Evaluation of bone marrow megakaryocyte ploidy distributions in persons with normal and abnormal platelet counts

Using bone marrow smears of the type prepared routinely in clinical practice, we determined megakaryocyte ploidy distributions in five normal persons, eight patients with both normal platelet counts and normal bone marrow morphology, and 18 patients with quantitative platelet disorders. To include 2N and 4N megakaryocytes in the ploidy distribution histograms, all megakaryocytes were identified by serial immunologic labelling with rabbit antiserum to human platelet glycoproteins and rhodamine-conjugated goat anti-rabbit igG. Cell nuclei were concurrently Feulgen stained with bis-aminophenyl-oxdiazole, and the nuclear fluorescent signals were quantified photometrically. A modal megakaryocyte ploidy value of 32N was seen in 10 of the 13 persons with normal platelet counts, and geometric mean megakaryocyte ploidy values averaged 24.9N +/- 7.0N (arithmetic mean +/- SD). In these normal control individuals, 2N and 4N megakaryocytes accounted for 11.1% of all megakaryocytes, and 2.6% of the megakaryocytes were 128N. Shifts to a higher mean ploidy were observed in five of seven patients with idiopathic thrombocytopenic purpura, resulting from increased percentages of 64N and 128N megakaryocytes at the expense of 4N, 8N, and 16N cells. Shifts to lower ploidy were demonstrated in two patients with acute myelogenous leukemia and one patient each with thrombotic thrombocytopenic purpura and isoimmune thrombocytopenia. Four of five patients with essential thrombocythemia had strikingly abnormal megakaryocyte ploidy histograms characterized by the presence of unusually high ploidy 256N and 512N megakaryocytes. These 256N and 512N cells were virtually unique to the patients with essential thrombocythemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Examination of the correlation of serum metoclopramide levels with antiemetic efficacy in patients receiving cisplatin

The existence of a threshold serum metoclopramide level above which total protection from cisplatin-induced vomiting is more likely to occur has been proposed. We monitored serum metoclopramide levels prior to the third metoclopramide dose in the first cisplatin treatment cycle in patients receiving metoclopramide 2 mg/kg x 4 as part of a randomized double-blind cross-over study comparing single-agent metoclopramide with combination metoclopramide and dexamethasone. Serum samples from 35 patients (17 receiving single-agent metoclopramide and 18 receiving the combination) were analyzed using reverse-phase high-pressure liquid chromatography (HPLC). A wide variation in metoclopramide levels was observed (range 273-3380 ng/ml). Serum levels obtained from the same patient on multiple treatment cycles were well correlated, and the addition of dexamethasone did not alter serum metoclopramide levels. No threshold level could be identified for the two groups (single-agent or combination antiemetic therapy) considered individually or considered together. However, significantly more vomiting episodes and a lower incidence of total protection were noted in patients with metoclopramide levels above 1469 ng/ml receiving metoclopramide alone. This effect was nullified in the combination antiemetic group. Our data do not support a directly proportional relationship between serum metoclopramide level and antiemetic protection. However, a non-linear relationship with a possible agonist/antagonist effect is suggested.

Modest stimulatory effect of recombinant human GM-CSF on colony growth from peripheral blood human megakaryocyte progenitor cells

Recombinant human granulocyte-macrophage colony-stimulating factor (rGM-CSF) has been previously demonstrated to stimulate colony formation from human myeloid, erythroid, and multipotential stem cells. In this investigation, we evaluated the effects of rGM-CSF on colony growth by human megakaryocyte progenitors (CFU-Meg). rGM-CSF was tested at concentrations of 0.1-100 U/ml in plasma clot cultures of adherent-depleted normal peripheral blood mononuclear cells. Control cultures were concurrently prepared containing either no stimulator or megakaryocyte colony-stimulating factor (Meg-CSF) partially purified from aplastic canine serum. rGM-CSF increased megakaryocyte colony numbers from a baseline of 4.3 +/- 1.4 (+/- SEM) in the unstimulated cultures to a maximum of 21.0 +/- 5.3 colonies at an rGM-CSF concentration of 1.0 U/ml. Corresponding megakaryocytic colony size increased from 4.4 to 8.3 cells/colony. Further increasing the rGM-CSF concentration resulted in decreasing megakaryocyte colony growth, reaching 6.8 +/- 2.9 colonies at 100 U/ml. The maximum number of megakaryocyte colonies stimulated by rGM-CSF was only 23.3% of that achieved in the control cultures containing optimal concentrations of serum-derived Meg-CSF protein (2.0 mg/ml). Megakaryocyte colonies stimulated by rGM-CSF consisted of predominantly low ploidy cells approximately equally distributed in 2N, 4N, and 8N ploidy classes. There was no increase in ploidy with any rGM-CSF concentration. These data indicate that rGM-CSF has modest activity in stimulating human megakaryocyte colony growth that is substantially less than that present in serum-derived Meg-CSF. rGM-CSF appears to primarily affect the early mitotic phase of megakaryocyte colony development with little influence on megakaryocyte endoreduplication.

Echocardiographic mitral valve prolapse in ballet dancers: a function of leanness

To determine the prevalence of mitral valve prolapse in ballet dancers by echocardiography and to establish which anthropometric measurements best predict the presence of mitral valve prolapse, we compared 44 professional dancers (22 men and 22 women) with 52 controls (24 men and 28 women). Forty-eight percent (21 of 44) of dancers had echocardiographic mitral valve prolapse compared with 10% (5 of 52) of controls (p less than 0.01). The dancers weighed less than the controls and had significantly smaller bony diameters and body circumferences. However, only ponderal index was predictive of mitral valve prolapse in both dancers and controls. Thus, echocardiographic mitral valve prolapse is associated with low body weight relative to height and neither to ballet dancing nor to a distinct body habitus. Echocardiographic mitral valve prolapse may represent a normal variant in the majority of asymptomatic, thin subjects without auscultatory findings.

Interrelationship between mitosis and endomitosis in cultures of human megakaryocyte progenitor cells

Sera from dogs rendered aplastic by total-body irradiation stimulate human bone marrow megakaryocyte progenitors to form megakaryocyte colonies in plasma clot cultures. In this investigation, we evaluated the effects of varying concentrations of such sera on both the mitotic and endomitotic phases of human megakaryocyte development in vitro. When low concentrations of aplastic canine sera (2.5% to 5.0% [vol/vol]) were added to cultures of human peripheral blood mononuclear cells in place of normal AB serum, megakaryocyte colony formation was augmented fivefold, cell numbers per colony increased approximately 2.5-fold, and the geometric mean megakaryocyte ploidy almost doubled. Further increasing the aplastic canine serum concentration from 10% to 30% (vol/vol) stimulated no additional colony formation. However, there was a further augmentation of cell numbers per colony associated with a progressive decrease in the mean megakaryocyte ploidy. Megakaryocyte cultures were harvested after 7, 12, 15, and 19 days of incubation, and these demonstrated that the lower mean ploidy values found at the higher concentrations of aplastic canine serum did not result from delayed endoreduplication. At all aplastic serum concentrations evaluated, there existed a strong correlation between nuclear ploidy and cell diameter. We conclude that both the mitotic and endomitotic events in human megakaryocytopoiesis may be influenced by a factor or factors present in aplastic canine serum. At lower in vitro concentrations, such sera stimulate both mitosis and endomitosis, which promotes the development of megakaryocyte colonies composed of larger cells with a higher mean ploidy. With increasing aplastic serum concentrations, colony formation plateaus and mitosis is favored over endomitosis. This results in colonies composed of more numerous but smaller megakaryocytes with a lower mean ploidy. Our data suggest that the size and extent of polyploidization that can be achieved by a developing megakaryocyte may be influenced by the mitotic prior history of its immediate precursor cell.

Pharmacokinetic changes in aging

A multitude of factors influence the prescribing, dosing, and clinical monitoring of long-term drug therapy in elderly patients. These include life-style and environment, possible multiple disease states and concomitant medications, compliance, and continuous changes in physiology, all of which can--with advancing age--gradually alter the pharmacodynamics and pharmacokinetics of drugs. The physiologic changes associated with aging that can affect the absorption, distribution, excretion, and metabolism of drugs are reviewed and related to the clinical use of several drugs that are widely used in elderly patients. Important clinical factors may also magnify or counteract the physiologic changes that occur with respect to altered drug response. Finally, the pharmacokinetic properties of the available oral hypoglycemic agents are described as they relate to selection of an optimal drug in elderly diabetic patients.

Evaluation of arthritis self-management courses led by laypersons and by professionals

We compared the relative effectiveness of 2 arthritis patient education interventions. One intervention was modeled after that developed by Lorig, whereas the other had similar content but used health professionals rather than laypersons as instructors. Both interventions resulted in an increase in patients' knowledge of arthritis and in their use of exercise compared with a control group that received no intervention. However, neither intervention was any more effective than nonintervention in lessening patients' pain, improving their functioning, enhancing social support systems, lessening their depression, or improving their health behaviors beyond that of exercise. No differences in outcome measures were found between groups led by professional instructors and those led by lay instructors.

Left ventricular hypertrophy in athletes: an exercise-echocardiographic study

Left ventricular dimensions measured by M-mode echocardiography of 10 distance runners and 10 wrestlers were compared to 10 sedentary controls at rest and during 12 min of semisupine, graded bicycle ergometer exercise. At rest, runners and wrestlers demonstrated greater left ventricular mass compared to controls (mean values, 311.8 and 325.9 vs 215.9 g, respectively: P less than 0.05). In wrestlers, this was due to increased left ventricular septal (13.5 mm) and posterior wall thickness (12.9 mm) compared to controls (9.1 and 10.1 mm, respectively: P less than 0.05). In runners, this was due to increased left ventricular end-diastolic dimension (55.8 mm) compared to controls (49.7 mm) (P less than 0.05). During exercise, the different patterns noted at rest among the three groups in left ventricular dimensions and function persisted and were preserved: runners maintained a higher end-diastolic dimension compared to wrestlers and controls and greater shortening dimension compared to wrestlers. Absolute changes in left ventricular parameters from rest to exercise were not significantly different among the three groups.

CONCLUSIONS

1) different patterns of left ventricular hypertrophy exist among different types of athletes, with mainly increased wall thickness in primarily statically trained athletes and increased volume in dynamically trained athletes; and 2) these differences observed at rest persist during moderate-intensity, semisupine ergometer exercise and have direct functional significance, thereby emphasizing the differences found in cardiac dimensions among different types of athletes.

Clinical pharmacokinetics of high-dose metoclopramide in cancer patients receiving cisplatin therapy

Using a sensitive and specific high-pressure liquid chromatographic (HPLC) assay, we measured serum levels of metoclopramide in 18 cancer patients receiving high-dose intravenous (IV) therapy to prevent cisplatin-induced emesis. Ten patients were treated with one or more courses with metoclopramide alone (1.0 to 3.0 mg/kg) in an open-label study, and eight patients were treated with a fixed 2.0 mg/kg dose of metoclopramide with or without adjunct dexamethasone (20 mg) using a randomized, crossover design. The pharmacokinetics of metoclopramide were determined, and the relationship between serum levels and clinical response was evaluated. The pharmacokinetic parameters of high-dose metoclopramide were found to be similar to those reported for standard promotility doses, and no dose dependency was demonstrated over the range of doses studied. No clear correlation between serum metoclopramide levels and prevention of cisplatin-induced emesis was observed. The addition of dexamethasone resulted in clinical improvement in two of eight patients, but had no effect on serum metoclopramide levels or kinetic parameters. Results in this study population do not show metoclopramide levels to be related to antiemetic effect following IV cisplatin therapy.

Lethal atherosclerosis associated with abnormal plasma and tissue sterol composition in sitosterolemia with xanthomatosis

Tissue sterol composition was determined in an 18-year-old male with sitosterolemia with xanthomatosis who died suddenly and whose coronary and aortic vessels showed extensive atherosclerosis and, for comparison, in an 18-year-old male with minimal atherosclerosis who died accidently. Sterols in the control tissues (plasma, erythrocytes, cardiac muscle, lung, liver, aorta, and brain) contained cholesterol with only trace amounts of cholestanol. In contrast, sterols in corresponding tissues of the sitosterolemic subject (except brain) were composed of cholesterol, increased amounts of plant sterols, campesterol and sitosterol, and 5 alpha-saturated stanols, cholestanol, 5 alpha-campestanol, and 5 alpha-sitostanol, that were deposited in approximately the same ratio as present in plasma. However, sitosterolemic brain sterol composition resembled that of the control brain with cholesterol and only trace amounts (less than 1%) of cholestanol and phytosterols. The sitosterolemic aorta was extensively atherosclerotic and contained more than twice the quantity of sterols as the control aorta (5.6 mg/g versus 2.6 mg/g) with increased amounts of cholesterol, plant sterols, and 5 alpha-saturated stanols. These results indicate that cholesterol, plant sterols, and 5 alpha-stanols are deposited prematurely and are associated with accelerated atherosclerosis in subjects with sitosterolemia with xanthomatosis.

Biochemical and immunocytological localization of molluscan small cardioactive peptides in the nervous system of Aplysia californica

High pressure liquid chromatography (HPLC) followed by bioassay on isolated snail hearts were used to locate two related peptides, termed small cardioactive peptides A and B (SCPA and SCPB) in each of the central ganglia of Aplysia. The peptides are most concentrated in the buccal ganglia, the ganglia involved in the control of feeding movements. Immunocytology with antisera raised to conjugated SCPB stained three groups of neurons in the buccal ganglia. One group consisted of relatively small neurons that were tightly clustered. The second group was comprised of larger neurons that were more scattered. The third group was made up of several neurons including the two largest in the ganglia, identified cells B1 and B2. B1 and B2 and other neurons in this group innervate the gut by way of the esophageal nerve. HPLC-bioassay of single, individually dissected B1 or B2 neurons demonstrated that the two peptides are present in a single cell. For B2, but not B1, choline injected into the cell body was converted to the conventional transmitter, acetylcholine. This indicates that, in addition to the two peptides, B2 also contains choline acetyltransferase, and raises the possibility that acetylcholine and the SCPs may act as co-transmitters in B2. Strong immunocytological staining of fibers and varicosities was observed in the neuropilar region of the cerebral, pleural, pedal, and abdominal ganglia. In addition to the buccal ganglia, immunoreactive neurons were observed in all of the other central ganglia. The high concentration of the SCPs and the relatively large number of immunoreactive neurons in the buccal ganglion suggest a particularly important role of these peptides specifically in feeding behavior. However, the widespread occurrence of the SCPs in fibers and neuronal cell bodies throughout the nervous system suggests that these peptides also may have additional behavioral functions in Aplysia.

A Nutritional and Hematologic Assessment of Elite Ballet Dancers

In brief: We studied the nutritional and hematologic status of 22 professional ballet dancers (10 men, 12 women, mean age 25), from American Ballet Theatre by analyzing daily dietary intake and laboratory data including blood vitamin assays. The dancers had law percent body fat. Daily calorie intake was 2,967 ± 667 kcal for men and 1,673 ± 450 kcal for women. Carbohydrate consumption (38% of the total daily calorie intake for men and 50% for women) was too law for efficient energy use. Hemoglobin and red cell indexes were normal, but serum ferritin was below normal in eight women and three men. Serum chemistry values were normal. Blood vitamin assays were normal in all dancers, reflecting widespread use of vitamin supplements. By sports medicine standards, the dancers' law calorie diets were suboptimal for strenuous physical exercise.

Effect of diltiazem on renal clearance and serum concentration of digoxin in patients with cardiac disease

The effect of diltiazem on digoxin serum concentration was evaluated in 9 patients who had been treated chronically for heart disease with digoxin, 0.25 mg/day. The indications for digoxin therapy were arrhythmias in 5 patients and mild heart failure in the other 4. Renal digoxin clearance was also evaluated in 8 of these patients. Serum digoxin concentration was measured at control, 7 +/- 2 days after initiation of 120 mg/day of diltiazem and 11 +/- 5 days after increasing the dose of diltiazem to 240 mg/day. Serum digoxin concentration was 0.9 +/- 0.4 ng/ml at control, 0.8 +/- 0.4 ng/ml with 120 mg/day of diltiazem, and 0.8 +/- 0.3 ng/ml during therapy with 240 mg/day. The differences between these values were not significant. Renal digoxin clearance also did not show a significant change after diltiazem therapy (44 +/- 15 ml/min before diltiazem and 46 +/- 13 ml/min with 240 mg/day of diltiazem). This study shows no effect of diltiazem in doses of 120 to 240 mg/day on serum digoxin concentration or renal digoxin clearance in patients who are treated chronically for heart disease with digoxin. In this dose range, diltiazem has advantages over verapamil, which markedly elevates digoxin levels.

Effects of glycine and GABA on the ganglion cels of the retina of the skate Raja erinacea

Application of glycine and GABA caused inhibition of light-evoked activity from different populations of 'ON' center ganglion cells in the retina of the skate (Raja erinacea). Cells affected by glycine were not affected by GABA and vice-versa. Addition of 100 microM strychnine to the glycine-containing perfusate caused a resumption in light-evoked responses of the cells. The action of GABA was antagonized by 100 microM bicuculline methochloride, but not by picrotoxin. Autoradiography revealed the presence of [3H]glycine accumulating amacrine cells.

Hyperuricemia in glycogen storage disease type I. Contributions by hypoglycemia and hyperglucagonemia to increased urate production

Studies were performed to determine whether hypoglycemia or the glucagon response to hypoglycemia increases uric acid production in glycogen storage disease type I (glucose-6-phosphatase deficiency). Three adults with this disease had hyperuricemia (serum urate, 11.3-12.4 mg/dl) and reduced renal clearance of urate (renal urate clearance, 1.1-3.1 ml/min). These abnormalities were improved in one patient by intravenous glucose infusion for 1 mo, suggesting a role for hypoglycemia and its attendant effects on urate metabolism and excretion. A pharmacologic dose of glucagon caused a rise in serum urate from 11.4 to 13.0 mg/dl, a ninefold increase in urinary excretion of oxypurines, a 65% increase in urinary radioactivity derived from radioactively labeled adenine nucleotides, and a 90% increase in urinary uric acid excretion. These changes indicate that intravenous glucagon increases ATP breakdown to its degradation products and thereby stimulates uric acid production. To observe whether physiologic changes in serum glucagon modulate ATP degradation, uric acid production was compared during saline and somatostatin infusions. Serum urate, urinary oxypurine, radioactivity, and uric acid excretion increased during saline infusion as patients became hypoglycemic. Infusion of somatostatin suppressed these increases despite hypoglycemia and decreased the elevated plasma glucagon levels from a mean of 81.3 to 52.2 pg/ml. These data suggest that hypoglycemia can stimulate uric acid synthesis in glucose-6-phosphatase deficiency. Glucagon contributes to this response by activating ATP degradation to uric acid.

Comparative radiopharmacokinetics of 18F-5-fluorouracil administered i.v. to rats bearing a mammary tumor

In an attempt to compare the efficacy of various 5-fluorouracil (5-FU) regimens, we studied the kinetics of 18F-labeled and unlabeled 5-FU in rats. 18F-5-FU was synthesized in our laboratory and was administered in tracer doses to Fischer rats bearing either the 13762 or the R3230 mammary adenocarcinoma, and to Sprague-Dawley rats bearing the Walker-256 carcinosarcoma, with or without pre-treatment with a therapeutic dose of unlabeled 5-FU. In addition, the non-radioactive 5-FU was administered to control rats of both strains. All animals were followed for 70 min either by measuring their 18F blood levels continuously using an extracorporeal blood-loop, or by determining their 5-FU blood levels at discrete time intervals. The biphasic kinetic profile was characterized by determining alpha and beta rate constants and their corresponding half-lives. Differences in 18F elimination, as measured by the area under the curve during the elimination phase, were observed between the pre-treated 13762-bearing rats and the untreated group bearing the same tumor, as well as the pre-treated non-tumored controls and both W-256-bearing groups. Such differences could reveal changes in the ability of those rats to metabolize 5-FU, and hence correlate to the level of active metabolite(s) available to their tumor sites.

Effect of actinomycin D on iodide transport in FRTL-5 thyroid cells

TSH-induced I- uptake in FRTL-5 thyroid cells requires new protein synthesis. During the induction of I- uptake, which takes nearly 60 h to reach its maximum, two waves of protein synthesis can be identified: one during the first 8 h and another after 24-30 h, each involving different proteins. Cycloheximide (CH) added during the first 10 h of a 48-h incubation with TSH completely inhibits the induction of I- uptake; 58% inhibition is observed with CH added at 24 h; no inhibition is observed when CH is added 36 h after TSH. Like CH, actinomycin D (ActD), added at the beginning of the 48-h period, inhibits TSH induction of I- uptake; partial inhibition (83%, 72%, and 28%) is observed when ActD is added at 1, 5, and 10 h, respectively. Treatment with ActD at 24 h (ActD-treated cells), however, paradoxically increases I- uptake (1.8- to 3.5-fold over the control value). The characteristics of I- uptake in ActD-treated cells are the same as those in untreated cells; both are Na+ dependent and can be inhibited in a comparable manner by anions. Kinetic measurements of I- transport indicate that ActD increases the rate of I- influx (2-fold or greater increase in maximum velocity without a significant change in Km), with only minor changes in I- release. Enhanced I- uptake in ActD-treated cells is inhibited by the simultaneous (24-h) administration of CH, indicating that protein synthesis is required for the late ActD effect. Despite an overall 2-fold decrease in protein synthesis in cells treated with ActD at 24 h, the synthesis of individual proteins maximally induced by TSH during the first 8 h is increased, whereas that of some proteins maximally synthesized after 24-30 h is markedly reduced. The present data indicate that TSH-induced I- uptake in FRTL-5 cells involves a regulatory action of TSH that operates at the mRNA level.