Cocaine in decomposed human remains

From March 1988 through March 1990, at the Philadelphia Medical Examiner's Office toxicology laboratory, samples from 77 decomposed human bodies were tested for the presence of cocaine, employing gas chromatography/mass spectrometry (GC-MS). The material analyzed included decomposed soft tissue, bloody decomposition fluid, mummified tissue, maggots, and beetle feces. Twenty-two cases (28.6%) were positive for cocaine, many of these cases in states of advanced decomposition. These findings indicate the usefulness of testing decomposed tissue for cocaine in all cases where its presence is suspected. This is contrary to what might be expected, since cocaine is generally labile and rapidly broken down by both enzymatic and nonenzymatic mechanisms.

Early renal medullary hypoxic injury from radiocontrast and indomethacin

We evaluated the acute changes in cortical and outer medullary oxygen tension and the alterations in renal function and morphology within the first 90 minutes after the administration of indomethacin and iothalamate to anesthetized Sprague-Dawley rats. Both agents were found to produce marked and protracted outer medullary hypoxia averaging 12 +/- 4 and 9 +/- 2 mm Hg, respectively (mean +/- SE). Given together to salt depleted uninephrectomized rats they produced an early hypoxic injury localized selectively in the outer medulla. This lesion progressed from 3 +/- 1% of medullary thick ascending limbs (mTALs) at 15 minutes to 22 +/- 7% at 24 hours. Condensed "dark" cells were observed at 15 minutes, probably representing a type of early injury. Residual red cell mass, quantified in the outer medullary vasculature of perfusion-fixed kidneys and presumably reflecting stasis, was substantially increased in iothalamate treated rats. Red cell mass in the interbundle zone correlated with mTAL necrosis. Taken together, these results show an early period of medullary hypoxia, accompanied by a selective injury to mTALs in the central interbundle zone with apparent stasis. These findings contrast sharply with the ischemia-reflow pattern of renal damage and emphasize the important role of medullary hypoxia in the genesis of acute renal failure in this model.

Phase I trial of H65-RTA immunoconjugate in patients with cutaneous T-cell lymphoma

H65-RTA is an immunoconjugate that consists of the A chain of ricin (RTA), a ribosomal-inhibiting protein, coupled to a murine monoclonal antibody (H65) directed against the pan-T-cell antigen CD5. The CD5 antigen is heterogeneously expressed on cutaneous T-cell lymphoma tumor cells, but is not expressed on normal cells except lymphocytes. A phase I trial was therefore conducted in which 14 patients with cutaneous T-cell lymphoma progressive on other therapies were treated with up to three cycles of H65-RTA. The maximal tolerated dose (MTD) of H65-RTA was 0.33 mg/kg/d administered intravenously for 10 days as defined by dyspnea at rest at higher doses. Other reversible side effects included myalgia, mild hypoalbuminemia with weight gain, pedal edema, fatigue, fevers, and chills. Six patients received more than one cycle of H65-RTA without increased side effects compared with the first cycle. Pharmacokinetic analysis showed that peak serum drug levels were dose-dependent, and ranged from 1.13 to 5.56 micrograms/mL, with a terminal half-life ranging from 1.0 to 2.9 hours. The development of antibodies against the immunoconjugate was associated with a lower peak drug level, but not with enhanced side effects. Partial responses lasting from 3 to 8 months were documented in four patients. Three of the responding patients received more than one cycle of H65-RTA in the presence of anti-immunoconjugate antibodies. The results from this phase I trial suggest that H65-RTA is an active drug in the treatment of cutaneous T-cell lymphoma. The immunoconjugate may be safely administered repeatedly, even in the presence of anti-immunoconjugate antibodies, with responses noted. Additional studies at the MTD are needed to define the response rate in this disease.

Role of nitric oxide in renal medullary oxygenation. Studies in isolated and intact rat kidneys

We investigated the role of the endothelial-derived relaxing factor nitric oxide (NO) in the homeostasis of O2 supply to the renal medulla, a region normally operating on the verge of hypoxia. Sensitive Clark-type O2 microelectrodes were inserted into renal cortex and medulla of anesthetized rats. The inhibitor of NO formation, L-NG-monomethylarginine (LNMMA), while increasing blood pressure and reducing renal blood flow, decreased medullary pO2 from 23 +/- 3 mmHg to 12 +/- 3 (P less than 0.001), with no change in the cortex. These responses were promptly reversed by L-arginine, which bypasses the LNMMA blockade. In isolated rat kidneys, LNMMA reduced perfusion flow without altering glomerular filtration rate, and augmented deep medullary hypoxic injury to thick ascending limbs from 68 to 90% of the tubules (P less than 0.02). These changes were prevented by L-arginine. Nitroprusside had a protective effect upon thick limb injury. Finally, in a previously reported model of radiocontrast nephropathy (1988. J. Clin. Invest. 82:401), LNMMA increased the severity of renal failure (final plasma creatinine from 2.3 +/- 2 mg% to 3.4 +/- 3, P less than 0.005) and the proportion of damaged thick limbs (from 24 +/- 6% to 53 +/- 9, P less than 0.01). Nitrovasodilatation may participate in the balance of renal medullary oxygenation and play an important role in the prevention of medullary hypoxic injury.

Protective action of glycine in cisplatin nephrotoxicity

Because glycine is cytoprotective for kidney cells in vitro, we investigated its possible action in vivo to protect rats against cisplatin nephrotoxicity, a well-established experimental model of renal tubular injury. Glycine was infused at a dose of 1 mmol per 100 g body weight per hour for 75 minutes, starting 15 minutes before cisplatin, 5 mg per kg, was injected intravenously. Plasma concentration of glycine rose to 3.5 mmol per liter at the time cisplatin was injected. These rats were compared with cisplatin-treated animals treated with L-alanine or with isotonic saline. After five days plasma creatinine of saline-treated rats given cisplatin had risen threefold to 2.6 +/- 1.5 mg per 100 ml (mean +/- SD), as creatinine clearance fell to 25% of baseline (0.14 +/- 0.05 ml/min/100 g). Morphological evaluation disclosed extensive damage involving all S3 segments in the outer medulla as well as the medullary rays of the cortex. In contrast, in rats treated with glycine, plasma creatinine rose only to 1.2 +/- 0.2 mg/100 ml and creatinine clearance was maintained at 75% of baseline (0.35 +/- 0.05 ml/min/100 g). Glycine also attenuated the weight loss, polyuria, increased fractional excretion of sodium and potassium, decreased urinary osmolality, and renal glycosuria observed in control, saline-treated rats after cisplatin, while substantially decreasing the percentage of S3 tubules with evident morphological injury. Renal platinum content was unaffected by glycine. The administration of L-alanine or the delayed infusion of glycine, starting one hour after cisplatin was given, did not prevent cisplatin toxicity.(ABSTRACT TRUNCATED AT 250 WORDS)

Structure, bioactivity, and cellular localization of myomodulin B: a novel Aplysia peptide

Important insights into mechanisms by which neuromuscular activity can be modulated have been gained by the study of experimentally advantageous preparations such as the ARC neuromuscular system of Aplysia. Previous studies have indicated that one source of modulatory input to the ARC muscle is its own two motor neurons, B15 and B16. Both of these neurons synthesize multiple peptide cotransmitters in addition to their primary neurotransmitter acetylcholine (ACh). Peptides present in the ARC motor neurons include SCPA, SCPB, buccalin A and B, and myomodulin A. We have now purified a novel neuropeptide, myomodulin B, which is structurally similar to myomodulin A. Myomodulin B is present in two identified Aplysia neurons that contain myomodulin A; the ARC motor neuron B16 and the abdominal neuron L10. Ratios of myomodulin A to myomodulin B are approximately 6:1 in both cells. Like myomodulin A, myomodulin B potentiates ARC neuromuscular activity; it acts postsynaptically, and increases the size and relaxation rate of muscle contractions elicited either by motor neuron stimulation or by direct application of ACh to the ARC. When myomodulin A is applied to the ARC in high doses (e.g., at about 10(-7) M), it decreases the size of motor neuron-elicited muscle contractions. This inhibitory effect is never seen with myomodulin B. Thus, despite the structural similarity between the two myomodulins, there exists what may be an important difference in their bioactivity.

Right ventricular function in severe non-ischaemic mitral insufficiency

Mitral insufficiency (regurgitation) is a disease of both ventricles. To determine the pathophysiological implications and clinical value of assessment of right ventricular function in this disease, right ventricular ejection fraction was determined by radionuclide cineangiography (r = 0.73, P less than 0.01, vs contrast angiography, n = 30) in patients with severe, non-ischaemic mitral regurgitation. Among 31 patients with isolated mitral regurgitation treated medically, five died, all within 2 years of follow-up; all five were among the eight patients with left ventricular ejection fraction less than or equal to 45% (lower limit of normal), and among the six patients with right ventricular ejection fraction less than or equal to 30% (almost invariably associated with at least mild pulmonary hypertension). During the same period, valve replacement was performed in 22 patients with isolated mitral regurgitation; among the six patients with right ventricular ejection fraction less than or equal to 30% before operation, only one died (P less than 0.05), indicating the risk-mitigating effect of valve replacement. Among eight pre-operative patients with combined mitral and aortic regurgitation, four died within 7 years after double valve replacement; all patients with right ventricular ejection fraction during exercise less than 20% died. After mitral valve replacement for isolated mitral regurgitation, right ventricular ejection fraction improved rapidly (average 8% in less than 1 year (P less than 0.05); 3% more at 3 years after operation (P less than 0.05)). Post-operative symptom persistence was predictable from ventricular ejection fraction before operation less than 30% (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Autoimmune enteropathy and nephropathy with circulating anti-epithelial cell antibodies

We describe a child with circulating anti-epithelial cell antibodies, autoimmune enteropathy with intestinal villous atrophy, and membranous glomerulonephritis. The patient had persistent diarrhea at 6 months of age, and a small bowel biopsy showed active enteritis, villous atrophy, and crypt hyperplasia. When the patient was, 10 months of age, nephrotic syndrome developed because of membranous glomerulonephritis. Results of tests for circulating immune complexes were negative. Indirect immunofluorescence studies revealed a circulating antibody directed against renal epithelial cells. Circulating antibodies directed against normal small intestine epithelial cells were also detected by the immunoperoxidase technique. Western blot and immunoprecipitation identified a 55-kd antigen, in both small bowel and kidney, that reacted with an antibody in the patient's serum. High-dose prednisone therapy induced a clinical remission, resolution of the small bowel injury, and diminished serum anti-epithelial cell antibodies; after dose reduction, clinical relapse occurred with villous atrophy and reappearance of anti-epithelial cell antibodies. When the patient was 45 months of age, persistent diarrhea recurred despite intravenous administration of corticosteroids, cyclosporine, and total parenteral nutrition. Autoantibodies to a 55-kd epithelial cell protein are temporally related to the development of enteropathy and nephropathy. Study of similar patients is needed to determine the role of such antibodies in this disorder.

Ventricular fibrillation threshold is influenced by left ventricular stretch and mass in the absence of ischaemia

STUDY OBJECTIVE

Ischaemic heart disease is known to contribute to the development of ventricular arrhythmias. However, the role of non-ischaemic variables has been less well defined. We therefore studied the effect of myocardial stretch and ventricular mass on the vulnerability of the rat heart to ventricular fibrillation. DESIGN AND EXPERIMENTAL MATERIAL: Two groups of rat hearts were studied in an isolated buffer perfused apparatus: group I, mature female animals with an average dry left ventricular weight of 73 mg and group II, a group of retired breeders with an average left ventricular weight of 122 mg. Hearts performed isovolumetric work at either low (0 mm Hg) or high (20 mm Hg) left ventricular end diastolic pressures.

MEASUREMENTS AND MAIN RESULTS

Ventricular fibrillation was provoked by trains of ventricular extrastimuli delivered at increasing current until development of the arrhythmia. The current required to provoke ventricular fibrillation decreased in both groups at the high left ventricular end diastolic pressure and the larger hearts in group II were more vulnerable to ventricular fibrillation than those in group I. The decrease in ventricular fibrillation threshold occurred in the absence of an increase in myocardial lactate production or a decrease in endocardial to epicardial flow ratios.

CONCLUSIONS

This study thus identified two variables, myocardial stretch and ventricular mass, which influence the development of ventricular fibrillation and which are independent of myocardial ischaemia in this animal model. These observations may be relevant to an understanding of the increased incidence of lethal arrhythmias which occur in patients with dilated cardiomyopathies.

Passive inhalation of free-base cocaine ('crack') smoke by infants

Cocaine is one of the most widely abused substances in the United States, in part due to the availability of its inexpensive alkaloidal free-base form, "crack". A variety of medical complications, including sudden death, are known to occur in the adult-user population, regardless of the route of cocaine administration. We report 16 cases of infant death registered by the Philadelphia (Pa) Medical Examiner's Office over a 2-year period (1987 through 1989), where toxicologic analyses revealed the presence of cocaine and/or its metabolite, benzoylecgonine. Scene investigation documented that these infants, shortly before death, had been exposed to environments that contained the smoke from crack. We conclude that the route of cocaine administration in this infant population was the passive inhalation of crack smoke. It is possible that the cocaine may have contributed to the death of these infants. Thus, in addition to the adult users, infants and children exposed to environments where crack is smoked may inhale cocaine and potentially suffer from its adverse effects.

Effect of glycine on medullary thick ascending limb injury in perfused kidneys

The addition of 2 mM glycine to the recirculating perfusate of isolated perfused rat kidneys almost completely prevented the severe morphological injury to tubular cells lining the medullary thick ascending limb (mTAL) that normally develops in this preparation. Glycine was similarly effective in reducing mTAL injury associated with hypoxic perfusion, indomethacin and amphotericin. Fractional reabsorption of sodium was increased with glycine, without any change in perfusate flow to the whole kidney and without consistent improvement in GFR. L-alanine demonstrated a similar though less pronounced cytoprotective action, but glutamine, cysteine, glutamate, cysteine plus glutamate, 1-serine and 4-aminoisobutyric acid all had little or no effect in preventing severe mTAL injury. The protective effect of glycine was unimpaired by the arginine analogue NG-monomethyl-l-arginine (L-NMMA), suggesting that the endothelial-derived relaxing factor, NO, was not involved. The action of glycine was not reduced by the addition of a substrate (benzoate) or a product (hippurate) of the glycine N-acyltransferase reaction. Glycine did not depress the respiration of dispersed mTALs prepared from rat kidneys. The cytoprotective effect of glycine in the mTAL of perfused kidneys, shared with l-alanine, appears to be relatively specific for these amino acids and probably unrelated to a diminution in cell work.

Experimental nephrotoxicity of the radiocontrast agents iohexol, ioxaglate, and iothalamate. An in vitro and in vivo study

The authors compared the renal toxicity of the low osmolality radiocontrast agents, iohexol and ioxaglate, and the ionic agent, iothalamate, at equivalent iodine dose, using experimental models in vitro and in vivo. In isolated perfused rat kidneys, all agents induced comparable biphasic hemodynamic changes, associated with similar declines in glomerular filtration rate (GFR) and tubular necrosis. In two different in vivo models (using multiple insults combined with the administration of radiocontrast), iothalamate appeared to induce more severe morphologic injury. Despite similar nephrotoxic potential in vitro, the newer radiocontrast agents, iohexol and ioxaglate, cause in vivo less renal injury than iothalamate in the experimental models.

Individual variability in the perception of cues to place contrasts in initial stops

Synthetic continua of two minimal pairs, BAIT-DATE and DATE-GATE, closely modeled on natural utterances by a female speaker, were presented to a group of 16 listeners for identification in full-cue and reduced-cue conditions. Grouped results showed that categorization curves for full- and reduced-cue conditions differed significantly in both contrasts. However, an averaging of results obscures marked variability in labeling behavior. Some listeners showed large changes in categorization between the full- and reduced-cue conditions, whereas others showed relatively small or no changes. In a follow-up study, perception of the BAIT-DATE contrast was compared with the perception of a highly stylized BA-DA continuum. A smaller degree of intersubject and between-condition variability was found for these less complex synthetic stimuli. The amount of variability found in the labeling of speech contrasts may be dependent on cue salience, which will be determined by the speech pattern complexity of the stimuli and by the vowel environment.

Electrode placements for cochlear implants: a review

Of the variety of different sites that have been proposed and used for cochlear implants, only two are now seeing widespread use. For single-channel electrodes, it appears that a placement at the round window, or just inside it, leads to no disadvantages (and perhaps some advantages) over deeper insertions. For multichannel implants, it appears that intra-cochlear electrodes are, generally speaking, preferable to extra-cochlear ones in a variety of ways, especially as the early fears about the dangers of intra-cochlear placement now seem exaggerated. One way in which extra-cochlear approaches may play an important accessory role in multichannel intra-cochlear implants is in allowing access to the apical end of the cochlea where residual nerve survival is likely to be best. Special considerations may apply for groups of patients who until recently have been implanted relatively infrequently--adults with significant residual hearing and children.

Residual frequency selectivity in the profoundly hearing-impaired listener

The extent to which auditory frequency analysis is retained in profoundly hearing-impaired listeners has major implications for hearing aid design. We have measured simplified psychoacoustic tuning curves in nine such listeners, using sinusoidal probes at 125 and 250 Hz, and 80-Hz wide narrow-band noise maskers. Two listeners showed PTCs at 125 and 250 Hz whose shapes were independent of probe frequency and parallel to their absolute thresholds, indicating the complete absence of frequency selectivity. Seven listeners showed evidence of frequency selectivity at 125 or 250 Hz or at both frequencies; at 250 Hz, frequency selectivity was evident in the six listeners whose 250-Hz hearing level was 95 dB or less, but not in the listeners with 250 Hz hearing levels above 95 dB. Where conventional 'v'-shaped PTCs were observed, estimated 3-dB auditory filter bandwidths were two to three times larger than those typically found in normal listeners. Notched-noise masking results at 250 Hz from the least hearing-impaired listener gave an estimated 3-dB bandwidth in reasonable agreement with that from the same listener's PTC data. Listeners who retain some frequency selectivity are able to make some use of first formant information in vowel identification, and preliminary results from one patient showed the ability to distinguish a variety of noise spectra. Both of these abilities could be of potential importance as a basis for the recoding of speech spectral patterning through stimulation matched to the listener's residual frequency selectivity.

Influence of endogenous prostaglandins on mTAL injury

We altered renal prostaglandin production by isolated rat kidneys in several ways to see if this would influence the susceptibility of cells lining the medullary thick ascending limb to injury. Rats were fed a diet containing either safflower oil (high in linoleic acid) or fish oil (low in arachidonate precursors) as a source of fat. After 90 min of perfusion, the kidneys of rats fed safflower oil showed only 32.7 +/- 6.7% of medullary thick ascending limb cells near the inner medulla with severe damage, whereas the same zone in perfused kidneys of rats fed fish oil showed 96.6 +/- 1.3% severely damaged cells (P less than 0.01). The protection afforded by safflower oil was accompanied by a doubling of urinary excretion of PGE2 and 6-keto-PGF1 alpha, and was eliminated by indomethacin, which suppressed prostaglandin synthesis. Perfusion with bradykinin also greatly increased prostaglandin excretion and reduced severe medullary thick ascending limb damage in the deepest zone of the outer medulla from 51.3 +/- 6.6% in controls to 28.5 +/- 5.9% (P less than 0.02). The protection provided by bradykinin was also completely reversed by indomethacin. The results suggest that endogenous prostaglandins serve a protective function against hypoxic injury for cells of the medullary thick ascending limb.

Transdermal versus subcutaneous leuprolide: a comparison of acute pharmacodynamic effect

Transdermal administration of peptides has been limited by the barrier properties of the skin. We compared the acute luteinizing hormone (LH) response to subcutaneous and transdermal administration of an LH-releasing hormone agonist (leuprolide). Eighteen volunteers received 5 mg leuprolide added to electrically powered patches delivering a current of 0.22 microA (transdermally). One week later, they received a 5 mg subcutaneous dose. LH response was measured. The area under the curve for LH response, maximum LH response, and time to maximum LH response were similar. Time to first response was shorter (147 +/- 108 minutes [transdermally] and 73 +/- 74 minutes [subcutaneously]; p less than 0.05), and the area under the curve for the first 150 minutes was greater (3655 +/- 2246 mIU.min/ml [transdermally] and 8666 +/- 4067 mIU.min/ml [subcutaneously]; p less than 0.05) for subcutaneous delivery. No major adverse effects were seen. This electrically powered transdermal technique merits further study.

Reduction of CFUs in high-speed handpiece water lines over time

Many methods are being investigated for reducing bacteria in the high-speed water lines of dental units. One of these is flushing water through the water lines prior to use. The objective of this study was to determine the actual change over time in the number of CFUs during flushing. Four consecutive samples were collected over time from the water lines of 20 different dental units that had been in disuse for over 48 hours. Next, autoclaved handpieces were connected and two additional samples were obtained. After culturing and determining CFUs per ml, data were analyzed to determine differences between samples. There were significant reductions between the first and second, second and third, third and fourth samples prior to adding the handpiece. There were no significant differences in the next two samples obtained after adding the handpiece.

Hypercalcemic nephropathy: chronic disease with predominant medullary inner stripe injury

Because of the recently observed augmentation of medullary hypoxic injury by calcium in isolated perfused rat kidneys (Kidney Int 34:186-194, 1988), renal morphology of chronic, prolonged hypercalcemia was investigated in vivo. Rats were treated with repeated injections of vitamin D2 (400,000 units/week) for two to eight weeks. Chronic elevation of plasma calcium from 2.1 to 2.8 mmol/liter (P less than 0.001) was associated by a fall in maximal urine osmolality with no change in glomerular filtration rate. The most significant morphological alterations occurred in the inner stripe of the outer medulla; these changes were characterized by a sequence of active injury with subsequent destruction and atrophy of the medullary thick ascending limbs, fibroblastic and lymphocytic infiltration, and secondary dilatation of collecting ducts. Similar changes occurred in the medullary rays. These alterations were accompanied by increased renal prostanoid production and a predisposition to acute kidney failure from indomethacin. Because of its selective occurrence in zones of poorest oxygen supply, this inner stripe injury may derive from vulnerability to hypoxia and may play a role in some chronic nephropathies.

Angiotensin II augments medullary hypoxia and predisposes to acute renal failure

The effects of angiotensin II (AII) upon medullary hypoxic injury and kidney function were investigated in vitro and in vivo. Synthetic AII added to perfusate of isolated rat kidneys reduced perfusion flow from 48 +/- 2 ml min-1 (+/- SE) to 19 +/- 1 (P less than 0.001) without altering glomerular filtration rate (GFR), raising filtration fraction from 1% to 3% (P less than 0.001). AII-extended hypoxic injury to medullary thick ascending limbs (mTAL) from 66 +/- 4% of tubules to 79 +/- 3 (P less than 0.05) in correlation with filtration fraction (r = 0.8, P less than 0.001). Addition of indomethacin (10(-4) mol l-1) further extended medullary hypoxic damage to 89 +/- 2% of mTAL (P less than 0.001). Uninephrectomized rats kept in metabolic cages were given AII by continuous infusion (0.1-0.8 microgram min-1) and indomethacin (10 mg kg-1 day-1) for 24 h. Creatinine clearance declined from 1.3 +/- 0.1 ml min-1 to 0.6 +/- 0.06 (P less than 0.001). Morphological examination revealed either selective necrosis of mTAL (in 12 +/- 4% of tubules) or luminal collapse (in 63 +/- 8%). Both necrosis and collapse correlated inversely with creatinine clearance and with each other (r = -0.5, P less than 0.001), the latter correlation suggesting protection from hypoxic injury by cessation of solute delivery. By increasing filtration fraction and decreasing blood flow, AII decreases renal oxygen supply while maintaining oxygen consumption for solute reabsorption. AII may predispose to acute renal failure by augmenting medullary hypoxia.