A 7-day intravenous toxicity study and neurotoxicity assessment of pyridorin in Sprague-Dawley rats

Pyridorin®, a naturally occurring metabolite of vitamin B6 that inhibits and scavenges reactive oxygen species, is being developed as a potential therapeutic for acute kidney injury. An investigational new drug application (IND) was opened for Pyridorin in support of its ongoing oral drug clinical development program. Currently, a Pyridorin intravenous (IV) formulation is being developed for use in surgical patients. To support the IND for Pyridorin, a full battery of nonclinical Good Laboratory Practice compliant studies was performed with no neurological or behavioral signs of toxicity seen following oral or IV administration of pyridoxine dihydrochloride (the active ingredient in Pyridorin). However, excessive ingestion of vitamin B6 has been reported to cause neurotoxic syndrome in humans. Therefore, under Food and Drug Administration recommendation, a 7-day IV study in rats was conducted to further evaluate the drug’s potential to cause neurotoxicity. Blood plasma samples indicated that exposure to pyridoxamine dihydrochloride and its metabolites, pyridoxal, pyridoxine, and 4-pyridoxic acid was linearly dose proportional and independent of gender. At doses of up to 200 mg/kg/day pyridoxine dihydrochloride, no treatment-related effects were seen in rats, providing further evidence for the absence of pyridoxine dihydrochloride-related changes in the nervous system. A no observed adverse effect level of 200 mg/kg/day was identified for this study.

Serial stellate ganglion blocks for intractable postherpetic itching in a pediatric patient: a case report

BACKGROUND

While intractable itching may be rarely associated with postherpetic neuralgia, it can have catastrophic complications if present.

METHOD

We highlight a severe case of postherpetic itching in a 10-year-old male with Fanconi's and aplastic anemia, refractory to conventional treatments and requiring intravenous sedation.

RESULTS

Our use of 3 sequential stellate ganglion blocks with 5.5 mL of 0.25% bupivacaine provided significant improvement of the symptoms for 4 months after the last procedure.

CONCLUSION

Although further evaluation is needed, we feel that novel use of sympathetic blockade may provide treatment for intractable itching. Highlighted is the possible influence of the sympathetic system in the pathophysiology of postherpetic itch.

IMPLICATION

The use of serial stellate ganglion blocks may be a treatment option for patients with intractable itching and postherpertic neuralgia of the neck and arm region. This technique may lead to more permanent solutions such as pulse radiofrequency lesion or chemical neurolysis of sympathetic ganglions for postherpetic itch.

The effect of digital image resolution and compression on anterior eye imaging

AIM

To determine the theoretical and clinical minimum image pixel resolution and maximum compression appropriate for anterior eye image storage.

METHODS

Clinical images of the bulbar conjunctiva, palpebral conjunctiva, and corneal staining were taken at the maximum resolution of Nikon:CoolPix990 (2048x1360 pixels), DVC:1312C (1280x811), and JAI:CV-S3200 (767x569) single chip cameras and the JVC:KYF58 (767x569) three chip camera. The images were stored in TIFF format and further copies created with reduced resolution or compressed. The images were then ranked for clarity on a 15 inch monitor (resolution 1280 x 1024) by 20 optometrists and analysed by objective image analysis grading. Theoretical calculation of the resolution necessary to detect the smallest objects of clinical interest was also conducted.

RESULTS

Theoretical calculation suggested that the minimum resolution should be > or = 579 horizontal pixels at 25x magnification. Image quality was perceived subjectively as being reduced when the pixel resolution was lower than 767 x 569 (p<0.005) or the image was compressed as a BMP or <50% quality JPEG (p<0.005). Objective image analysis techniques were less susceptible to changes in image quality, particularly when using colour extraction techniques.

CONCLUSION

It is appropriate to store anterior eye images at between 1280 x 811 and 767 x 569 pixel resolution and at up to 1:70 JPEG compression.

Continuous-fiber preform reinforcement of dental resin composite restorations

OBJECTIVES

Direct-filling resin composites are used in relatively small restorations and are not recommended for large restorations with severe occlusal-stresses. The aim of this study was to reinforce composites with fiber preforms, and to investigate the effects of layer thickness and configurations on composite properties. It was hypothesized that fiber preforms would significantly increase the composite's flexural strength, work-of-fracture (toughness) and elastic modulus.

METHODS

Glass fibers were silanized, impregnated with a resin, cured, and cut to form inserts for tooth cavity restorations. Also fabricated were three groups of specimens of 2mm x 2mm x 25 mm: a fiber preform rod in the center of a hybrid composite; a thin fiber layer on the tensile side of the specimens; and a thin fiber layer sandwiched in between layers of a hybrid composite. These specimens were tested in three-point flexure to measure strength, work-of-fracture and modulus. Optical and scanning electron microscopy were used to examine the restorations and the fiber distributions.

RESULTS

Microscopic examinations of insert-filled tooth cavities showed that the fibers were relatively uniform in distribution within the preform, and the inserts were well bonded with the surrounding hybrid composite. Specimens consisting of a fiber preform rod in the center of a hybrid composite had a flexural strength (mean (SD); n=6) of 313 (19)MPa, significantly higher than 120 (16)MPa of the hybrid composite without fibers (Tukey's at family confidence of 0.95). The work-of-fracture was increased by nearly seven times, and the modulus was doubled, due to fiber preform reinforcement. Similar improvements were obtained for the other two groups of specimens.

SIGNIFICANCE

Substantial improvements in flexural strength, toughness and stiffness were achieved for dental resin composites reinforced with fiber preforms. The method of embedding a fiber preform insert imparts superior reinforcement to restorations and should improve the performance of direct-filling resin composites in large restorations with high occlusal-loads.

Hydrolytic degradation of tyrosine-derived polycarbonates, a class of new biomaterials. Part II: 3-yr study of polymeric devices

The kinetics and mechanisms of in vitro degradation of tyrosine-derived polycarbonates, a new class of polymeric biomaterials, were studied extensively at 37 degrees C. These polymers carry an alkyl ester pendent chain that allows the fine-tuning of the polymer's material properties, its biological interactions with cells and tissue, and its degradation behavior. The polymer carrying an ethyl ester pendent chain, poly(DTE carbonate), has been established as a promising orthopedic implant material, exhibiting bone apposition when in contact with hard tissue. Tyrosine-derived polycarbonates are relatively stable and degrade only very slowly in vitro. Therefore, accelerated studies were conducted at 50 and 65 degrees C to observe the behavior of polymers during the later stages of degradation. Varying the pendent chain length affected the rate of water uptake, initial degradation rate, and physical stability of the polymeric devices. During the 3-yr study, the polymer degraded by random chain cleavage of the carbonate bonds, accompanied by a relatively small amount of pendent chain de-esterification. No mass loss was observed during this period at 37 degrees C, but mass loss was readily evident during the accelerated studies at 50 and 65 degrees C. Thus, it is reasonable to assume that mass loss will occur also at 37 degrees C, albeit only after extensive backbone carbonate cleavage and pendent chain ester hydrolysis. The dimension and surface area of the devices influenced the initial degradation rate, but did not significantly affect the overall rate of degradation. No evidence of "acid dumping" or the release of acidic residues found during the degradation of poly(D,L-lactic acid) were observed for this family of tyrosine-derived polycarbonates.

Beating heart surgery: why expect less central nervous system morbidity?

BACKGROUND

The incidence and etiology of brain dysfunction after conventional coronary artery bypass surgery using cardiopulmonary bypass (CPB) are reviewed.

METHODS

Stroke rates and incidences of cognitive dysfunction from various studies are considered. Mechanisms of injury including cerebral embolization as detected by transcranial Doppler and retinal angiography, and imaging-based evidence for postoperative cerebral edema, are discussed. Preliminary results from a prospective clinical trial assessing cognitive dysfunction after beating heart versus conventional coronary artery bypass with CPB are discussed.

RESULTS

Initial evidence for lower overall postoperative morbidity, and for a lower incidence of cognitive dysfunction specifically, after nonpump coronary revascularization is presented.

CONCLUSIONS

Beating heart surgery results in less potential for generation of cerebral emboli and appears to produce a lower incidence of cognitive dysfunction in both short- and intermediate-term postoperative follow-up periods as compared with conventional coronary artery bypass surgery using CPB.

Guamanian neurodegenerative disease: electrophysiologic findings

Amyotrophic lateral sclerosis (ALS), parkinsonism and/or dementia are highly prevalent among the Chamorro population of Guam. The incidence of Guamanian ALS has markedly declined in recent years, but these incidence figures may reflect underascertainment of subclinical disease. Guamanian Chamorro patients have not been systematically studied using modern clinical neurophysiological techniques. Electromyography (EMG: needle exam and nerve conduction studies) was used to study 29 patients with the major subtypes of Guamanian neurodegenerative disease, as well as 11 neurologically normal Guamanian Chamorro subjects. Central conduction was assessed by somatosensory evoked potentials (SEP's) in 16 patients. EMG evidence of peripheral neuropathy, (often subclinical) was found in 45% of Guamanian patients but no Chamorro control subjects. Diabetes mellitus, which is highly prevalent in this population, was present in some, but not all of these cases. Clinically unsuspected motor neuron disease was identified by EMG in only one of the 23 Guamanian patients with parkinsonism and/or dementia and in none of the 11 Chamorro control subjects. Two of seven patients with the clinical phenotype of Guamanian ALS had a more benign EMG pattern on the needle electrode exam with absence of fibrillation and fasciculation potentials. Three of 16 patients (all with parkinsonism and dementia) had mildly abnormal tibial SEP's. No patient had EMG evidence of myopathy or a defect of neuromuscular transmission. We conclude: (1) peripheral neuropathy may be a manifestation of Guamanian neurodegenerative disease; (2) the declining prevalence of ALS on Guam is not associated with the development of a subclinical form of motor neuron disease; (3) the substantial overlap of Guamanian ALS with parkinsonism-dementia reported in prior decades is no longer apparent; (4) abnormal central conduction, as assessed by tibial SEP's, is present in some patients with Guamanian parkinsonism-dementia.

Gaining a competitive edge through HIS technology

Streamlined procedures, fewer errors, improved consultation on patient care, and lowered costs are among the advantages cited by healthcare facilities that are using information technology in efforts to outpace their competitors. Technology ranging from executive information systems to medical record imaging can provide improved access to data and aid strategic decision making. Even so, the perceived benefits of a particular form of technology should not outweigh sound business planning.

Continuing education needs of board members, administrators, and health care personnel

Our society is becoming more aware of the basic fact that education is a lifelong process. The dynamic world in which we live requires that we continually update our knowledge and skills. Educational institutions that have traditionally viewed their mission as one of providing a sequence of courses leading to a specific degree are now expanding their role to include postgraduate nondegree offerings. The MIS area certainly ranks high among those fields that have a dynamic characteristic. Institutions with particular academic strength in this area can provide a needed service--and at the same time create a market niche for themselves--by developing and presenting continuing education programs in the area of MIS.

Dynamic internal compliance measurements of fresh and fixed artery

A new device is used to compare dynamic internal compliance of biologic vascular prostheses derived from bovine artery. These grafts were prepared using dialdehyde starch (DS), and a polyepoxy polyether compound (PC), as crosslinking agents. Internal compliance was measured using the Dynatek DCT1 Dynamic Compliance Tester, developed by Dynatek Laboratories. This device utilizes a variable speed DC motor coupled to miniature bellows, which displace a stroke volume controllable to within 0.5 microliter. The bellows displace fluid into and out of the graft, resulting in a sinusoidal change in internal pressure. Volumetric displacement is monitored by a linear voltage displacement transducer (LVDT) mounted on the motor coupling, whereas internal graft pressure is monitored by a miniature pressure transducer mounted on the closed end of the graft. For this series of experiments, a pressure range of 80-120 mmHg was used, with a cycle speed of 80 cycles/min. Preliminary results indicate that PC fixation of bovine artery results in a vascular graft with internal compliance somewhere between fresh tissue and DS fixation. This data confirms qualitative assessment. The DCT1 provides valuable comparative information on the dynamic internal compliance of vascular prostheses. These measurements reflect what occurs in the graft lumen, since they take into account wall compression and axial deformation. Further development is required to separate radial and longitudinal compliance components.

Performance of a longitudinally compliant PTFE vascular prosthesis in an ovine A-V fistula model

Nine chronic implants of 6 mm diameter vascular grafts were performed in an ovine model to compare the performance of the longitudinally compliant Ultraflex PTFE-Plus vascular prosthesis with that of the Gore-Tex reinforced expanded polytetra fluoroethylene (PTFE) graft. Implants were performed in the sheep neck as right carotid to left jugular arterio-venous (A-V) grafts. Grafts were explanted after 6 months unless they occluded earlier. The Ultraflex graft demonstrated superior handling characteristics during implant. Patency rate at 6 months was 60% (three of five) for the Ultraflex graft (experimental graft by Baxter Edwards, CVS Division, Irvine, CA), and 25% (one of four) for the Gore-Tex graft (WL Gore & Associates, Inc., Flagstaff, AZ). The Gore-Tex prosthesis had more calcification of the graft wall.

Expression and processing of recombinant human terminal transferase in the baculovirus system

Overproduction of human terminal transferase protein has now been accomplished by cloning the coding sequence of human terminal transferase into a baculovirus, where the expression of terminal transferase is under the control of the polyhedrin protein promoter. Two constructs were made, one producing a protein containing the entire terminal transferase fused to 12 amino acids from the NH2 terminus of the polyhedrin protein, and the other producing 58-kDa human terminal transferase. The terminal transferase levels expressed in cells infected with either recombinant baculovirus are around 10,000 units/10(7) cells at 48 h postinfection, about 200-fold greater than levels expressed in thymus and cultured lymphoblastoid cells. The chimeric polyhedrin/human terminal transferase protein produced in the infected insect cells has a molecular weight of about 60,000 while the nonfused recombinant human terminal transferase is identical in molecular weight to that present in human lymphoblastoid cells. Both forms of recombinant terminal transferase show immunological and enzymatic activity. When infected cells are pulse-labeled with [35S] methionine at 42-45 h postinfection, about 10% of newly synthesized protein is terminal transferase. Both forms of terminal transferase are phosphorylated in recombinant virus-infected cells as demonstrated by pulse-labeling infected cells with 32P-inorganic phosphate and isolation of labeled terminal transferase peptides by immunoprecipitation.

Evaluation of compliant and noncompliant PTFE vascular prostheses

Four chronic implants of 6 mm diameter grafts compare a new longitudinally compliant PTFE-composite vascular prosthesis (ULTRAFLEX PTFE-PLUS) with clinical grade microporous expanded polytetrafluoroethylene (PTFE). Implants were carried out in the ovine carotid-jugular position as A-V fistulae. All four grafts were subjected to sham dialysis punctures in identical fashion with 14-gauge needles. After 60 days the grafts were explanted and submitted for histologic evaluation. All four grafts were patent at explant. The compliant PTFE (ULTRAFLX PTFE-PLUS) lumen surface was thrombus free. Neointima lining at the proximal and distal anastomoses was similar in both test and controls. Tissue ingrowth and outer capsule formation were virtually identical. Foreign body reaction was minimal. Superior handling and self-sealing properties distinguished test from controls. Long term animal studies are in progress for vascular access and peripheral applications.

Nitrous oxide and human state-dependent memory

State-dependent effects of nitrous oxide on human memory were examined by administering serial and paired-associate learning tasks to subjects receiving 20 and 30% nitrous oxide or placebo. Nitrous oxide in 30% concentration impaired learning of both tasks. In addition, it produced an atypical form of asymmetric state-dependent memory; subjects who learned while receiving placebo and recalled while receiving nitrous oxide displayed the worst recall.

Prediction of the frequencies of restriction endonuclease recognition sequences using di- and mononucleotide frequencies

The calculation of probabilities of nucleotide sequences from the frequencies of dinucleotides is described. The dinucleotide and mononucleotide frequencies used can be obtained from nearest neighbor analysis or from databank sequences. If dinucleotide and mononucleotide frequencies from nearest neighbor analysis are used, probabilities for oligonucleotides can be calculated for genomes in which there is little or no sequence data. Within a given genome, a broad range of probabilities for hexanucleotide palindromes with the same base composition is predicted and shown (14).

Sequence and transcription of tRNAVal gene from Xenopus laevis

A DNA fraction enriched in tRNA genes has been prepared by CsCl density gradient centrifugation of Xenopus laevis DNA in the presence of actinomycin D. This DNA fraction was cut with the restriction endonuclease EcoRI and the fragments 800-900 base pairs in size were cloned into the plasmid pBR325. Recombinant DNAs were screened by hybridization to labeled tRNA and for the ability to support transcription in vitro. The entire sequence of one fragment was determined by sequencing the ends of an overlapping set of deletion fragments. A sequence homologous to tRNAVal from mammalian sources was found in this fragment and it was shown that this sequence corresponds to the region of the fragment that is transcribed. The cloned fragment was also transcribed in vivo after injection into X. laevis oocytes. The RNA that was synthesized in the oocytes was digested with ribonuclease T1 and the oligonucleotides were separated to produce a two-dimensional fingerprint. The results of the analysis of the oligonucleotides are consistent with the sequence determined for the tRNAVal gene. The X. laevis genome has 200-250 copies of the 892 base pair EcoRI fragment and additional copies of a 4100 base pair EcoRI fragment that each contain a tRNAVal gene. Digestion of X. laevis DNA with several other restriction endonucleases reveals that the cloned fragment that contains the tRNAVal gene is part of a longer sequence element that is tandemly repeated in the genome.

Expression of human terminal deoxynucleotidyl transferase in Escherichia coli

A cloned DNA fragment related to pT17 containing a partial cDNA sequence of human terminal deoxynucleotidyl transferase was used as a probe to screen for the full length cDNA sequence of the enzyme in a lambda gt11 library constructed from human lymphoblastoid KM-3 cDNA. A recombinant containing a 2068-base pair insert was isolated and recloned into the EcoRI site of the sequencing plasmic pUC-8 as two subclones, pT711 and pT106. DNA sequencing and hybridization studies showed that pT711 contains the pT17 sequence and an additional 172 upstream nucleotides. pT711 represents the coding sequence for the carboxyl half of the terminal transferase protein. pT106, containing a 965-base pair insert, hybridizes to the same mRNA as pT711 on Northern blots and contains an open reading frame that is in phase with the reading frame of the insert in pT711. Amino acid sequencing of the 58-kDa peptide of the calf thymus terminal transferase failed, indicating that the N terminus is blocked. N-Terminal sequencing of a 56-kDa form of the protein produced 24 amino acids corresponding to the translated human cDNA coding sequence starting at residue 398 of the insert in pT106 with 83% homology between bovine and human sequence. The initiation codon is assigned to an ATG sequence at nucleotide 329 of the insert in pT106. Comparison of the translated human terminal transferase sequence with peptides from the calf thymus enzyme showed that the homology between the human and bovine enzyme is better than 90% among 263 amino acids determined. The coding sequences in pT106 and pT711 were recloned into an expression plasmid pUC-19 downstream from the lac promoter and in phase with the coding sequence of the lac Z gene. Lysates of bacteria carrying the reconstructed coding sequence of human terminal transferase contain a fused protein of 60 kDa that reacts with rabbit antibody to terminal transferase on immunoblots and exhibits enzyme activity. Isolation of this fused protein from bacterial lysates with mouse monoclonal antibody to human terminal transferase produces the expected protein of 60 kDa.

Chromosome localization of the gene for human terminal deoxynucleotidyltransferase to region 10q23-q25

Complementary DNA clones representing the 3' half, the 5' half, and the entire coding region of the human terminal deoxynucleotidyltransferase gene (TdT; DNA nucleotidylexotransferase, nucleosidetriphosphate: DNA deoxynucleotidylexotransferase, EC 2.7.7.31) were used to screen a panel of mouse X human somatic cell hybrid DNAs to determine the chromosomal location of the human TdT gene. The results of the Southern transfer analysis of hybrid DNAs indicate that the gene for TdT is located on human chromosome 10. The in situ hybridization technique was then used to further localize the gene for TdT to region q23-q25 of human chromosome 10.

Molecular cloning of human terminal deoxynucleotidyltransferase

A cDNA of the human terminal deoxynucleotidyltransferase (TdT; "terminal transferase," EC 2.7.7.31) was isolated from a human lymphoblastoid cell cDNA library in lambda gt 11 by using immunological procedures. Four inserts containing 723 to 939 base pairs were recloned in pBR322 for hybridization and preliminary sequence studies. mRNA selected by hybridization to recombinant DNA was translated to a 58-kDa peptide that specifically immunoprecipitated with rabbit antibodies to calf terminal transferase and mouse monoclonal antibody to human terminal transferase. Blot hybridization of total poly(A)+ RNA from KM3 (TdT+) cells with nick-translated pBR322 recombinant DNA detected a message of about 2000 nucleotides, sufficient to code for the 580 amino acids in the protein. mRNA from terminal transferase- cells gave no signal in hybrid selection or RNA blot hybridization. The complete sequence of the 939-base-pair insert sequence was obtained from deletions cloned in pUC8. The DNA sequence contains an open reading frame coding for 238 amino acids, about 40% of the protein. Three peptides isolated by HPLC from tryptic digests of succinylated 58-kDa calf thymus terminal transferase were sequenced, providing 20, 18, and 22 residues of peptide sequence. A search of the translated sequence of the 939-base-pair insert shows three regions beginning after arginine that have greater than 90% homology with the sequence determined from the calf thymus terminal transferase peptides. These results provide unambiguous evidence that the human terminal transferase sequence has been cloned.

Information planning for the 1980's and 1990's

With the shift in reimbursement, new medical technology, and increased competition, hospitals must be managed more effectively. Management information systems are being developed to meet these new challenges. This article provides an overview of the types of information needed and outlines the development of a comprehensive information systems plan.

In utero exposure of bovine fetuses to polychlorinated biphenyls

Pregnant mature beef cows more than 6 mo from parturition were fed whole plant corn silage from either a silo (contaminated) that had been coated with a plastic containing polychlorinated biphenyls (Aroclor 1254) or from a silo (clean) that had not been coated with the plastic. In addition, a third group of cows was fed silage from the clean silo plus 200 mg Aroclor 1254 per head daily (added polychlorinated biphenyls). After 30 days on treatment, one cow from each of the three treatments had her fetus removed by Caesarean section for assay of liver, thyroid, and fat for polychlorinated biphenyls content. Tissue content of polychlorinated biphenyls for fetuses from cows fed clean silage, contaminated silage, or added polychlorinated biphenyls was (microgram/g): liver, 3.6, 4.7, and 54.1; thyroid, 2.3, 19.4, and 121.1; fat, .65, 18.1, and 130.6, indicating polychlorinated biphenyls cross the placenta readily. Cow milk (colostrum) contents of polychlorinated biphenyls on the 1st day following parturition for the three respective treatments were .54, 8.5, and 96.4 micrograms/g (clean silage, contaminated silage, and added polychlorinated biphenyls). Fetuses taken from cows that had been removed from polychlorinated biphenyl exposure for 6 mo reflected previous treatments of dams by increased fetal fat stores of polychlorinated biphenyls.

Dietary Aroclor 1254 in the milk fat of lactating beef cattle

Excretion in milk fat of Aroclor 1254 (a mixture of polychlorinated biphenyl) by mature beef cows (Hereford and Hereford cross) was studied. Three groups of 6 cows each were fed primarily a corn silage diet characterized by 1) clean silage (stored in an uncontaminated silo), 2) silage stored in a silo coated with a sealant containing Aroclor 1254, and 3) clean silage to which 200 mg Aroclor 1254 per head daily was added (approximately 2 to 3 mg/kg body weight per day). Treatments were started approximately 3 mo prior to parturition and extended 1 mo after parturition, at which time treatments were discontinued, and cows and nursing calves were placed on pasture. Milk was sampled in the period between parturition and 132 days after discontinuance of treatments. Fat from the milk of cows fed silage from the silo which had not been sealed with the Aroclor 1254 product contained .69 to 1.59 ppm Aroclor 1254 throughout the 164-day lactation. Fat from cows fed silage from the silo treated with the Aroclor 1254 sealant contained more than ten times as much Aroclor 1254 (15.7 to 18.4 ppm) for 32 days as compared with the controls and then dropped to one-half that figure through the 164th day. Fat from the milk of cows fed 200 mg Aroclor 1254 per day contained from 119 to 150 ppm through the first 32 days and then dropped to 39 to 51 ppm through day 164.

Acetaminophen overdose. 662 cases with evaluation of oral acetylcysteine treatment

Six hundred sixty-two consecutive patients with acetaminophen overdoses were evaluated. Those at risk on the basis of their acetaminophen blood levels, as plotted on the study nomogram, were treated with oral acetylcysteine. Statistically significant differences in severity of hepatic toxicity were observed between patients treated within 16 hours after ingestion and those treated between 16 and 24 hours after ingestion. No deaths occurred among patients treated within 24 hours of ingestion, except for one patient who was an alleged gunshot homicide. Seven percent of patients with plasma acetaminophen levels in the potentially toxic range and treated with acetylcysteine within ten hours of ingestion showed transient SGOT level elevations, whereas 29% of those treated between ten and 16 hours after ingestion and 62% of those treated between 16 and 24 hours after ingestion showed such transient toxicity. No consistent difference in hepatotoxicity could be demonstrated between those patients with a history of chronic alcohol use and those patients with no history of chronic alcohol use. Acute alcohol use resulted in less severe toxic reactions than in those patients without acute alcohol use.

Acetaminophen overdose. 662 cases with evaluation of oral acetylcysteine treatment

Six hundred sixty-two consecutive patients with acetaminophen overdoses were evaluated. Those at risk on the basis of their acetaminophen blood levels, as plotted on the study nomogram, were treated with oral acetylcysteine. Statistically significant differences in severity of hepatic toxicity were observed between patients treated within 16 hours after ingestion and those treated between 16 and 24 hours after ingestion. No deaths occurred among patients treated within 24 hours of ingestion, except for one patient who was an alleged gunshot homicide. Seven percent of patients with plasma acetaminophen levels in the potentially toxic range and treated with acetylcysteine within ten hours of ingestion showed transient SGOT level elevations, whereas 29% of those treated between ten and 16 hours after ingestion and 62% of those treated between 16 and 24 hours after ingestion showed such transient toxicity. No consistent difference in hepatotoxicity could be demonstrated between those patients with a history of chronic alcohol use and those patients with no history of chronic alcohol use. Acute alcohol use resulted in less severe toxic reactions than in those patients without acute alcohol use.

Large-aperture high-resolution x-ray collimator for the Solar Maximum Mission

A description is presented of a flight-qualified large-aperture 12 x 12-sec of arc angular resolution multigrid x-ray collimator developed for the Solar Maximum Mission (SMM) flat crystal spectrometer. This collimator, designed for the 1.4-22.4-A wavelength range, utilizes an optical bench/metering structure to align and support prealigned grid subassemblies. One advantage of this scheme is to provide ready access to the grid subassemblies for inspection and/or servicing. The optical bench is a lightweight, rigid, and stable aluminum honeycomb structure. Aluminum is a viable material choice in this application because of the good thermal control expected in the SMM instrument package. The grids are of a compound and bimetallic design, having 63.5-microm square holes on an 88.9-microm spacing in 8-microm thick gold, which is in turn supported by a 76-microm thick Invar grid having 600-microm square holes on a 739-microm spacing. The small apertures in the gold provide the 12-sec of arc collimation with the Invar grids providing wide angle off-axis blocking out to an ~35-min of arc view angle. The collimator has seven individual channels, four of a 5.1- x 10-cm area and three of a 1.3- x 10-cm area. Laboratory measurements gave an average angular resolution of 12.5-sec of arc FWHM with 0.259 transmission for the large area channels and 12.0 sec of arc and 0.200 transmission for the small area channels. A hypothetical perfectly aligned collimator would have 12.5-sec of arc resolution and 0.300 transmission. A thermal filter composed of two layers of ~1000-A thick aluminum prevents solar heating of the front collimator grids by absorbing longer wavelength radiation while passing most of the x radiation in the band of interest. The filter was flight qualified by passing a protoflight acoustic test environment of 147-dB total sound level, 20-microN/M(2) reference, for 1-min duration.

Characterization of two xenopus somatic 5S DNAs and one minor oocyte-specific 5S DNA

The somatic 5S DNA from X. borealis (Xbs 5S DNA) and X. laevis (Xis 5S DNA) and a minor oocyte-specific 5S DNA from X. laevis (Xit 5S DNA) have been purified, and individual repeating units have been cloned and sequenced. The two somatic 5S DNAs differ from the major oocyte 5S DNAs in having GC-rich spacers, homogeneous repeat lengths and no "pseudogenes." The somatic 5S DNAs from the two species have similar spacer sequences with differences due to single base changes and insertions/deletions. The spacer of the minor oocyte-specific 5S DNA (Xit) has the AT-rich sequence characteristic of the major oocyte 5S DNAs from X. laevis and X. borealis, and contains one duplication that has diverged approximately 40%. Like the somatic 5S DNAs, Xit 5S DNA has a homogeneous length repeat and a unique nucleotide sequence in its spacer. The presence of variable-length spacer regions in a multigene family correlates with variables numbers of a simple sequence in the spacer regions.

Marijuana and health: 1980

In this eighth edition of the Marihuana and Health Report several areas of recent developments in marijuana research are highlighted together with a summary of the scientific research accumulated through the end of 1979 concerning the drug's possible health implications.

A Molecular Orbital Study of the Stereochemistry of Pentacoordinated Aluminium

An attempt has been made to characterize the stereochemical requirements of an aluminium atom coordinated by five hydroxyl groups (AlO5H52-) within the framework of CNDO/2 molecular orbital formalism. Total energy surfaces calculated for this system as the valence angles are varied within the constraints of C2v symmetry clearly show the 'reaction coordinate' for the so-called Berry pseudo- rotation mechanism. With all Al-O and O-H bond lengths fixed at 1.84 and 1.00 Ǻ respectively, the activation energy for trigonal-bipyramidal/square-pyramidal interconversion is 7.1 kJ mol-1. In addition, the minimum energy O(axial)-Al-O(basal) angle for the square-pyramidal group is estimated to be c. 103.5°. When one bond is lengthened relative to the other four the trigonal-bipyramidal configuration is further stabilized, but approaches tetrahedral geometry. When one bond is shortened square-pyramidal geometry is stabilized and the minimum energy O(ax)-Al-O(bs) angle increases. With two bonds lengthened (or shortened) the favoured trigonal-bipyramidal configuration is the one with long bonds directed towards the axial positions and at no stage is there a stabilization of square-pyramidal geometry. These results agree with trends in calculated Mulliken bond overlap populations and with observed ratios of axial-to-basal bond lengths in suggesting that for trigonal- bipyramidal stereochemistry the axial bonds are weaker, whereas for square-pyramidal geometry the axial bond is stronger. Moreover, consideration of the total energy for various isomers of Al(OH)4F2- indicates that more electronegative substituents prefer to enter the apical and basal positions in a trigonal bipyramid and a square pyramld respectively. For a cluster Al2(OH)82-, consisting of two aluminium trigonal-bipyramidal groups sharing a common edge of variable length, an energy minimum (62.2 kJ mol-1 lower than the undistorted case) is found at a shared edge length of 2.246 A, 13 % shorter than for the undistorted polyhedron. The corresponding observed distance for a similar dimer in the mineral andalusite, Al2SiO5, is 2.247(7) Ǻ. Plots of minimum energy shared edge length against mean bond length for various clusters M2(OH)8n-, where M = Al or Mg, clearly demonstrate an essentially linear relationship between the two parameters consistent wlth trends observed for natural systems in which M = Co, Cu, Mn and Zn.

Selenium in milk from feeding small supplements

Supplements of 0, 1, 2, or 5 mg of selenium from sodium selenite fed per cow daily from 90 days prepartum through approximately 6 mo of lactation had no significant effect on selenium in milk of Hereford cows. Selenium in milk was assayed 2 to 3 days postpartum (average of .014 to .023 ppm) and approximately 3 mo post parturition (average of .016 to .021 ppm). The basal diet consisted of medium quality grass-legume hay (.069 mg/kg), ad libitum liquid supplement (.152 mg/kg), and 1.36 kg shelled corn (.018 mg/kg) starting in early lactation. Treatments of selenium were administered via free-choice liquid supplement.

Binding specificity of the juvenile hormone carrier protein from the hemolymph of the tobacco hornworm Manduca sexta Johannson (Lepidoptera: Sphingidae)

A series of analogues of insect juvenile hormone (four geometric isomers of methyl epoxyfarnesenate, several para-substituted epoxygeranyl phenyl ethers, and epoxyfarnesol and its acetate and haloacetate derivatives) was prepared to investigate the binding specificity of the hemolymph juvenile hormone binding protein from the tobacco hornworm Manduct sexta. The relative binding affinities were determined by a competition assay against radiolabeled methyl (E,E)-3,11-dimethyl-7-ethyl-cis-10,11-epoxytrideca-2,6-dienoate (JH I). The ratio of dissociation constants was estimated by plotting competitor data according to a linear transformation of the dissociation equations describing competition of two ligands for a binding protein. The importance of the geometry of the sesquiterpene hydrocarbon chain is indicated by the fact that the binding affinity is decreased as Z (cis) double bonds are substituted for E (trans) double bonds in the methyl epoxyfarnesenate series; the unepoxidized analogues do not bind. A carboxylic ester function is important although its orientation can be reversed, as indicated by the good binding of epoxyfarnesyl acetate. In the monoterpene series, methyl epoxygeranoate shows no affinity for the binding protein, but substitution of a phenyl or p-carbomethoxyphenyl ether for the ester function imparts a low, but significant affinity. These data taken together with earlier results indicate that the binding site for juvenile hormone in the hemolymph binding protein is characterized by a sterically defined hydrophobic region with polar sites that recognize the epoxide and the ester functions.

Purification and characterization of the carrier protein for juvenile hormone from the hemolymph of the tobacco hornworm Manduca sexta Johannson (Lepidoptera: Sphingidae)

The larval hemolymph of the tobacco hornworm, Manduca sexta, contains a carrier protein that binds specifically and with high affinity the juvenile hormone, an important regulator of insect development. This protein serves to transport the hormone and to protect it from the action of degradative enzymes during early larval stages. Using hemolymph from the last larval stage, we have isolated a pure carrier protein using acetone precipitation, gel filtration, ion exchange chromatography, and preparative isoelectric focusing. Gel filtration, polyacrylamide gel electrophoresis in sodium dodecyl sulfate, and equilibrium ultracentrifugation established that the carrier protein is a single chain polypeptide of approximately 28,000 daltons. The amino acid composition is unexceptional, and no evidence for hexosamine has been obtained. An ion exchange filter disc assay method was used to determine the formation of the complex between the carrier protein and isotopically labeled juvenile hormone. With this technique it was shown that each carrier protein binds one hormone molecule with a dissociation constant of 4.4 +/- 0.2 X 10(-7) M at 0 degrees.

Selenium content of feeds and effect of dietary selenium on hair and blood serum

A selenium depletion diet (.025 ppm selenium) was fed to two male Holstein calves for its effect on concentrations of selenium in serum. By 90 days, selenium in serum was depressed from .022 ppm to .013 ppm, and one of two calves had died of "possible white muscle disease." Repletion was rapid in that a diet containing .200 ppm selenium increased selenium in serum to .028 ppm within 2 wk. Dietary .280 ppm selenium increased it to .051 ppm in 1 wk. Eleven cows and eleven calves showed averages of .030 ppm in serum (range of .013 to .051 ppm) fed a diet of corn silage (.039 ppm) and supplement (.090 ppm). A sampling of feedstuffs showed a wide range of selenium among feedstuffs (.023 for corn cobs to 2.663 ppm for dried egg albumin) and a wide range within one type feedstuff (shelled corn, .017 to .219 ppm).

Total reduction of distorted echelle spectrograms: an automatic procedure

We describe a semiautomatic procedure for the reduction of high-dispersion echelle spectra recorded with an image tube. The spectra are traced with a computer-controlled microdensitometer that scans along the curved spectral orders. The curvature of each order is calculated approximately by a FORTRAN program from known grating and distortion parameters. A typical spectrum includes 25 orders (covering 1500 A) and is traced with a slit 0.012 A wide. To produce an atlas of intensity vs wavelength and to determine the equivalent widths of 300 lines currently require a day. We discuss the reduction procedures and time requirements in detail.

Effects of living conditions on drinking in the hooded rat

Drinking of rats living in the main colony room was compared to drinking of animals in isolation. Animals consume the major portion of their daily intake during the dark phase of the day and the correlation between drinking and dark-light ratio is more apparent for animals in isolation.