Effects of parathyroid hormone depletion in dogs with induced renal failure

Six parathyroidectomized (PTX) and 6 control dogs had renal mass reduced by 15/16, and were studied for effects of parathyroid hormone depletion on progression of renal failure. All PTX dogs and 4 of 6 control dogs survived until necropsy after 32 weeks. Plasma parathyroid hormone concentration was undetectable in PTX dogs throughout the study, but was greater than normal in control dogs. Serum inorganic phosphate (P) concentration was increased in PTX dogs (6.8 +/- 0.1 mg/dl) and in control dogs (7.5 +/- 0.2), but did not differ significantly (P = 0.254) between groups. Ionized blood calcium values (Ca2+) were significantly (P = 0.014) lower in PTX dogs (1.31 +/- 0.01 mmol/L) than in control dogs (1.36 +/- 0.00 mmol/L), but were more variable in PTX dogs. Values in PTX dogs were not significantly different from those in control dogs for glomerular filtration rate (P = 0.914), plasma creatinine concentration (P = 0.903), and urine protein to creatinine ratio (P = 0.756) determined at intervals during the study. Terminal glucose tolerance and plasma insulin concentrations, P tolerance, and renal P excretion did not differ between groups. Histologic comparison of kidneys removed during reduction of renal mass with kidneys removed at necropsy revealed development of lesions in both groups of dogs, and no protective effect from parathyroidectomy. Mineral analysis of aorta, brain, heart, lungs, and skeletal muscle obtained at necropsy revealed no significant difference between PTX and control groups. Renal cortical calcium concentration was significantly (P < 0.05) greater in kidneys obtained at necropsy then in kidneys obtained during nephrectomy, but PTX did not protect renal cortex from calcium deposition.

Effect of total body irradiation, busulfan-cyclophosphamide, or cyclophosphamide conditioning on inflammatory cytokine release and development of acute and chronic graft-versus-host disease in H-2-incompatible transplanted SCID mice

In a previous study, we found that total body irradiation (TBI) was essential to induce acute graft-versus-host disease (GVHD) after allogeneic H-2-incompatible splenocyte (SP) transplantation in SCID mice. SCID mice (H-2d) conditioned with cyclophosphamide and transplanted intravenously (IV) with 5 x 10(7) C57BL/6 (H-2b) SP developed chronic GVHD within 3 months posttransplant without any evidence of preceding acute GVHD. In this study, SCID mice were conditioned with 4 Gy TBI or non-TBI regimens, either BuCy2 (busulfan 4 mg/kg/d + cyclophosphamide 100 mg/kg/d for 2 days) or Cy5 (cyclophosphamide 100 mg/kg/d for 5 days), and then transplanted IV with 5 x 10(7) SP. The TBI-conditioned mice were further divided into tree transplant groups: (1) TBI and SP administered the same day (TBI + D0 SP), (2) SP administered 4 days post-TBI (TBI + D4 SP), and (3) SP administered 7 days post-TBI (TBI + D7 SP). The severity of GVHD was compared among these groups by clinical and histologic grading. Twenty-eight of 28 mice treated with TBI + D0 SP died of acute GVHD, with overwhelming diarrhea by day 15 posttransplantation. Sixteen mice treated with either TBI + D4 SP or TBI + D7 SP developed acute GVHD, but none of them died of this disorder during 30 days posttransplantation. The mice conditioned with non-TBI regimens developed chronic GVHD within 3 months without showing any detectable signs of acute GVHD. Serum and in situ colonic cytokines were determined by enzyme-linked immunosorbent assay and immunohistology respectively. TBI itself significantly increased both serum and colonic tumor necrosis factor-alpha (TNF-alpha), interleukin-1 alpha (IL-1 alpha), and IL-6 when compared with non-TBI regimens and normal controls. TNF-alpha appeared in the serum and colon 4 hours post-TBI and peaked in 24 hours, followed by increasing IL-1 alpha and then IL-6 levels. TNF-alpha and IL-1 alpha decreased rapidly within 3 to 5 days post-TBI if no allogeneic cells were transplanted. Histoincompatible transplantation augmented cytokine release, which remained elevated on day 10 in these animals. Mice treated with TBI + D0 SP developed the most severe acute GVHD and had the highest levels of TNF-alpha, IL-1 alpha, and IL-6. The BuCy2-conditioned mice had the lowest cytokine levels and developed no acute GVHD. When the mice transplanted with TBI + D0 SP were treated immediately with recombinant soluble human TNF receptor (rhuTNFR:Fc) 100 micrograms/d intraperitoneally and for the subsequent 15 days acute GVHD mortality was significantly reduced from 100% to 50% (P < .001).(ABSTRACT TRUNCATED AT 400 WORDS)

Smoking and health in substance-abusing adolescents: a two-year follow-up

OBJECTIVE

To examine the prevalence and persistence of cigarette smoking along with health outcomes in a clinical sample of substance-abusing adolescents.

DESIGN

This is a 2-year prospective case series study.

SETTING

Subjects were recruited from two private, hospital-based inpatient adolescent substance abuse treatment facilities.

PARTICIPANTS

A consecutive sample of 166 adolescents, ages 12 to 18, meeting Diagnostic and Statistical Manual of Mental Disorders (3rd ed, revised) criteria for substance abuse participated in the present investigation. Of the original sample, 154 and 144 were interviewed 12 and 24 months after discharge, respectively.

MEASUREMENT AND RESULTS

Information regarding cigarette smoking, drug and alcohol use, and respiratory problems was based on self-report by the adolescents and was corroborated by parent interview. The prevalence of smoking in this sample of teens immediately before treatment was 85%. Sixty-one percent of the sample smoked 1/2 pack or more/day and 75% were daily smokers. Although prevalence (74 and 77%) and average daily cigarette consumption (11.1 and 10.7 cigarettes daily) decreased at 12 and 24 months after treatment, rates remained very high. Teens reporting posttreatment respiratory problems smoked more, and heavier smokers at the time of treatment were more likely to report respiratory problems at follow-up than lighter smokers.

CONCLUSIONS

Substance-abusing teens smoke at rates far and above those of the general adolescent population. Further, these teens appear at increased risk for negative health consequences regardless of posttreatment drug and alcohol use. These findings highlight the importance of preventing adolescent cigarette smoking by substance abuse treatment programs.

Alteration of hydroxylapatite coatings exposed to chemicals used in histological fixation

Histological evaluation of retrieved devices allows for assessment of the biological response to the implants. Interaction between the biomaterial and the fluids used in the processing may alter the appearance or composition of the device. This may result in artifacts due to processing which are misinterpreted as being caused by the biological response. Alteration by the fluids used in fixation may be particularly important with materials that have a propensity to interact with aqueous environments, as in the case of calcium phosphate ceramics. Therefore, we examined the effects of various standard histological fixation techniques on hydroxylapatite coated metal implants. Of the techniques examined, fixation with ethanol appeared to affect the surface morphology the least, whereas fixation in unbuffered formalin appeared to affect the bulk composition of these samples the least. Fixation in buffered formalin resulted in marked changes in both surface morphology and bulk composition.

Antipyrine and caffeine dispositions in clinically normal dogs and dogs with progressive liver disease

Dispositions of caffeine and antipyrine were compared as indicators of decreasing hepatic function in dogs with experimentally induced progressive liver disease. Dimethylnitrosamine, a hepatospecific toxin, was administered orally to 16 dogs; 6 dogs served as controls (group 1). Three classes of liver disease were defined by histologic features: mild (group 2; n = 5), moderate (group 3; n = 6), and severe (group 4; n = 5). Disposition of antipyrine, and 24 hours later, caffeine was studied 3 weeks after the last dose of toxin in each dog. For both drugs, rapid IV administration of 20 mg/kg of body weight was administered and serum samples were obtained at intervals for determination of at least 5 terminal-phase drug half-lives. For both drugs, clearance and mean residence time differed among groups (P < or = 0.01). Clearance of antipyrine and caffeine was decreased in groups 3 and 4, compared with groups 1 and 2. Antipyrine and caffeine mean residence times were longer in group-3 dogs, compared with dogs of groups 1 and 2. Correction of caffeine and antipyrine clearances for hepatic weight increased discrimination between groups 3 and 4. The clearance and mean residence time ratios of antipyrine to caffeine were calculated for each group and, when compared with values for group-1 dogs, were used to test for differences between the 2 drugs in response to disease. Ratios did not differ among groups. These results indicate that the disposition of antipyrine and caffeine may change similarly with progression of dimethylnitrosamine-induced liver disease.

Cellular uptake of titanium and vanadium from addition of salts or fretting corrosion in vitro

The use of titanium and titanium-6% aluminum-4% vanadium alloy for dental and orthopedic implants has increased in the last decade. The implants are presumed to be compatible because osseointegration, bony apposition, and cell attachment are known. However, the cellular association of titanium and vanadium have remained unknown. This study examined the uptake of salts or fretting corrosion products. Titanium was not observed to be toxic to the cells. Vanadium was toxic at levels greater than 10 micrograms/mL. The percentage of cellular association of titanium was shown to be about 10 times that of vanadium. The percentage of cellular association of either element was greater from fretting corrosion than from the addition of salts. The presence of vanadium did not affect the cellular uptake of titanium. The presence of titanium decreased the cell association of vanadium.

Characterization of calcium phosphate powders by ESCA and EDXA

Calcium phosphate (CaP) materials can be well characterized by traditional methods such as wet chemistry and X-ray diffraction (XRD). These methods, however, offer limitations when non-destructive evaluation of CaP coatings on curved surfaces is required. Since the source powders for these coatings are generally commercially available CaP powders, careful characterization of the source powders may allow inferences to be made regarding the effects of plasma spraying on coating composition. Nine commercially available CaP powders were characterized by scanning electron microscopy, wet chemistry and XRD. These techniques showed that major differences exist between individual powders claiming to be hydroxyapatite. Analysis of these nine powders by electron spectroscopy for chemical analysis (ESCA) and energy dispersive X-ray analysis (EDXA) suggest that these techniques can provide the chemical composition of CaP in a non-destructive manner and thus may be of use in determining the composition of CaP in configurations (such as coatings on metal surfaces) not readily amenable to traditional methods. A calibration curve is required, however, to relate this surface chemical composition result to the material's bulk composition as determined by wet chemistry analysis. Errors of less than 10% can be obtained using ESCA and EDXA. These studies suggest that non-destructive chemical composition evaluation by EDXA and ESCA may also be applicable to CaP coatings.

Concentration of ceftiofur metabolites in the plasma and lungs of horses following intramuscular treatment

Ceftiofur sodium, a broad spectrum cephalosporin antibiotic approved for veterinary use, is metabolized to desfuroylceftiofur which is conjugated to micro as well as macromolecules. Twelve horses, weighting 442-618 kg, were injected intramuscularly with a single dose of 2.2 mg ceftiofur/kg (1.0 mg/lb) body weight. Blood was collected at various intervals over 24 h after treatment. Three groups of four horses each were euthanized and lungs were collected at 1, 12, and 24 h after treatment. The concentration of desfuroylceftiofur and desfuroylceftiofur conjugates in the plasma and lungs was determined by converting them to desfuroylceftiofur acetamide (DCA) and measured DCA by high performance liquid chromatography with UV detection. The average maximum concentration (Cmax) of desfuroylceftiofur and related metabolites in plasma expressed as ceftiofur equivalents was 4.46 +/- 0.93 micrograms/ml occurred at 1.25 +/- 0.46 h after treatment. These concentrations declined to 0.99 +/- 0.16, 0.47 +/- 0.15 and 0.17 +/- 0.02 microgram/ml at 8, 12, and 24 h, respectively. The mean residence time of ceftiofur metabolites was 6.10 +/- 1.27 h. Concentrations of desfuroylceftiofur and desfuroylceftiofur conjugates in the lungs of horses expressed as ceftiofur equivalents were 1.40 +/- 0.36, 0.27 +/- 0.07, and 0.15 +/- 0.08 micrograms/ml at 1, 12, and 24 h, respectively. These concentrations of the drug at 12 and 24 h in lung homogenate were similar but slightly lower than plasma concentrations in the same horses, and the plasma pharmacokinetic values including half-life were similar to those observed at the approved dose of 1.1-2.2 mg ceftiofur/kg body weight administered intramuscularly once daily for 3-5 days in cattle.

Effect of endotoxin on tirilazad mesylate (U74006F) pharmacokinetic parameters in neonatal calves

The pharmacokinetics of the 21-aminosteroid tirilazad mesylate (U74006F) were studied in both healthy and endotoxin-challenged neonatal calves. Group I calves received a 3-h intravenous (i.v.) infusion of sterile saline (250 ml) and tirilazad mesylate (1.5 mg/kg i.v.) 1 h after the start of the saline infusion. Group II calves received tirilazad mesylate 1 h after the start of a 3-h endotoxin (3.25 micrograms/kg) infusion. The data obtained indicate that tirilazad mesylate follows a biexponential equation in neonatal calves. The area-derived volume of distribution (Vdarea) was 9.68 +/- 0.759 l/kg in healthy calves and 6.53 +/- 1.20 l/kg in endotoxin-challenged calves (P < 0.05). Similarly, significant (P < 0.05) decreases in steady-state volume of distribution (Vdss) and central volume (Vc) were observed in endotoxin-challenged calves (5.32 +/- 0.979 l/kg and 1.68 +/- 0.189 l/kg, respectively) compared to healthy calves (7.58 +/- 0.834 l/kg and 2.43 +/- 0.452 l/kg, respectively). A and B were significantly larger in endotoxin-challenged calves than in healthy calves (P < 0.05). Rate constants and their associated half-lives, area under the curve and clearance were not significantly altered by endotoxin challenge. Serum thromboxane generation (ex vivo) was evaluated as a marker of the drug's physiologic activity. There was no significant difference in thromboxane generation during clotting of blood from healthy and endotoxemic calves treated with tirilazad mesylate.

Effects of the 21-aminosteroid U-74389G on ischemia and reperfusion injury of the ascending colon in horses

Sixteen horses were allotted at random to 3 groups: vehicle only; low dosage (vehicle and 3 mg of U-74389G/kg of body weight); high dosage (vehicle and 10 mg of U-74389G/kg). These solutions were given prior to reperfusion. The ascending colon was subjected to 2 hours of ischemia followed by 2 hours of reperfusion. Before, during, and after ischemia, full-thickness colonic tissue biopsy specimens were obtained for measurement of malondealdehyde (MDA) concentration and myeloperoxidase activity and for morphologic evaluation. Although increases were not significant, MDA concentration and myeloperoxidase activity increased during ischemia and reperfusion. Administration of U-74389G did not have significant effects on MDA concentration and myeloperoxidase activity. However, the lower dosage tended (P = 0.08) to reduce myeloperoxidase activity at 30 and 60 minutes of reperfusion. In horses of the vehicle-only group, ischemia induced a decrease in mucosal surface area that was continued into the reperfusion period (P < or = 0.05). Administration of U-74389G at both dosages (3 and 10 mg/kg) prevented the reperfusion-induced reduction in mucosal surface area, which was significant at 60 minutes (high dosage; P = 0.05) and 90 minutes (low and high dosages; P = 0.02). After initial reduction in horses of all groups, mucosal volume increased for the initial 60 minutes of reperfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetics of midazolam administered concurrently with ketamine after intravenous bolus or infusion in dogs

Midazolam, a water-soluble benzodiazepine tranquilizer, has been considered by some veterinary anaesthesiologists to be suitable as a combination anaesthetic agent when administered concurrently with ketamine because of its water solubility and miscibility with ketamine. However, the pharmacokinetics of midazolam have not been extensively described in the dog. Twelve clinically healthy mixed breed dogs (22.2-33.4 kg) were divided into two groups at random and were administered ketamine (10 mg/kg) and midazolam (0.5 mg/kg) either as an intravenous bolus over 30 s (group 1) or as an i.v. infusion in 0.9% NaCl (2 ml/kg) over 15 min. Blood samples were obtained immediately before the drugs were injected and periodically for 6 h afterwards. Serum concentrations were determined using gas chromatography with electron-capture detection. Serum concentrations were best described using a two-compartment open model and indicated a t1/2-alpha of 1.8 min and t1/2-beta of 27.8 min after i.v. bolus, and t1/2-alpha of 1.35 min and t1/2-beta of 31.6 min after i.v. infusion. The calculated pharmacokinetic coefficient B was significantly smaller after i.v. infusion (429 +/- 244 ng/ml) than after i.v. bolus (888 +/- 130 ng/ml, P = 0.004). Furthermore, AUC was significantly smaller after i.v. infusion (29,800 +/- 6120 ng/h/ml) than after i.v. bolus (42,500 +/- 8460 ng/h/ml, P < 0.05), resulting in a larger ClB after i.v. infusion (17.4 +/- 4.00 ml/min/kg than after i.v. bolus (12.1 +/- 2.24 ml/min/kg, P < 0.05). No other pharmacokinetic value was significantly affected by rate of intravenous administration.

Reduction of fretting corrosion of Ti-6Al-4V by various surface treatments

Titanium and titanium-6% aluminum-4% vanadium (Ti-6Al-4V) are known to be biocompatible and corrosion resistant. However, there have been numerous reports of elevated tissue levels of titanium due to passive dissolution, wear, or fretting corrosion of implants. Studies were undertaken to determine whether the fretting corrosion of Ti-6Al-4V could be reduced by surface treatment of one or both surfaces in a fretting situation. Three different surface treatments were studied: ion implantation, physical vapor deposition nitriding, and plasma ion nitriding. The specimens used were screws fretting against the countersinks of a two-hole plate. Fretting corrosion was assessed by weight loss, by chemical analysis of test solutions, and by scanning electron microscopy. Surface treatment of one component, the screws, resulted in reduction in the release of titanium to only 18-32% of that seen with the untreated controls. Weight loss of the untreated plates fretted against physical vapor deposition nitrided screws and plasma ion nitrided screws was reduced to 31 and 38% of the control, respectively. The weight loss of plasma nitrided screws was only 30% that of the control. Nitriding of both plates and screws resulted in a further decrease in plate weight loss and metal release. Plasma ion nitriding of both components had the most significant effect, with the weight loss and titanium release being only 11 and 2% of the control values, respectively.

Effects of inhibition of nitric oxide synthase on systemic arterial pressure and renal vascular resistance in cats

These studies were undertaken to examine the systemic and renal effects of the pharmacological inhibition of endothelium-derived nitric oxide (EDNO) in cats. In six healthy cats, the intravenous infusion of nitro-L-arginine at a dose of 100 micrograms kg-1 bodyweight min-1 resulted in a marked increase (P < 0.001) in mean arterial pressure from the control value of 116.7 +/- 4.6 mmHg to 154.2 +/- 6.8 mmHg and an increase (P < 0.05) in renal vascular resistance from the control value of 3.69 +/- 0.33 mmHg min ml-1 to 6.83 +/- 1.15 mmHg min ml-1. The increase in renal vascular resistance was generalised, with comparable increments in preglomerular and postglomerular vascular resistance. Mean values for glomerular capillary pressure (61.1 +/- 1.9 vs 61.9 +/- 1.6 mmHg), calculated from the sum of arterial colloid osmotic pressure plus proximal tubule stop-flow pressure, did not change in response to the infusion of nitro-L-arginine. However, there was a marked reduction in renal blood flow (29.4 +/- 3.1 to 16.9 +/- 2.3 ml min-1, P < 0.01) and glomerular filtration rate (5.22 +/- 0.57 to 3.52 +/- 0.45 ml min-1, P < 0.01). These results provide evidence that EDNO plays an important role in the basal regulation of systemic arterial blood pressure and renal haemodynamics in cats.

The relation of lipoprotein[a] concentrations and apolipoprotein[a] phenotypes with asymptomatic atherosclerosis in subjects of the Atherosclerosis Risk in Communities (ARIC) Study

Plasma levels of lipoprotein[a] (Lp[a]) are associated with increased risk of coronary artery disease and show an inverse correlation with apolipoprotein[a] (apo[a]) molecular weight. We determined Lp[a] levels and apo[a] phenotypes in 171 cases with preclinical extracranial carotid atherosclerosis as ascertained by B-mode ultrasound and in 274 control subjects free of carotid atherosclerosis. Lp[a] protein levels measured by enzyme-linked immunosorbent assay ranged from 4 to 361 micrograms/mL in cases and from 2 to 392 micrograms/mL in controls, but median levels of Lp[a] were higher in cases than in controls (51 micrograms/mL versus 33 micrograms/mL, P < .003). In both groups, all 11 apo[a] polymorphs that are resolved by the procedure used were present, resulting in 43 and 39 different apo[a] phenotypes in cases and controls, respectively. An inverse relation between apo[a] polymorph size and Lp[a] level was observed in both cases (r = -0.49, P < .001) and controls (r = -0.34, P < .001). Apo[a] phenotype distributions were similar in cases and controls. However, in 17 phenotypes with three or more subjects per group, the difference of mean Lp[a] concentrations between cases and controls was 32 +/- 36 micrograms/mL (mean +/- SD). Thus, the higher Lp[a] levels in cases were not associated with a greater prevalence of small apo[a] polymorphs. Stepwise logistic regression analyses of known risk factors for coronary heart disease showed that plasma Lp[a] concentration was an independent predictor of case-control status, while Lp[a] phenotype was not, irrespective of the presence or absence of Lp[a] concentration in the model.(ABSTRACT TRUNCATED AT 250 WORDS)

Endogenous creatinine clearance measurement of glomerular filtration rate in dogs

Renal clearance procedures were performed on adult mixed-breed dogs with a wide range of renal function. Endogenous creatinine clearance was computed after analyzing plasma and urine for creatinine by use of 2 methods, PAP and kinetic Jaffe. For 20-minute clearance procedures, [14C]inulin clearance was measured simultaneously with endogenous creatinine clearance. For 111 twenty-minute clearance procedures performed on 24 dogs, [14C]inulin clearance was highly correlated with creatinine clearance for both methods of creatinine analysis (R2 = 0.979 for [14C]inulin-PAP; R2 = 0.943 for [14C]inulin-Jaffe). The absolute values for PAP and [14C]inulin clearance were nearly the same (PAP-to-[14C]inulin clearance ratio = 1.03 +/- 0.08), but those for Jaffe clearance were substantially less than those for [14C]inulin clearance (Jaffe-to-[14C]inulin clearance ratio = 0.88 +/- 0.10). The Jaffe-to-[14C]inulin clearance ratio was inversely correlated with degree of renal function (R2 = 0.464), whereas the PAP-to-[14C]inulin clearance ratio was not correlated with degree of renal function (R2 = 0.060). Thus, Jaffe-determined creatinine clearance varied, in relation to [14C]inulin clearance, depending on degree of renal function. In 4 clinically normal dogs, 20-minute and 24-hour sample collections analyzed by use of the PAP method gave clearance values significantly greater, for both periods, than did Jaffe analyses. The PAP-determined creatinine clearance values were less than, but not significantly different from 20-minute exogenous creatinine clearance values determined 10 days after 24-hour collections.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of hydration state on renal functions of dogs

Clinically normal dogs were evaluated in states of dehydration, euhydration, and after fluid administration to determine effects of hydration state on renal clearance values. Endogenous creatinine, exogenous creatinine, and [14C]inulin clearances, were determined to measure glomerular filtration rate (GFR); in some experiments p-aminohippurate clearance was determined to measure renal plasma flow. Dehydration caused significant (P < 0.05) decrease in clearance values, compared with euhydration, and clearance values during euhydration were significantly (P < 0.05) less than values obtained after a single gavage with water (30 ml/kg of body weight). Sustained administration of 3 fluid regimens was evaluated for effects on clearance values (treatment A = 30 ml of lactated Ringer's solution/kg/h; treatment B = 30 ml of water/kg by gavage hourly; treatment C = 10 ml of glucose:lactated Ringer's solution/kg/h). All regimens of fluid therapy caused significant P < 0.05), progressive increases in GFR, but treatment C resulted in the most stable GFR values. Increases in clearance values were associated with positive fluid balance; the rate of fluid administration was greater than the rate of urine formation. Data from 285 GFR determinations on 85 dogs were evaluated retrospectively. For each determination, three 20-minute urine collections were made beginning 40 minutes after 30 ml of water/kg was given by gavage. Values between collections were significantly (P < 0.05) different, but varied by < 3%. Comparison of methods for measurement of GFR indicated that endogenous creatinine clearance and [14C]inulin clearance were highly correlated (R2 = 0.82), but mean clearance values were markedly different (mean +/- SEM, 28.70 +/- 0.01 and 37.07 +/- 1.29 ml/min, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Selective parathyroidectomy of the dog

Selective parathyroidectomy (PTX) is preferred to thyroparathyroidectomy (TPTX) when specific effects of parathyroid hormone depletion are being studied. However, because of the anatomic proximity of thyroid and parathyroid glands, TPTX often is performed, leaving animals depleted of thyroxine (T4) and calcitonin as well as parathyroid hormone (PTH). In the present study, six normal dogs had parathyroid tissue and about seven-eighths of thyroid tissue removed. This quantity of thyroid tissue was inadequate to maintain normal serum T4 concentrations, despite allowance of 168 days for thyroid recovery. Five of six dogs with reduced renal mass had successful selective PTX and normal serum T4 concentrations at 28 days, when one-half or more of thyroid tissue was spared. We conclude that with attention to the surgical technique, selective PTX can be achieved in a high percentage of dogs and sufficient thyroid tissue spared to maintain euthyroidism.

How the range effect contaminates control scores in studies of visual illusions

The relationship between mean control scores and mean experimental scores in 23 experiments on alignment illusions has been examined. Evidence is presented to show that, through the operation of the range effect, control scores are biased to a significant degree in the direction of experimental scores. The implications of this are considered, not only as regards the value of control scores in psychophysical studies, but also as further evidence of the dangers of within-subjects experimental designs when issues depend upon the values of extreme points in a range of values.

Acute graft-versus-host-like disease induced by transplantation of human activated natural killer cells into SCID mice

Whereas T lymphocytes are essential for the initiation of acute graft-versus-host disease (aGVHD), it is not at all clear whether they or other cells or noncellular factors actually mediate the characteristic lesions. This report describes the in vivo effects of human NK cells, T cells, and cytokines on the induction of aGVHD in 4 Gy sublethally irradiated C.B-17 scid/scid (SCID) mice. Human NK and T lymphocytes were obtained separately by antibody- and complement-mediated negative selection from the peripheral blood of normal donors and expanded in medium containing rIL-2 and irradiated autologous feeder cells. The characteristics of the two groups of cells were analyzed before injection into SCID mice. Cytofluorometric phenotyping demonstrated that 70-95% of NK-enriched cells expressed CD3-, CD16+, CD56+, and CD8-dim+; ninety-seven per cent of T cells expressed CD3+, TCR-alpha/beta+, CD4+, or CD8-bright+. Analysis of K562 and Daudi cultured target cell lines demonstrated 40-50% higher cytotoxicity by NK-enriched cells as compared with activated T lymphocytes. TNF-alpha cytokine production was greatly increased in activated NK cells (250 pg/ml) as compared with T cells (25 pg/ml) and fresh PBMC (12.5 pg/ml). IFN-gamma was increased in both NK and T cells. After i.v. injection of 1-5 x 10(7) cells into irradiated SCID mice, minor to severe skin lesions, diarrhea, and weight loss occurred in NK- but not the T cell-injected animals. In NK-injected animals, thinning and focal loss of epithelium with pyknotic nuclear change and degeneration and loss of skin appendages were observed. Single cell necrosis, crypt abscess formation, and loss of glandular epithelium developed in the colon of NK but not in T cell-injected animals. These findings are very similar to allogeneic aGVHD in SCID mice injected with C57BL/6 mouse splenocytes. Immunohistological staining with anti-human CD56, CD3, TNF-alpha, and IFN-gamma antibodies demonstrated CD56+ cells in association with TNF-alpha and IFN-gamma secretion in the bowel of NK-injected animals. CD3+ cells were not found in the same tissues. These findings were not observed in T cell-injected and control mice. In summary, aGVHD-like lesions were induced by transplantation of xenogeneic human activated NK cells into SCID mice. We hypothesize that cytokines released from human NK cells play a central role in the pathogenesis of clinical aGVHD.

Plasma lipid, lipoprotein cholesterol, and apoprotein distributions in selected US communities. The Atherosclerosis Risk in Communities (ARIC) Study

The distributions of plasma lipids, lipoproteins, and apoproteins of 14,524 female and male black and white participants 45 to 64 years old in the Atherosclerosis Risk in Communities (ARIC) Study are presented. All specimens were analyzed at a central laboratory. Mean total cholesterol levels increased with increasing age across all ages from 204 to 229 mg/dL (12%) in women and from 208 to 213 mg/dL (2%) in men. Triglyceride levels increased with age in women, remained stable in men, and were higher in whites than blacks. High-density lipoprotein (HDL) cholesterol levels were higher in black and white women (range, 57 to 59 mg/dL) compared with black men (49 to 52 mg/dL) or white men (42 to 43 mg/dL). Cholesterol associated with HDL was distributed in a relatively constant proportion between HDL3 (70% to 76%) and HDL2 (24% to 30%) for all race/sex groups. Low-density lipoprotein (LDL) cholesterol levels increased with age in black (14.7%) and white (17.1%) women and in black (4.4%) and white (3.7%) men; more than 50% of all participants had LDL cholesterol levels > 130 mg/dL. Apoprotein A-I and B levels followed the same trends as HDL cholesterol and LDL cholesterol levels, respectively. Lipoprotein(a) [Lp(a)] levels were twice as high in blacks as in whites, and women's Lp(a) levels were higher than men's Lp(a) levels for each race. Menopause was associated with elevated total cholesterol, LDL cholesterol, apoprotein B, and Lp(a) levels, and hormone replacement medication use in postmenopausal subjects was associated with higher HDL cholesterol, triglyceride, and apoprotein A-I levels and lower LDL cholesterol, apoprotein B, and Lp(a) levels.

In vivo transport and excretion of corrosion products from accelerated anodic corrosion of porous coated F75 alloy

Corrosion of porous coated cobalt chromium specimens surgically implanted subcutaneously in hamsters was accelerated by application of a fixed anodic potential. Corrosion current measurements were utilized for prediction of metal ion release based on Faraday's law. Daily urine samples were collected pre- and post-stimulation, and, at animal sacrifice, organs and blood samples were taken for chemical analysis. By using in vitro release data from previous studies, and efficiency correction factors, the amount of metal ion release was calculated. The results demonstrated rapid and complete excretion of nickel and molybdenum. Most of the cobalt was excreted, with elevation of cobalt levels in liver, kidney, and lung. Chromium excretion was much lower due to significant red cell binding and in vivo storage, especially in the kidney and spleen.

Gonadal steroids regulate the expression of glial fibrillary acidic protein in the adult male rat hippocampus

This study demonstrates that gonadal steroids (estradiol, testosterone, dihydrotestosterone) can regulate the expression of glial fibrillary acidic protein in the adult male rat brain. Previously, we showed that castration of adult male rats increased glial fibrillary acidic protein messenger RNA in the hippocampus and that this increase was additive with the increase induced by deafferenting entorhinal cortex lesions [Day et al. (1990) Molec. Endocr. 4, 1995-2002 . We extended these effects of castration and entorhinal cortex lesion to glial fibrillary acidic protein, using immunoassays. Furthermore, we found regional differences in responses to castration and inhibited by sex steroids. In contrast, hypothalamic glial fibrillary acidic protein expression was inhibited by castration. Similar regional differences were also shown for astrocyte glial fibrillary acidic protein distribution by immunocytochemistry. The regional specificity of glial fibrillary acidic protein expression after castration and sex steroid replacement is pertinent to the role of astrocytes in synaptic plasticity in unlesioned adults as well as in responses to lesions where the steroid milieu has been shown to influence sprouting.

Role of natural killer cells in the pathogenesis of human acute graft-versus-host disease

Clinical acute graft-versus-host disease (aGVHD) was correlated with alterations in PBL phenotype and skin immunohistology in 52 patients transplanted with HLA-identical bone marrow. Concurrent with the emergence of aGVHD, there was a profound decrease in absolute number of CD3- T cells and an increase in CD3-CD16+, CD56+ (a subset of which coexpress CD8+ "dim") NK cells in the PBL. CD4+ T and CD20+ B lymphocytes failed to recover within 90 days in the patients with grades II-IV aGVHD. Ex vivo partial T cell depletion, in itself, did not significantly impair T cell recovery as compared to that in non-T-depleted recipients unless aGVHD occurred. Although leukocytic cellular infiltration in the skin was generally sparse, CD16+ NK lymphocytes were significantly increased in grades II-IV aGVHD. By contrast, there was no significant increase in CD3+, CD4+, or CD8+ lymphocytes in these lesions as compared to skin biopsies obtained from BMT patients without aGVHD or from normal skin. Taken together, these findings suggest that NK cells may be important in the pathogenesis of human aGVHD.

Production of recombinant Xenopus fibroblast growth factor receptor-1 using a baculovirus expression system

A baculovirus expression system has been used to express large quantities of full-length, biologically active Xenopus fibroblast growth factor receptor-1. Recombinant XFGFR-1 was purified to near homogeneity by a single step immunoaffinity purification procedure. The recombinant XFGFR-1 binds both FGF-1 and FGF-2 with high affinity. XFGFR-1 undergoes autophosphorylation principly on tyrosine residues in an immune-complex kinase assay. Thus, recombinant XFGFR-1 expressed in insect cells is biologically active and suitable for structural and functional analysis.