive impairment with chronic valproate use

Following our initial report of the insidious development of reversible, valproate-induced hearing, motor, and cognitive dysfunction in two patients, we evaluated 36 patients in an epilepsy clinic who had been taking therapeutic levels of valproate for at least 12 months; 29 of these patients were examined according to a prospective protocol. We observed varying degrees of parkinsonism and cognitive impairment, from none to severe. Discontinuation of valproate in 32 affected patients led to subjective and objective improvement on follow-up testing at least 3 months later. Improvement was greatest in patients who were affected most. We conclude that a syndrome of reversible parkinsonism and cognitive impairment may develop insidiously in patients who have been treated with valproate for more than 12 months. The association with valproate may be overlooked due to the insidious onset.

Continuous peritoneal dialysis-associated peritonitis of nosocomial origin

OBJECTIVE

To describe our experience with nosocomial continuous peritoneal dialysis (CPD)-associated peritonitis focusing on the incidence, possible risk factors, spectrum of organisms, and outcome.

DESIGN

Retrospective review of the medical records of our CPD patients admitted to an acute-care hospital between November, 1993 and December, 1994.

SETTING

University-associated acute-care hospitals in New Haven, Connecticut.

PATIENTS

One hundred and eighty-eight patients maintained on CPD therapy and admitted to an acute-care hospital.

RESULTS

Nineteen patients (5%) developing nosocomial peritonitis (NP) were identified from the 408 admissions occurring during the study period. Patients developing NP were older than the hospitalized CPD patients not developing NP (65.5 +/- 14.6 vs 58.4 +/- 14.7 years, p < 0.05). Comorbid diseases including diabetes, peripheral vascular disease, gastrointestinal disease, cardiovascular disease, and human immunodeficiency virus seropositivity were not more common in the patients developing NP. Patients developing NP were hospitalized significantly longer than the CPD patients not developing NP (39.5 +/- 46.5 days vs 12.7 +/- 12.4 days, p < 0.001). The mean serum albumin was lower in the NP patients than in the CPD patients not developing NP (2.35 +/- 0.52 g/dL vs 3.02 +/- 0.60 g/L, p < 0.001). Antecedent antibiotic use and performance of invasive procedures were noted in 89% and 68% of the patients developing NP, respectively. Staphylococcal species, enterococcal species, and gram-negative organisms accounted for 26%, 21%, and 53% of the episodes of NP, respectively. Furthermore, two strains of Enterococcus resistant to vancomycin were cultured. Eight patients developing NP expired, 8 patients continued CPD therapy, 2 patients transferred to hemodialysis, and one patient recovered renal function.

CONCLUSION

We conclude that NP is uncommon. Increased age, increased length of hospital stay, and hypoalbuminemia may predispose patients to the development of NP. Further studies with case controls should help to clarify whether antecedent antibiotics or prior performance of invasive procedures predispose patients to the development of nosocomial peritonitis. The spectrum of organisms accounting for NP is different than the spectrum of organisms causing community-acquired CPD-associated peritonitis. Some of these organisms may be resistant to standard antibiotic therapies. Patients developing NP do poorly, with 42% expiring while being treated for NP.

Do splanchnic viscera contribute to liver preservation reperfusion injury?

Preservation-reperfusion injury of hepatic allografts is thought to be associated with Kupffer cell activation and TNF release from the transplanted organ. Confirmation that the allograft is the source of this TNF in an in vivo model is difficult because of rapid equilibration of this cytokine into all compartments. A novel experimental design was devised to aid in accurate localization of the site of TNF release following a orthotopic liver transplant (OLT). In the first group (anhepatic), livers were removed from rats and splanchnic and systemic venous returns were then reestablished using a conduit of donor IVC and portal vein with a portasystemic shunt. In the second group (asplanchnic), the liver, stomach, pancreas, and intestine of the recipient were removed and a donor liver was reimplanted using the recipient IVC as the source of portal blood. The third (OLT-16) and fourth (OLT 8) groups underwent standard OLT with preservation times of 16 and 8 hr in 4 degrees C Euro-Collins solution, respectively. TNF levels were significantly increased in the OLT-16 group compared with the OLT-8 group. There were modest elevations of TNF in the anhepatic model, but the TNF in the asplanchnic model approached baseline. Absence of TNF in the asplanchnic group and a rise in TNF levels in the anhepatic group to that not significantly different from OLT-16 or OLT-8 suggest that a major source of TNF following preservation reperfusion may be the intestine.

Delineation by use of specific monoclonal antibodies of the T-cell receptor and major histocompatibility complex interaction sites on the superantigen toxic shock syndrome toxin 1

Murine monoclonal antibodies (MAbs) specific for toxic shock syndrome toxin 1 (TSST-1), a bacterial superantigen, showed the ability either to detect TSST-1 bound to histocompatibility locus antigen (HLA)-DR molecules or to inhibit TSST-1 binding to HLA-DR. A MAb capable of detecting DR-bound TSST-1 could also inhibit the toxin-induced activation of a T-cell receptor Vbeta15-expressing murine T-cell hybridoma. Alternatively, MAbs with specificity for the HLA-DR association site could present TSST-1 in vitro, stimulating CD4+ human T cells to proliferate. These functional activities correlated directly with with MAb specificity for HLA-DR versus T-cell receptor Vbeta interaction sites on TSST-1 as determined by reactivity with a panel of recombinant TSST-1 mutant molecules. Therefore, these MAbs discriminate the superantigen functional sites on the TSST-1 molecule and constitute reagents with the property of being potent modulators of the toxic activity of TSST-1.

Optimally functional fluorescein isothiocyanate-labelled fibrinogen for quantitative studies of binding to activated platelets and platelet aggregation

Dynamic and quantitative studies of the binding of fibrinogen (Fg) to its receptor, GPIIb-IIIa, on activated platelets, leading to platelet aggregation, are best studied with fluorescently-labelled Fg by flow cytometry. Due to conflicting reports on the functionality of FITC-labelled Fg, we have developed a reproducible and 'mild' labelling of fibrinogen with FITC-celite at pH 7.4-8.5 for direct and dynamic studies of specific Fg binding to activated platelets evaluated for native platelet-rich plasma, for washed platelets, and for activated, fixed platelets. We have demonstrated the equivalence of FITC-labelled and unlabelled Fg for binding to activated GPIIb-IIIa receptors, and in the rate and extent of mediating platelet aggregation. We found that FITC-Fg labelled at pH > or = 9 had reduced to absent specific binding to activated platelets, whether using soluble FITC or FITC-celite. The FITC-labelled Fg must be diluted 3-fold with unlabelled Fg when evaluating maximal Fg binding to activated platelets in order to prevent autoquenching of the FITC-Fg which leads to underestimation of Fg levels. The dissociation constant (KD) of Fg on stable preparations of activated, fixed platelets, determined with FITC-Fg binding to platelets by flow cytometry, was in the range reported for 125I-labelled Fg, 70-255 nm with Bmax = 10000-25000 Fg per platelet (n = 20). The FITC-Fg was used to monitor Fg binding to activated platelets directly by plasma, as well as to evaluate platelet subpopulations which maximally bind Fg according to the concentration of ADP used as activator. It is expected that this 'mildly' labelled FITC-Fg will stimulate further studies of platelet activation directly in native anticoagulated blood/plasma, for both basic and clinical research.

Tumor chemosensitivity and chemoresistance assays

BACKGROUND

Chemosensitivity and chemoresistance assays have been used to select potentially more effective chemotherapy regimens and to avoid the toxicity of potentially ineffective drugs.

METHODS

Literature review was conducted.

RESULTS

The relevant outcome measure for chemosensitivity assays is improved patient survival. However, the relevant outcome measure for chemoresistance assays is more controversial. Advocates propose that the avoidance of the toxicity of potentially ineffective drugs is the relevant outcome, whereas others believe that the latter is an intermediate outcome and that improved patient survival is the appropriate outcome for both chemoresistance and chemosensitivity assays. There have been no clinical trials showing that either of these assays is associated with improved patient survival.

CONCLUSIONS

In terms of improved patient survival, the clinical role of chemosensitivity and chemoresistance assays is unproven. The use of the assays will vary depending on the type and stage of the tumor involved, the proposed role of chemotherapy, and the role of the empiric judgement of the physician.

Preventing malnutrition in patients on CAPD

Malnutrition is not uncommon in patients on CAPD. Thorough assessment and accurate records are essential for recognition of early indicators. Dietary advice can improve compliance. Intraperitoneal infusion of amino acids may be useful in some patients.