Cobalamin (vitamin B12) deficiency detection by urinary methylmalonic acid quantitation

A study was made to assess the value of cobalamin deficiency detection through quantitation of urinary methylmalonic acid (MMA). Urinary MMA was measured in 1118 patients suffering from megaloblastic anemia, other anemias, elevated red cell mean corpuscular volume, or unexplained neurologic disorders. Patients without proven cobalamin deficiency had urinary MMA levels less than 20 micrograms/ml. All patients (n = 27) confirmed to have cobalamin deficiency showed MMA levels greater than 20 micrograms/ml. Data are presented showing the Schilling test results, the comparison of serum cobalamin to urinary MMA levels, and other basic hematologic data. MMA levels are a good indication of cobalamin distribution and function since they are directly related to a cobalamin-dependent metabolic pathway. With rapid, reliable quantitation by mass spectrometry, urinary MMA can now be a useful clinical test.     

Effects of the cell adhesion peptide, Arg-Gly-Asp-Ser, on responses of washed platelets from humans, rabbits, and rats

Fibrinogen is a cofactor in the aggregation of human platelets, and is required for ADP-induced aggregation of washed platelets; however, exogenous fibrinogen is not required for ADP-induced aggregation of washed platelets from rabbits or rats. Because with human platelets the cell adhesion peptide, Arg-Gly-Asp-Ser (RGDS), inhibits aggregation and the binding of 125I-fibrinogen to ADP-stimulated platelets, its effects on rabbit and rat platelets were studied to investigate the differences in the fibrinogen requirements of platelets from the three species. RGDS (50 mumol/L) caused greater than 80% inhibition of thrombin- induced or (ADP + fibrinogen)-induced aggregation of human platelets, but only 3% to 9% inhibition of the aggregation of rabbit or rat platelets, regardless of whether fibrinogen was added. RGDS inhibited the binding of 125I-fibrinogen to ADP-stimulated human platelets by 80% to 90%, but by only 15% to 27% in the case of rabbit or rat platelets. The differences were due to the species of platelets, since human and rabbit fibrinogens gave similar results. In addition, RGDS failed to displace fibrinogen from the surface of rabbit platelets that had been stimulated with ADP. Thus, there are species differences in the ability of the cell adhesion peptide, RGDS, to block the platelet fibrinogen receptor, even within the mammalian species.     

Neutrophil elastase produces 52-kD and 30-kD glucocorticoid receptor fragments in the cytosol of human leukemia cells

Characterization of glucocorticoid receptors in leukemia cells is important to understand mechanisms of glucocorticoid resistance but has been impeded by receptor fragmentation in cytosol extracts. We recently found that formation of 52- and 30-kilodalton (kD) glucocorticoid receptor fragments in cytosol of leukemia cells is due to proteolysis and is blocked by diisopropylfluorophosphate (DFP). In the present study, we identify a 28-kD serine protease in cytosol of leukemia cells that binds [3H]DFP and correlates with the formation of 52- and 30-kD receptor fragments. This protease is immunoprecipitated by antiserum to neutrophil elastase. Limited digestion of [3H]dexamethasone-21-mesylate- labeled receptors by purified neutrophil elastase produces 52- and 30- kD receptor fragments. Receptor fragmentation in the cytosol of leukemia cells in inhibited by methoxysuccinyl-alanyl-alanyl-prolyl- valyl-chloromethylketone, a highly specific inhibitor of neutrophil elastase. The addition of as few as 5% neutrophils to a lymphoid cell suspension provides sufficient elastase to produce receptor fragmentation. Our findings indicate that neutrophil elastase is responsible for receptor fragmentation in the cytosol of leukemia cells. The neutrophil elastase may be endogenous to the leukemia cells or may come from neutrophils that contaminate leukemia cell suspensions.     

Platelet storage pool deficiency in pigs

We report a new bleeding disease--storage pool deficiency (SPD) of platelets--in pigs from the Mayo swine colony of homozygous von Willebrand's disease (vWD) and of heterozygous carriers of vWD. Levels of factor VIII, von Willebrand factor antigen (vWF:Ag), and ristocetin cofactor (RCof) were similar in the vWD carriers and SPD pigs. The latter pigs, however, had bleeding times of 15 minutes or more and were severe bleeders, in contrast to clinically normal vWD carriers. Platelet aggregation in response to collagen was reduced in most SPD pigs. Total platelet content of ADP, ATP, and serotonin was less than that of normal pigs. While the initial uptake of 14C-labeled serotonin into platelets was similar in SPD and normal pigs, retention of serotonin was reduced in platelets of SPD pigs. Transmission electron microscopy showed a large decrease of dense bodies in the platelets of SPD pigs. These findings support a diagnosis of SPD. Genetic analyses suggest an autosomal recessive mode of inheritance. A breeding program is under way to produce pigs affected only at the SPD gene, thus allowing further characterization of SPD and SPD-carrier pigs.     

Amifostine (WR-2721) shortens the engraftment period of 4- hydroperoxycyclophosphamide-purged bone marrow in breast cancer patients receiving high-dose chemotherapy with autologous bone marrow support

4-Hydroperoxycyclophosphamide (4-HC), a commonly used marrow-purging agent, is active against many tumors, but is also toxic to normal marrow progenitors. Amifostine (WR-2721) is a sulfhydryl compound with chemoprotectant activity. Preclinical studies using suspensions of bone marrow and breast cancer cells demonstrated that ex vivo treatment with amifostine followed by 4-HC resulted in protection of marrow progenitors, with no compromise in the antitumor effect of 4-HC. This fact stimulated the development of a clinical trial. Bone marrow was harvested from 15 poor-prognosis breast cancer patients and randomly assigned to ex vivo treatment with amifostine followed by 4-HC (amifostine + 4-HC), or treatment with 4-HC alone. High-dose chemotherapy was then administered followed by infusion of the purged autologous bone marrow support (ABMS). Leukocyte engraftment, defined as a white blood cell count > or = 1 x 10(9)/L, was achieved in an average of 26 days for patients whose marrow was purged with amifostine + 4-HC versus 36 days for patients whose marrow was purged with 4-HC alone (P = .032). The average number of platelet transfusions (12 v 29; P = .017) and days of antibiotic therapy (28 v 40; P = .012) were significantly less for patients whose marrow was exposed to amifostine + 4-HC, compared with 4-HC alone. Unpurged backup marrow fractions were infused into three patients whose marrow was purged with 4-HC alone, because of inadequate marrow recovery. None of the patients who received amifostine + 4-HC-purged marrow required a backup marrow fraction. Complete remissions were achieved in 83% of patients with measurable disease, with no difference between the two cohorts. Forty- three percent of patients remained alive and progression-free at a mean of 13 months posttransplant. There was no significant difference in the rate or pattern of relapse for patients whose marrow was purged with amifostine + 4-HC compared with those whose marrow was purged with 4-HC alone. Ex vivo treatment of marrow with amifostine significantly shortens the time to marrow recovery, thereby reducing the risk of myelosuppressive complications in breast cancer patients receiving high- dose chemotherapy and 4-HC-purged ABMS. Since supportive care requirements are also significantly decreased, amifostine may reduce the cost of such therapy.     

Fludarabine: a new agent with major activity against chronic lymphocytic leukemia

Fludarabine was used to treat 68 patients with previously treated chronic lymphocytic leukemia (CLL). Nine (13%) patients achieved a complete remission and 30 (44%) a partial remission. The response rates for Rai stages 0 to 2, 3, and 4 were 64%, 58%, and 50% respectively. Seventeen (43%) of the 40 Rai stage 1 to 3 patients and four (19%) of the Rai stage 4 patients returned to Rai stage 0. Survival was strongly correlated with the final Rai stage achieved. The survival of the 11 partial responders with residual disease consisting only of residual bone-marrow nodules was similar to the complete responders (36+ months) and superior to the other partial response patients (16 months). The response to fludarabine was rapid, with 36 (92%) of the 39 responders having achieved at least a partial response following the first three courses. Complete responses occurred in the blood, liver, spleen, and lymph nodes in 48% to 69% of the patients. Eradication of all disease in the bone marrow occurred in only 13% of the cases. Neutropenia and thrombocytopenia occurred in 56% and 25% of evaluable courses. Major infections occurred in 9% of evaluable courses and fevers of unknown origin or minor infections in 12% of courses respectively. Myelosuppression and infection were more common in patients with initial Rai stages 3 and 4 and in nonresponding patients. Other toxicity was mild. No CNS toxicity was noted.     

The effect of gastroenterology training on the efficiency and cost of care provided to patients with diverticulitis

BACKGROUND & AIMS: National trends emphasize the need for cost- efficient medical care with no diminution in quality. The most appropriate role for various physician groups has yet to be determined. The aim of this study was to investigate the efficiency of medical care provided by family practitioners (FPs), internists (IMs), and gastroenterologists (GIs) for acute diverticulitis. METHODS: All medicare hospitalizations from 1990 to 1993 in Illinois caused by acute diverticulitis, with FPs, IMs, or GIs as the primary attending physician, were included in the study. RESULTS: The primary attending physician was an FP in 1019 cases, an IM in 2535 cases, and a GI in 163 cases. The age and sex distributions were similar. The length of stay was significantly shorter (P < 0.0001) for GIs (7.4 +/- 6 days) than for FPs (7.9 +/- 14 days) or IMs (8.6 +/- 7 days). Readmission rate was significantly less (P < 0.03) for GIs (4.5%) than for FPs (7.7%) or IMs (10.0%). No significant differences were noted in complication rates or mortality. CONCLUSIONS: Patients with diverticulitis treated by GIs have a shorter hospital stay and a lower risk for readmission than patients treated by FPs or IMs. This improved quality of care should be considered by managed care organizations because they decide the role of various physician groups. (Gastroenterology 1997 Jun;112(6):1859-62)     

Demonstration of a blood-bone marrow barrier to macrophage colony- stimulating factor

Several previous studies suggested that murine macrophage colony- stimulating factor (CSF-1) might have impaired access to hematopoietic cells in the marrow. The apparent lack of hematopoietic responses to exogenous CSF and the finding of available or unoccupied CSF receptors despite saturating CSF levels in the serum led to studies of a potential blood-bone marrow barrier for this factor. Groups of mice were injected with pure unlabeled CSF-1 by either intravenous (IV) or intraperitoneal (IP) routes. Marrow and spleen cells were obtained at intervals after injection, held at 0 degree C, and assessed for changes in binding of 125I-CSF. Saturation of all available CSF receptors is achieved in vitro with 100 to 150 U CSF/mL. Despite achieving serum levels of 5,000 to 7,000 U/mL after IV injection of 25,000 units of CSF, less than 50% of the marrow receptors and less than 85% of the splenic receptors were saturated or downregulated. The decline in receptor availability was transient, with return of receptor sites in two to four hours. Increasing the IV dose to 125,000 units increased serum CSF values to approximately 20,000 U/mL and led to a virtual disappearance of available receptors for two to three hours. When administered IP, only approximately 40% of marrow and 80% of splenic receptors were affected for two hours. It was necessary to increase the dose of CSF to 250,000 units IP to saturate or downregulate receptors for three to four hours after injection. These observations indicate a marked blood-bone marrow barrier and lesser blood-spleen barrier for the transfer of serum CSF to responsive hematopoietic cells in vivo.     

Serum amyloid A serum concentrations and genotype do not explain low incidence of amyloidosis in Hyper-IgD syndrome

Background.?Hyper-IgD and periodic fever syndrome (HIDS) is an autosomal recessively inherited disorder characterized by recurrent episodes of fever and inflammation. Unlike other chronic inflammatory conditions, amyloidosis is very rare in HIDS. For deposition of amyloid of the AA type, high concentrations of SAA are a prerequisite, together with certain SAA1 gene polymorphisms. The SAA1.1 genotype predisposes for amyloidosis, while SAA1.5 genotype exerts a protective effect.

Aim of the study.?To determine if SAA concentrations and SAA1 gene polymorphisms could explain the virtual absence of amyloidosis in HIDS patients.

Methods.?We measured SAA and CRP concentrations in serum of 20 HIDS patients during an attack and during the asymptomatic phase. Genotype of SAA1 gene was determined in 60 HIDS patients.

Results.?SAA serum concentrations during attacks were very high (median 205?mg/l; range 75–520?mg/l, normal?<?3.1?mg/l). During attack-free periods 45% of patients still had elevated SAA concentrations. The distribution of the genotype of SAA1 gene in HIDS was similar to healthy controls (SAA1.1 0.41 vs. 0.50 p?=?0.32).

Conclusion.?Patients with HIDS have high SAA during attacks and show sub-clinical inflammation when asymptomatic. The low incidence of amyloidosis cannot be explained by a predominance of non amyloidogenic SAA related genotypes.