Smokeless tobacco extracts activate complement in vitro: a potential pathogenic mechanism for initiating inflammation of the oral mucosa

The use of smokeless tobacco has been linked to an increased incidence of inflammation of the buccal and gingival mucosa. However, the mechanisms by which smokeless tobacco initiates inflammation are not well understood. The complement cascade is a ubiquitous source of proinflammatory molecules and can be activated rapidly by a wide variety of agents. Therefore, the effect of smokeless tobacco on complement was investigated as a potential pathogenic mechanism for triggering inflammation of the oral mucosa. Aqueous extracts of loose leaf chewing tobacco (1S1), dry snuff (1S2), and moist snuff (1S3), added to normal human serum, depleted complement hemolytic activity in a dose-dependent manner. Experiments utilizing sera deficient in one specific complement component indicated that the smokeless tobacco-induced depletion of hemolytic activity was due largely to consumption of C3. Furthermore, assays designed to test the activity of the alternative pathway of complement clearly showed that all three extracts depleted the hemolytic activity of this pathway. Finally, all three smokeless tobacco extracts activated the alternative pathway since significantly elevated levels of the cleavage fragments iC3b and Bb were detected in extract-treated serum. High quantities of the classical pathway cleavage fragment C4d also were detected in serum treated with moist snuff (1S3). The results clearly demonstrate that smokeless tobacco extracts activate the alternative pathway and also suggest some measure of classical pathway activation. Activation of complement by smokeless tobacco may be a mechanism for initiating inflammation of the oral mucosa.

Telomerase activity in benign and malignant human thyroid tissues

Telomerase is a specialized ribonucleoprotein polymerase that directs the synthesis of telomerase repeats at chromosome ends. Accumulating evidence has indicated that telomerase is stringently repressed in normal human somatic tissues but reactivated in cancers and immortal cells, suggesting that activation of telomerase activity plays a role in carcinogenesis and immortalization. In this work, the status of telomerase activity during the development of human thyroid cancer was determined using telomeric repeat amplification protocol (TRAP) in 14 nodular hyperplasia, 14 adenomas, 23 papillary carcinomas and 11 follicular carcinomas. Positive telomerase activity was detected in 2 of 14 nodular hyperplasias (14%), 4 of 14 adenomas (29%), 12 of 23 papillary carcinomas (52%) and 10 of 11 follicular carcinomas (91%). The cancers that are negative for telomerase activity are mostly in early stage (stage I or II). These results suggest that telomerase reactivation plays a role during the development of thyroid cancer.

Endovascular embolization of arteriovenous fistulas of the external carotid artery

BACKGROUND

External carotid arteriovenous fistulas (AVFs) are rare and most hospitals have limited experience with their management. This study was designed to evaluate the effectiveness and safety of endovascular embolization of AVFs of the external carotid artery under angiographic control.

METHODS

A series of 13 patients with AVFs involving the branches of the external carotid artery, all treated with endovascular embolization, were reviewed. There were 10 males and three females ranging in age from nine to 46 years, with a mean of 27 years. The most frequent presenting symptoms were pulsatile tinnitus, followed by bruit and/or thrill, ocular problems, headache and a pulsatile mass in the neck. The middle meningeal artery was most often involved, followed by the internal maxillary artery and the occipital artery. The AVFs were caused by trauma in 10 patients and occurred spontaneously in three. N-butyl-2-cyanoacrylate was used to embolize the fistula in 11 patients and a detachable balloon was used in two.

RESULTS

All the patients were cured and no significant complications were observed. No recurrence was noted after a clinical follow-up of three months to seven years (mean, 37 months).

CONCLUSIONS

Endovascular embolization proved to be a safe and effective procedure. It should be the treatment of choice for repair of external carotid AVFs.

High resolution computed tomography of temporal bone fracture

BACKGROUND

High resolution computed tomography (HRCT) is highly efficient in demonstrating the anatomy of the temporal bone. This study evaluates its application to temporal bone fractures (TBF).

METHODS

We collected data from 26 cases of TBF in the past two years. All cases underwent HRCT examination. The clinical information was reviewed and correlated with the imaging findings.

RESULTS

Eighty-six percent of the cases had longitudinal fractures. Axial scans were the most useful in identifying the fracture line. Mastoid opacification on routine head computed tomography (CT) was also useful in indicating possible TBFs. Complications of TBF, such as ossicular chain disruption, facial nerve damage or otorhino-liquorrhea, were identified clearly using HRCT.

CONCLUSIONS

To minimize or prevent the sequelae of TBF, accurate radiologic evaluation is necessary as soon as possible after injury. HRCT of the temporal bone delineates the bony and soft tissue anatomy with high accuracy and we recommend it as the diagnostic modality of choice.

Mouse brain potassium channel beta1 subunit mRNA: cloning and distribution during development

The pore-forming alpha subunits of voltage-gated potassium channels in neurons and other excitable cells are expressed in association with accessory beta subunits. These subunits both promote insertion of channel complexes into surface membranes and influence their electrophysiological properties. As part of an effort to understand the regulation of voltage-gated potassium channels during development, we cloned the mouse homolog of the rat Kvbeta1 potassium channel subunit. Kvbeta1 subunits are known to associate preferentially with Shaker (Kv1)-related alpha subunits. We then used a digoxigenin-tagged cRNA probe and in situ hybridization techniques to visualize the appearance of Kvbeta1 mRNA transcripts during late embryonic and early neonatal development of the mouse brain. We detected Kvbeta1-specific labeling of cells in hippocampus, cerebral cortex, caudate putamen, colliculus, and cerebellum. In hippocampus, we observed Kvbeta1 mRNA in CA3 pyramidal neurons at the earliest time examined, embryonic day 16 (E16). Between E16 and postnatal day 7 (P7), cell labeling increased uniformly across the pyramidal neurons of Ammon's horn (CA1, CA2, and CA3). Subsequently, between P7 and P22, regional differences characteristic of mature hippocampus appeared-intense labeling of neurons in CA3 and CA1, and less in CA2. In cortex, labeling of cells in the subplate and cortical plate layers was observed at E16. During development, the intensity of this labeling increased, and labeled cells persisted into the adult stage in the deep cortical layer (VIb) formed from subplate neurons. Additional labeling of scattered solitary cells in cortical layers II-VIa emerged between P3 and P7 and was prominent in mature cortex. In caudate putamen, Kvbeta1-labeled cells were observed at P1 and were restricted to the lateral and rostral half of the caudate. During development, labeling expanded caudally and medially and eventually filled the mature caudate putamen. In colliculus, a small population of inferior colliculus cells showed labeling at P7, and additional labeling of scattered cells appeared during development. In superior colliculus, labeling was observed only in the adult deep gray layer. In cerebellum, intense labeling was observed in Purkinje cells at all stages between P1 and adult. Labeling was also seen in granule neurons in the external granule layer at early postnatal stages and in the inner granule layer beginning at P7.

Development, validation, and interlaboratory comparison of an HMG-CoA reductase inhibition assay for quantitation of atorvastatin in plasma matrices

An HMG-CoA reductase inhibition assay was developed and validated for quantitation of atorvastatin in human, dog, rat, and mouse plasma. Atorvastatin was isolated from plasma by protein precipitation. Rat-liver microsomes were used to provide the reductase enzyme. The method was validated by assaying calibration standards and quality controls in triplicate on each of the 3 days. A customized computer program was used for data calculation. Quantitation of the assay ranged from 0.36 to 16 ng/ml of atorvastatin in different plasma matrices. Assay precision and accuracy, based on the coefficient of variation and percent relative error, respectively, of quality controls were 10.4% to 14.5% and within +/- 6.25% in human; 4.89% to 10.6% (+/- 8.13%) in dog; 2.68% to 8.62% (+/- 5.00%) in rat; and 3.68% to 8.96% (+/- 5.38%) in mouse plasma. The method has been applied to pharmacokinetic studies of atorvastatin in human and toxicokinetic studies in dog, rat, and mouse after atorvastatin administration. Atorvastatin equivalent concentrations in a set of plasma samples from subjects receiving single and multiple doses of atorvastatin were determined by validated HMG-CoA reductase inhibition assays at four different laboratories. Results were compared using linear regression and concordance correlation statistical procedures. Good agreements among these data indicated that results from different laboratories with the same validated method can be used interchangeably.

A prospective study of bone mineral density change in Taiwan

In 1989, a cross-sectional study was carried out in Lin-Kou Township, Taiwan, to determine the distribution of bone mineral density (BMD) in the lumbar spine of Chinese people. Lumbar spine BMD was measured using dual-photon absorptiometry in 404 healthy volunteers (266 women and 138 men, aged 15 to 83 years). In 1994-1995, 318 of the same volunteers were reexamined for the present study. Except for there being fewer males and smokers present, there were no significant differences between the second survey respondents and nonrespondents. Spine BMD decreased at over 1% per year in Chinese women over age 50, which was somewhat higher than reported for caucasian women. Since there was a loss of BMD in Chinese women after their 20s, a case can be made for starting preventive activities for female adolescents. There were no differences in the mean BMD change rates among the different age groups of Chinese men. Baseline BMD, menopause, and weight change were associated with the lumbar spine BMD change rates in Chinese women. Body mass index was the only variable significantly associated with BMD change in Chinese men. The rate of BMD change was not associated with diet.

Radiologic placement of subcutaneous infusion chest ports for long-term central venous access

OBJECTIVE

The technical success and complications associated with radiologic placement of subcutaneous implantable chest ports for long-term central venous access were evaluated.

MATERIALS AND METHODS

Between May 1, 1996, and December 31, 1996, 80 chest ports were placed in 80 consecutive patients using the right internal jugular vein as the preferred access route. All procedures occurred in interventional radiology suites with patients receiving conscious sedation. Both sonography and fluoroscopy were used for venipuncture and to guide port insertion. Follow-up was obtained by the clinical service and by performing chart reviews electronically.

RESULTS

Technical success was 100%, and follow-up was obtained in all patients. One procedural complication occurred that was unrelated to actual catheter placement. Mean catheter use was 155 days (total, 12,168 days; range, 18-303 days). Confirmed catheter-related infection rate was 3%, or 0.016 per 100 access days; symptomatic catheter-related central venous thrombosis rate was 1%, or 0.008 per 100 access days; and 5% of catheters were removed prematurely. No instances of hematoma formation, catheter tip migration or malposition, symptomatic air embolism, spontaneous catheter fracture, or pneumothorax were found.

CONCLUSION

With the benefit of both sonographic and fluoroscopic guidance, subcutaneous implantable chest ports can be inserted by radiologists with equal or lower complication rates than those reported in surgical series. Image-guided insertion of chest ports should replace rather than supplement unguided placement.

Androstanediol and 5-androstenediol profiling for detecting exogenously administered dihydrotestosterone, epitestosterone, and dehydroepiandrosterone: potential use in gas chromatography isotope ratio mass spectrometry

The basis of a potential method for confirming intake of four natural androgens (testosterone, epitestosterone, dihydrotestosterone, and dehydroepiandrosterone is presented. The method relies on isolating from urine a steroid fraction containing androstenediol and androstanediol metabolites of these natural steroids and analyzing their 13C content by gas chromatography, combustion, isotope ratio mass spectrometry. The steroids were recovered from urine by conjugate hydrolysis with a Helix pomatia preparation (sulfatase and beta-glucuronidase), Girard T reagent separation to obtain a nonketonic fraction, and Sephadex LH-20 chromatography for purification. Metabolites appropriate for all of the natural steroids could be separated (as diacetates) by gas chromatography on a DB-17 capillary column viz.: 5 alpha (and beta)-androstane-3 alpha,17 alpha-diol (epitestosterone as precursor); 5 alpha (and beta)-androstane-3 alpha,17 beta-diol (testosterone as precursor); 5-androstene-3 beta,17 beta-diol (dehydroepiandrosterone precursor); and 5 alpha-androstane-3 alpha,17 beta- (and 17 alpha-) diol (dihydrotestosterone precursor). Measurement of the 13C content of the specific analytes after ingestion of the androgen precursors demonstrated a lowering of delta 13C/1000 value compared to normal values. Typically, in the male individual studied, delta 13C/1000 values for all components were -26 to -27 before drug administration and -29 to -30 at 6 h after, the latter values reflecting those obtaining for commercial synthetic steroid compared to in vivo synthesized steroid. While generally the metabolism of the steroids was as expected, this was not the case for 5 alpha-dihydrotestosterone. A major metabolite was 5 alpha-androstane-3 alpha,17 alpha-diol, which had presumably been formed by 17 beta/17 alpha isomerization, a process previously known for unnatural anabolics but not for natural hormones. The isolation, purification, and isotope ratio mass spectrometry techniques described may form the basis of a general method for confirming natural steroid misuse by sports participants.

Intracranial ganglioglioma: CT and MRI findings

Thirteen cases of pathologically proved intracranial gangliogliomas were reviewed in order to define the characteristic computed tomography (CT) and magnetic resonance image (MRI)-features. All patients were evaluated with CT and four of them were studied by MRI. Six tumors were cystic dominant mixed masses with remarkable focal contrast enhancement (6/13, 46%); and seven were solid in nature with variable contrast enhancement (7/13, 54%). Nine of them contained calcification (9/13, 69%). The temporal lobe was affected in six patients (6/13, 46%); the posterior fossa in four patients; the frontal lobe in two; the remaining huge one in the frontal, temporal and basal ganglion. On MRI, the findings were similar to those of the CT. Gangliogliomas do not have a characteristic CT and MRI features. They may appear as pure cystlike tumors, cystic dominant mixed tumors with remarkable focal contrast enhancement, solid tumors with variable contrast enhancement or diffuse involving the brain parenchyma and/or subarachnoid spaces. However, radiologists should include ganglioglioma in the differential diagnosis when we find patient has a long-standing process as well as a calcified tumor in the temporal lobe with following characteristic; cystic dominant mixed tumor with remarkable focal contrast enhancement, or a solid mass without hemorrhage or significant surrounding edema.

Electrical fixing of 1000 angle-multiplexed holograms in SBN:75

We have demonstrated electrical fixing of 1000 angle-multiplexed holograms in a 1-cm(3)volume Ce-doped SBN:75 crystal. A revealing procedure yielded an average diffraction efficiency of 0.005% for each hologram, with approximately 20% variation. The erasure resistance of the fixed gratings was verified.

Structural studies of receptor binding by cholera toxin mutants

The wide range of receptor binding affinities reported to result from mutations at residue Gly 33 of the cholera toxin B-pentamer (CTB) has been most puzzling. For instance, introduction of an aspartate at this position abolishes receptor binding, whereas substitution by arginine retains receptor affinity despite the larger side chain. We now report the structure determination and 2.3-A refinement of the CTB mutant Gly 33-->Arg complexed with the GM1 oligosaccharide, as well as the 2.2-A refinement of a Gly 33-->Asp mutant of the closely related Escherichia coli heat-labile enterotoxin B-pentamer (LTB). Two of the five receptor binding sites in the Gly 33-->Arg CTB mutant are occupied by bound GM1 oligosaccharide; two other sites are involved in a reciprocal toxin:toxin interaction; one site is unoccupied. We further report a higher resolution (2.0 A) determination and refinement of the wild-type CTB:GM1 oligosaccharide complex in which all five oligosaccharides are seen to be bound in essentially identical conformations. Saccharide conformation and binding interactions are very similar in both the CTB wild-type and Gly 33-->Arg mutant complexes. The protein conformation observed for the binding-deficient Gly 33-->Asp mutant of LTB does not differ substantially from that seen in the toxin:saccharide complexes. The critical nature of the side chain of residue 33 is apparently due to a limited range of subtle rearrangements available to both the toxin and the saccharide to accommodate receptor binding. The intermolecular interactions seen in the CTB (Gly 33-->Arg) complex with oligosaccharide suggest that the affinity of this mutant for the receptor is close to the self-affinity corresponding to the toxin:toxin binding interaction that has now been observed in crystal structures of three CTB mutants.

Pharmacokinetics of pirmenol enantiomers and pharmacodynamics of pirmenol racemate in patients with premature ventricular contractions

The pharmacokinetics and pharmacodynamics of pirmenol were investigated in 12 patients with premature ventricular contractions (PVCs) after oral administration of racemic pirmenol, 100 mg and 200 mg every 12 hours. Holter monitoring was performed and serial blood samples were collected after the seventh doses. Plasma concentrations of pirmenol enantiomer were determined using a stereospecific liquid chromatographic assay. Clearance of total (-)-pirmenol was 20% higher than that of total (+)-pirmenol, and the difference in unbound clearance was 45% between enantiomers. Total pirmenol showed a smaller difference because of stereoselective protein binding, with 25% (100-mg dose) or 27% (200-mg dose) higher fraction unbound for (+)-pirmenol than for (-)-pirmenol. Distribution volume was similar for both enantiomers. Dose-dependent clearance was observed for unbound pirmenol enantiomers, as both enantiomers showed 20% lower unbound clearance at the higher dose. Antiarrhythmic effect (% reduction in PVCs from baseline) was correlated with plasma concentrations of pirmenol using a sigmoid maximum drug effect model, and patients showed a large variability in their antiarrhythmic response to plasma concentrations of pirmenol. The median value for minimum effective plasma concentration of racemic pirmenol was 1.5 micrograms/mL.

Cloning of anti-Gal Fabs from combinatorial phage display libraries: structural analysis and comparison of Fab expression in pComb3H and pComb8 phage

Anti-Gal is the most abundant natural antibody in humans. It interacts specifically with the carbohydrate epitope Gal alpha1-3Galbeta1-4GlcNAc-R (termed the alpha-galactosyl epitope). In an attempt to characterize the Ig genes encoding anti-Gal, two combinatorial phage display libraries in phagemid pComb3H were screened for anti-Gal Fabs. For this purpose, phages were incubated with biotinylated BSA coupled with alpha-galactosyl epitopes (designated alpha-Gal-BSA). Subsequently, phages complexed with alpha-Gal-BSA were isolated by streptavidin-coupled magnetic beads. Because of the low affinity of this antibody, a characteristic shared with other anti-carbohydrate antibodies, only two clones displaying anti-Gal activity were isolated. Clone G9 contained the VH gene V3-43 and VL gene DPK15, whereas clone P19 contained the VH gene V3-15 and VL gene DPL16. Both clones contained between five and 14 mutations in their H and L chain V genes. The affinity of clone G9 was found to be higher than that of clone P19, as only the former could bind to solid-phase alpha-galactosyl epitopes in an enzyme-linked immunosorbent assay. This interaction could be increased by expressing Fabs in phagemid pComb8 grown in the presence of IPTG. Under such conditions, the IPTG-activated Lac-Z promoter induces an increased expression of Fabs that are linked to phage envelope protein VIII, resulting in multiple Fab display on the phage. The data suggest that screening combinatorial phage display libraries for anti-carbohydrate antibodies may be more effective with pComb8 phage grown in the presence of IPTG.

Confirming testosterone administration by isotope ratio mass spectrometric analysis of urinary androstanediols

A gas chromatographic combustion isotope ratio mass spectrometric (GC/C/IRMS) method was used for studying the incorporation of exogenous testosterone enanthate into excreted urinary 5 alpha- and 5 beta-androstane-3 alpha, 17 beta-diols. A multistep but straightforward work-up procedure produced a simple GC chromatogram of urinary steroid acetates composed principally of two androstanediols and pregnanediol. It is anticipated that such a method may form the basis of a doping control test for testosterone that could be used as a primary method during major sporting events or alternatively as a verification technique. Urine samples from five individuals were collected before and after administration of testosterone enanthate (250 mg). The delta 13C0/1000 value of andro-stanediols was around -26 to -28 during the baseline period and decreased to about -29 to -30 in the days following synthetic testosterone administration. One of the other major steroids in the chromatogram, pregnanediol, was utilized as the "internal standard," because its delta 13C0/1000 values did not markedly change following testosterone administration, remaining at -25 to -27. In all subjects studied, the delta 13C0/1000 values for androstanediols were reduced sufficiently over 8 days to confirm administration of synthetic testosterone. Although steroids isolated from urine of normal individuals from 12 different countries gave values between -24 and -28, this seemed not to be related to nationality or region. The most likely variable is the proportion of plants with low and high carbon 13 content in the diet. This variable is likely to be more affected by individual food preferences than broad ethnic food divisions. In this paper, we propose a ratio of delta 13C0/1000 for androstanediols to pregnanediol as a useful discriminant of testosterone misuse, a value above 1.1:1.0 being indicative of such misuse. The work-up procedure was designed for batch analysis and to use only simple techniques, rather than employ further instrumentation, such as high-performance liquid chromatography (HPLC), in purifying steroids for GC/C/IRMS.

Pharmacokinetics and pharmacodynamics of pirmenol enantiomers in coronary artery ligated dogs

The pharmacokinetics and pharmacodynamics of pirmenol enantiomers were investigated in coronary artery ligated mongrel dogs. Reduction in frequency of premature ventricular complexes (PVCs) was determined following intravenous administration of 5-mg/kg doses of racemic pirmenol (n = 5), (+)-pirmenol (n = 4), and (-)-pirmenol (n = 4), each given as a 5-min infusion. Electrocardiographic signals and blood samples were obtained serially over a 4-h period. Pirmenol enantiomer concentrations in plasma were determined by a stereospecific assay. Following the racemate dose, (-)-pirmenol had 47% lower clearance and 33% lower steady-state distribution volume than (+)-pirmenol. These differences could be mostly explained by stereoselective plasma protein binding, reflected in a 58% higher unbound fraction for (+)-pirmenol compared with (-)-pirmenol following racemate administration. Unbound pirmenol distribution volumes were nearly identical for both enantiomers, and unbound clearance was only 16% lower for (-)-pirmenol than (+)-pirmenol following administration of the racemate. Similar trends were observed for pirmenol enantiomers administered individually. Both pirmenol enantiomers were equally effective in arrhythmia suppression. The antiarrhythmic response of coronary artery ligated dogs to pirmenol was described by a sigmoid Emax model, and no statistically significant differences were observed in the pharmacodynamic parameters [i.e., EC50 (plasma concentration at 50% of maximum drug effect), S (constant that reflects the sigmoidal shape of the effect-concentration curve), and EC90 (plasma concentration at 90% of maximum drug effect)] for (+)-pirmenol, (-)-pirmenol, or pirmenol racemate.

A continuous method for measuring calpain activity

A simplified methodology for assaying the caseinolysis by calpains was developed. This methodology, including the incubation of calpain with casein and direct measurement of the absorbance at 500 nm, is based on the turbidity of the reaction mixture caused by the aggregation of hydrolysates during the reaction. Unlike the typical caseinolysis assay, this novel assay does not need to separate the substrate from hydrolysates and can be continuously monitored in visible wavelength range. The activity of calpain is expressed by the maximum reaction velocity (delta A500/min) at 25 degrees C).

Distribution of tacrine and metabolites in rat brain and plasma after single- and multiple-dose regimens. Evidence for accumulation of tacrine in brain tissue

Tacrine [1,2,3,4-tetrahydro-9-acridinamine monohydrochloride monohydrate (THA), Cognex] is a potent acetylcholinesterase inhibitor recently approved for treatment of mild-to-moderate Alzheimer's disease. The potential for THA and/or a metabolite of THA to accumulate in brain tissue was investigated by autoradiographic and metabolic profiling techniques in rats given single and multiple doses of [14C]THA. In addition, the brain-to-plasma distribution time course of orally administered 1-hydroxy-THA (1-OH-THA, 24 mg/kg), a primary rat metabolite with anticholinesterase activity, was also examined. Results from a 16 mg/kg single-dose study showed THA to cross the blood-brain barrier readily and concentrate in brain tissue, approximately 5-fold compared with plasma. The metabolite 1-OH-THA was found in much lower amounts relative to THA and when given separately at a similar dose the levels in brain tissue were comparable with plasma concentrations. After multiple-dose administration, THA concentrations in brain tissue were approximately 3-fold higher than those achieved after a single oral dose. However, concentration of 1-OH-THA metabolite increased only 50%. These data suggest a marked difference between the ability of THA and 1-OH-THA to accumulate in brain tissue and may reflect differences in lipophilicity as estimated by calculated log p values. The relevance of THA accumulation in brain tissue to delays observed in THA clinical management of Alzheimer's disease remains to be established.

Microsurgical replantation of the avulsed scalp: report of 20 cases

Our 4-year experience with 20 patients who had suffered avulsion of 75 percent or more of the scalp is reviewed. All patients underwent replantation using microsurgical technique with 100 percent survival in 16, partial survival in 3, and failure in only 1 case. The emergency management and indications for replantation are demonstrated. The roles of sufficient preoperative preparation, generous debridement of damaged vessels, interpositional vein grafts, and the shortening of operative time in contributing to this success are emphasized. We developed a new surgical procedure called simultaneous vein grafts on donor and recipient sites in an effort to use less time in the anastomosis of interpositional vein grafts. Furthermore, we anastomosed the extra artery of the scalp to the vein on the recipient head when no suitable vein could be found. Intraoperative repair of the scalp sensory nerve and no postoperative use of any vasodilator or anticoagulant are discussed.

Toxicological comparison of a muscarinic agonist given to rats by gavage or in the diet

Corneal opacities and urinary tract sepsis were previously observed by the authors in rats given muscarinic agonists mixed in the diet or by gavage. To explain the differential toxicity generated by each means of administration, toxicokinetics of the muscarinic agonist CI-979 were investigated. In addition, the muscarinic antagonist scopolamine was co-administered with CI-979 to evaluate the relationship of these effects to pharmacological mechanism of action of CI-979. Female rats were given CI-979 daily by gavage at 0, 1, 10 and 30 mg/kg body weight or in the diet at 0, 1, 10 and 50 mg/kg body weight for up to 14 days. Dose-related clinical signs of muscarinic stimulation, such as sialorrhoea and dacryorrhoea, were observed predominantly in rats given 10 and 30 mg/kg body weight CI-979 by gavage, and corresponded with the high plasma drug concentrations. In contrast, hydronephrosis, pyelonephritis, and inflammation and necrosis of the kidney, urinary bladder, urethra and urinary papilla were linked to sustained, albeit lower plasma drug concentrations attained by dietary administration of CI-979 at 10 and 50 mg/kg body weight. Comparable incidences of corneal opacities were induced by both means of administration, but lesions appeared more rapidly and were generally of greater severity when CI-979 was given in the diet. The induction of corneal lesions, as well as urinary sepsis, may not relate simply to maximum plasma concentrations or to areas under the curve per se, but rather may arise when plasma drug concentrations are sustained. Corneal opacification and development of urinary tract pathology were inhibited by scopolamine, suggesting that these effects were related to the muscarinic mechanism of action of CI-979.

Staurosporine resistance accompanies DNA tumor virus-induced immortalization and is independent of the expression and activities of ERK1, ERK2, cyclin A, cyclin-dependent kinase (cdk) 2, and cdk4

Staurosporine, a potent protein kinase inhibitor, has been shown to arrest the growth of a number of normal cell types in the G1 phase of the cell cycle, while having little effect on several transformed lines. We wished to determine whether increased resistance to staurosporine was a common feature of virus-immortalized human cells and whether this phenotype was an early event following the expression of SV40 tumor antigens. Human foreskin keratinocytes immortalized by the SV40 DNA tumor virus displayed an increased resistance to staurosporine-induced growth arrest when compared with normal parental cells, as has been seen in human diploid fibroblasts. Keratinocytes immortalized by human papillomaviruses, or by just the human papillomavirus E6 and E7 oncogenes were also staurosporine resistant, suggesting that this phenotype often accompanies the immortalization of human cells by DNA tumor viruses. Acquisition of staurosporine resistance was a late event during immortalization, because precrisis human diploid fibroblasts that expressed the SV40 large T and small t antigens were not resistant to staurosporine. The same parental cells that were fully immortalized by SV40 were resistant. Staurosporine resistance was not the result of increased activities and/or expression of cyclin A, cyclin-dependent kinase (cdk) 2, cdk4, or the mitogen-activated kinases ERK1 and ERK2. Although increased activities and/or expression of cyclin A and cdk2 and cdk4 proteins, but not ERK1 or ERK2, were associated with immortalization, similar increases were found in staurosporine-sensitive precrisis cells expressing SV40 tumor antigens.

The effect of water-soluble vitamin E on cyclosporine pharmacokinetics in healthy volunteers

We evaluated the effect of water-soluble vitamin E (d-alpha-tocopheryl polyethylene glycol 1000 succinate [TPGS]; Liqui-E) on the oral pharmacokinetics of the cyclosporine, a poorly available (approximately 30%) drug, in healthy volunteers. Ten healthy subjects were given two doses of oral cyclosporine (10mg/kg) separated by a 7-day washout period. Oral TPGS (2.6 IU/kg) was administered concomitantly with one of the cyclosporine doses in a randomized order. A significant increase was observed in area under the blood concentration-time curve (AUC;mean +/ SD) with concomitant TPGS administration (3908 +/- 2601 versus 6296 +/- 5102 ng x hr/ml). Significant decreases were observed in apparent oral clearance (0.24 +/- 0.14 versus 0.15 +/- 0.08 L/hr/kg) and apparent oral steady-state volume of distribution (1.57 +/- 0.95 versus 1.07 +/- 0.73 L/kg). No significant changes were observed in the ratios of metabolites to parent drug AUC values. The comparable relative decreases in apparent oral clearance (38%) and apparent oral steady-state volume of distribution (30%) with TPGS are most likely explained by enhanced absorption, decreased counter transport back into the intestine by P-glycoprotein, or some unknown mechanism by which cyclosporine is protected from metabolism in the gut, thereby increasing bioavailability.

Cloning, characterization, and expression of the nitric oxide-generating nitrite reductase and of the blue copper protein genes of Achromobacter cycloclastes

The nitrite reductase (NIR) and blue copper protein (BCP) genes have been cloned from Achromobacter cycloclastes and characterized. NIR gene encodes a protein of 378 amino acid residues including a putative signal peptide of 37 residues. BCP gene encodes a protein of 148 residues with a 24-residue signal peptide. The DNA-derived amino acid sequence of NIR is in complete agreement with that from Edman degradation and the DNA coding sequence of BCP is also consistent with its partial N-terminal amino acid sequence. Both genes contain their own FNR box in the 5' upstream region and a TA-rich region that could be the transcription start site. These two genes are separated by at least 10 kb. Based on these observations it is very likely that these two genes, although functionally related, are regulated independently. Both proteins could be expressed in E. coli, and both of the expressed proteins could be recognized by their respective antisera. The expressed NIR demonstrates full enzymatic activity. The similarity of both proteins to the counterparts from Alcaligenes faecalis S-6 is discussed.

A novel brain cysteine protease forms an SDS stable complex with the beta-amyloid precursor protein

Alzheimer's disease (AD) brain accumulates beta-protein (A beta) a peptide proteolytically derived from the beta-amyloid precursor protein (APP). The abnormal production and aggregation of A beta have been implicated in the pathogenesis of the disease. The mechanism of production of A beta in vivo is not yet clear; but endoproteases capable of degrading APP are likely to be involved in the process. We have isolated a protease from AD brain by following its activity in digesting a synthetic peptide of 10 amino acids derived from the APP sequence flanking the N-terminus of A beta. The protease was purified by a fractionation scheme including ammonium sulfate precipitation and column chromatography using hydrophobic interaction, anion exchange, affinity, hydroxyapatite and size exclusion gels. The purity of the final product was assessed on a silver stained SDS gel by the presence of a single band. Microsequencing was performed following trypsin digestion of the sample. Internal peptide sequences were found to have sequence homology to cysteine proteases in the database. The enzyme requires DTT for activity and can be inhibited by specific inhibitors of cysteine but not serine proteases. The purified enzyme has a pI of 5.0 and a native tetrameric structure with subunits of 48 kD each. The enzyme is capable of digesting APP and generating a short peptide recognizable by antibodies specific to the C-terminus of APP. Interestingly, the purified protease also forms heat- and SDS-stable complexes with APP.

Granular cell tumour of the neurohypophysis

Granular cell tumours of the neurohypophysis are very rare. Their aetiology and nature are uncertain. Most investigators consider them to arise from pituicytes or Schwann cells of the posterior lobe of the hypophysis. They are found most commonly in older people. A surgically proven symptomatic case is reported.

Wrist injuries in adolescent gymnasts of a Chinese opera school: radiographic survey

PURPOSE

To determine the prevalence of chronic wrist injuries among adolescent gymnasts and the consequences of repetitive stress.

MATERIALS AND METHODS

Students of a Chinese opera school underwent radiography of both wrists and answered a questionnaire. They were separated into study (n = 261) and control (n = 63) groups according to participation in or abstinence from exercise training, respectively. They were further separated into fused and unfused physis subgroups. The ulnar variance was measured on posteroanterior radiographs. Abnormalities of distal radii were investigated.

RESULTS

An increase in both mean ulnar variance and frequency of ulnar-plus variance was noted in the study subgroups. Fourteen (8.2%) of 170 wrists of the fused physis study subgroup had an exceedingly large ulnar-plus variance. Sixty-one (17.3%) of 352 wrists had abnormal morphology of the distal radii in the unfused physis study subgroup. Widening of the physis was the most common finding.

CONCLUSION

Chronic, repetitive stress in the wrists of adolescent gymnasts results in a localized growth disturbance of the distal radius with resultant ulnar-plus variance. Stress injuries of the physis may lead to permanent sequelae, even in asymptomatic individuals.

Chronically stressed wrists in adolescent gymnasts: MR imaging appearance

PURPOSE

To investigate the magnetic resonance (MR) imaging appearance of a chronically stressed wrist and to assess the utility of MR imaging for evaluation of injuries to the growth plate.

MATERIALS AND METHODS

Coronal T1-weighted spin-echo and gradient-echo MR images were obtained of 93 wrists in 47 high-risk gymnasts of a Chinese opera school. MR imaging and radiographic findings were correlated in 93 wrists.

RESULTS

The major MR imaging abnormalities of 47 radii with abnormal radiographic findings were horizontal fractures (n = 23), physeal cartilage extension to metaphysis (n = 17), and physeal widening (n = 17). The major MR abnormalities of 46 radii with normal radiographs included physeal cartilage extension (n = 12), metaphyseal bone bruise (n = 8), and vertical fractures (n = 4).

CONCLUSION

Physeal cartilage extension into the metaphysis represents a healing sign in chronically stressed adolescent wrists. MR imaging findings including horizontal fracture and physeal cartilage extension to the metaphysis suggest that physeal widening occurred secondary to metaphyseal injury.

Disposition of gabapentin (neurontin) in mice, rats, dogs, and monkeys

Gabapentin, an analog of gamma-aminobutyric acid, exhibits anticonvulsant properties in both animal models and humans. Gabapentin pharmacokinetics was studied in laboratory animals using HPLC and radiometry. Oral bioavailability was 40% in monkeys administered 25 mg/kg, 79% in mice and rats receiving 50 mg/kg, and 80% in dogs administered 50 mg/kg. Binding to plasma proteins was < 3%. Maximum blood or plasma concentrations generally occurred within 2 hr of an oral dose. In rats and monkeys, increases in maximum plasma concentrations and/or areas under the curve were less than dose-proportional following oral administration, most likely because of saturable absorption. However, intravenous pharmacokinetics in rats were linear over the dosage range of 4-500 mg/kg. Mean intravenous elimination half-life was 1.7 hr in rats, 2.9 hr (14C only) in dogs, and 3.0 hr in monkeys. In rats and dogs, repeated administration did not alter gabapentin or 14C pharmacokinetics. Additionally, gabapentin did not induce hepatic cytochrome P450 monooxygenases in rats. There were no age- (rats only) or gender-associated changes in pharmacokinetic parameters. [14C]Gabapentin was extensively distributed to tissues. In the dog, gabapentin was metabolized to N-methylgabapentin (approximately 34% of dose); whereas metabolism in mouse, rat, and monkey was minimal (< 5%). The principal route of excretion was via urine. In summary, as an antiepileptic drug, gabapentin exhibited desirable pharmacokinetic properties, such as linear elimination kinetics, not highly bound to plasma proteins, not extensively metabolized, and not an inducer of hepatic cytochrome P450.

Factors involved in nuclear reprogramming during early development in the rabbit

Mechanisms of nuclear reprogramming and assessment of potential malfunctions that could be deleterious for development were evaluated in rabbit zygotes, parthenotes, and nuclear transfer embryos by analysis of DNA replication, nucleolar fibrillarin label, and localization of nuclear material reactive to the MPM-2 antibody. Nuclear transfer embryos were derived from G1/early S-phase donor nuclei and MII oocytes. In nuclear transfer embryos, DNA rereplication was likely to have occurred because label was incorporated, possibly in the centromeric regions of the chromosomes, prior to premature chromosome condensation and again following pronuclear formation. In parthenotes, DNA replication began very late in the cell cycle, which may be due to deficiencies in the artificial activation stimulus. The presence of fibrillarin label in the nucleolus was used as an indication of nucleolar transcriptional activity. Fibrillarin label was absent in embryos of all types up to the 16-32-cell stage. Although fibrillarin reappeared in nuclear transfer and parthenote embryos at the appropriate stage, not all blastomeres showed label indicating impaired development in these embryos. Labelling of phosphorylated epitopes by MPM-2 antibody showed a change in pattern of labelling during early development. Early cleavage stage embryos did not exhibit labelling over the spindle poles as did blastomeres from 32-cell embryos and tissue culture cells. All cell types exhibited labelling during interphase as dots located primarily over the nucleus in blastomeres from 32-cell embryos and in tissue culture cells, together with cytoplasmic label in embryos at early cleavage stages. Nuclear transplant embryos had a normal pattern of MPM-2 label. In contrast, the appearance of MPM-2 label in parthenotes depended on the type of calcium stimulation. These results demonstrate defects in DNA synthesis, nucleolar activity, and specific phosphorylation events, likely resulting from an improper activation stimulus and chromosome condensation in the transplanted nucleus.

Embolization of carotid cavernous fistula by means of direct puncture through the superior orbital fissure

PURPOSE

To embolize carotid cavernous fistulas (CCFs) by means of transorbital puncture of the cavernous sinus (CS) and the cavernous segment of the internal carotid artery (ICA) through the superior orbital fissure.

MATERIALS AND METHODS

Five patients with CCF were treated with embolization of the CS, and six were treated with embolization of both the CS and the cavernous portion of the ICA after transorbital puncture. All except one had previously undergone occlusion of the ipsilateral proximal ICA before direct transorbital puncture.

RESULTS

The fistulas in these cases were all obliterated completely. Only two patients had temporary ptosis. No other remarkable complications were noted. The patent ICA on the side of the fistula in one patient remained patent after embolization.

CONCLUSION

Direct transorbital puncture through the superior orbital fissure is an alternate treatment for CCF, especially when the ipsilateral ICA has been occluded.

Inactivation of histone H1 kinase by Ca2+ in rabbit oocytes

The present study investigated the role of intracellular Ca2+ (Ca2+i) elevation on the inactivation of maturation promoting factor (MPF) in rabbit oocytes. The effects of the number of Ca2+ stimulations and of the amplitude of Ca2+i elevation on the profile of histone H1 kinase activity were determined. A Ca2+ stimulation consisted of transferring mature oocytes from culture medium to 0.3 M mannitol containing 0.1-1.0 mM CaCl2, and pulsing them at 1.25 kV/cm for 10 microseconds, or microinjecting 2-8 mM CaCl2 into the oocyte cytoplasm. The number of electrically-induced Ca2+ stimulations was varied, and amplitude of the Ca2+i rise was controlled by altering Ca2+ concentration in the pulsing medium or the injection pipette. Ca2+i concentration was determined with fura-2 dextran; oocytes were snap-frozen at indicated time points and assayed for H1 kinase activity. The activity was quantified by densitometry and expressed as a fraction of activity in nonstimulated oocytes. Electrically-mediated Ca2+i rises inactivated H1 kinase in a manner dependent on the number of Ca2+ stimulations. A single Ca2+ stimulation inactivated H1 kinase to 30-40% of its initial activity. However, H1 kinase inactivation was only transient, regardless of the amplitude of the electrically- or injection-mediated Ca2+i elevation. Increasing the number of Ca2+ stimulations helped to maintain H1 kinase activity at basal (pronuclear) levels. The results show the necessity of a threshold of Ca2+i concentration to trigger MPF inactivation, and suggest a role for the extended period of time over which Ca2+i oscillates at fertilization.

Dual inhibitory mechanism of secretin action on acid secretion in totally isolated, vascularly perfused rat stomach

BACKGROUND/AIMS

Secretin is an inhibitory hormone of gastric acid secretion. However, its inhibitory mechanism has not been well understood. Possible roles of both somatostatin and prostaglandins were investigated.

METHODS

Totally isolated rat stomachs were vascularly perfused with Krebs-Ringer buffer containing 50 mumol/L isobutyl methylxanthine at 1.4 mL.min-1. Gastric lumen was perfused with 0.15 mol/L NaCl at 1.0 min.min-1. Effect of secretin in three different doses given intra-arterially on basal acid secretion and acid secretion stimulated by pentagastrin was studied. To determine roles of somatostatin and prostaglandins in the secretin-induced inhibition, an antisomatostatin serum and indomethacin were tested, and both somatostatin and prostaglandin E2 concentrations in portal venous effluent were determined by radioimmunoassay.

RESULTS

Both basal- and pentagastrin-stimulated acid secretion were significantly inhibited by secretin. The inhibition was completely reversed by either indomethacin or antisomatostatin serum. Secretin significantly increased concentrations of both somatostatin and prostaglandin E2. Although indomethacin blocked the increase in prostaglandin E2, secretin-induced increase in prostaglandin E2 was not affected by antisomatostatin serum or was indomethacin influenced by somatostatin level. Finally, the inhibition by somatostatin of acid secretion was not affected by indomethacin.

CONCLUSIONS

The inhibition of gastric acid secretion by secretin in rats is mediated by simultaneous releases of both somatostatin and prostaglandin E2, which independently inhibit gastric acid secretion.

Intestinal schistosomiasis japonica: CT-pathologic correlation

PURPOSE

To study the pathologic basis of intestinal wall calcification caused by Schistosoma japonicum visualized with computed tomography (CT).

MATERIALS AND METHODS

Twelve patients underwent CT of the abdomen to detect what pathologic examination proved to be schistosomiasis japonica. Eight intestinal specimens from five of the patients were subjected to radiography, and the pathologic and radiographic findings were correlated.

RESULTS

CT demonstrated curvilinear or nodular calcification in the colon in 11 patients, in the appendix in two, and in the distal ileum in one. In five patients, calcifications resembling tram tracks were found in the sigmoid colon. Pathologic examination of the specimens showed calcified eggs of S japonicum deposited more extensively in the submucosa and subserosa than in the muscularis propria, which led to the tram-track appearance.

CONCLUSION

The extensive curvilinear or tram-track calcification found in the colon in patients with schistosomiasis japonica is calcification of deposited eggs.

Percutaneous transluminal angioplasty of neck vessels

BACKGROUND

Although surgical endarterectomy or bypass is regarded as the treatment-of-choice for extracranial cerebral vascular stenosis, percutaneous transluminal angioplasty (PTA) has its role as an alternative procedure for symptomatic patients refractory to medical therapy and/or for whom surgical treatment is contraindicated.

METHODS

Occlusive blood vessels were first identified by neurologic, ultrasonic and angiographic studies. Patients were premedicated with heparin and corticosteroid. From a transfemoral approach, double lumen balloon dilatation catheter was guided across the area of stenosis, and inflated two or three times to produce dilatation. Following PTA, patients received anticoagulants and corticosteroid for a period, and were followed by clinical examination, Doppler blood-flow and angiographic studies.

RESULTS

Seventeen patients undergoing 26 procedures were included in this study. The lesions involved subclavian artery in nine cases, common carotid artery in seven, internal carotid artery in five and proximal vertebral artery in five. Digital subtraction angiography (DSA) was done immediately after PTA and showed improvement of stenotic segment (residual stenosis < 30%) in 22 vessels. Restenosis occurred in two cases of subclavian artery PTA six months later. There were three complications, including TIA in two cases and hematoma at the puncture site in one case. Clinically, symptomatic improvement was obtained in 13 cases.

CONCLUSIONS

In patients with significant atherosclerotic stenosis of neck vessels, PTA is a beneficial procedure for improving blood flow to brain circulation and for alleviating symptoms.

Fluctuations of excitability in the monosynaptic reflex pathway to lumbar motoneurons in the cat

1. It is well known that the amplitude of successive monosynaptic reflexes (MSR), elicited by afferent stimuli of constant strength, fluctuate from trial to trial. Previous evidence suggests that such excitability fluctuations within the motor pool can be introduced either pre- and/or postsynaptically. Using unanesthetized decerebrate or decerebrate/spinal cats, we attempted to evaluate the relative importance of pre- and postsynaptic mechanisms to MSR variability and the potential contribution of changes in the identities of responding motoneurons to such variability. 2. Comparisons between the MSR amplitude, measured in a severed ventral root, and the probability of firing of up to three individual motoneurons in fine filaments teased from the same root, confirmed that both correlated and uncorrelated fluctuations of motoneuron excitability are involved in MSR variability. Linear regression analysis from concurrent intracellular recordings from homonymous motoneurons showed that the MSR fluctuations were correlated with the variations in membrane potential baseline, as well as with the fluctuations in the monosynaptic excitatory postsynaptic potential peak amplitude. In all 11 cases tested, the former correlation was stronger than the latter. 3. Stimulation of the caudal cutaneous sural nerve (CCS) was used to alter the postsynaptic potential background on which triceps surae (GS) MSRs were generated. The interval chosen between CCS conditioning and the GS stimulation excluded the involvement of presynaptic inhibition. When conditioned by preceding CCS stimulation, GS population MSRs generally (8/9 cases tested) increased in amplitude without much change in their overall variance. However, the individual motoneurons that contributed to the population responses did show changes in both relative excitability and in the uncorrelated component of their response variance. About half of the concurrently recorded motoneurons (6/13) showed a decrease in relative excitability after CCS conditioning, 5/13 showed an increase, and 2/13 were unchanged. Comparison of unit and population responses indicated that the identities of the motoneurons that responded at any given level of population response were quite different with and without CCS conditioning. 4. High-frequency stimulation of Ia fibers was used to alter the state of presynaptic Group Ia-afferents that produced population MSRs. Post tetanic potentiation following high-frequency stimulation did not greatly alter the variance of population MSRs or ratio of correlated and uncorrelated fluctuations in MSR responses among individual motoneurons within the responding population. However, intratetanic depression and posttetanic potentiation of population MSRs were accompanied by marked shifts in individual motoneuron excitability relative to the population response, again indicated that changes in the identities of responding motoneurons contributes to population response fluctuations.(ABSTRACT TRUNCATED AT 400 WORDS)

Controlling chaos in the brain

In a spontaneously bursting neuronal network in vitro, chaos can be demonstrated by the presence of unstable fixed-point behaviour. Chaos control techniques can increase the periodicity of such neuronal population bursting behaviour. Periodic pacing is also effective in entraining such systems, although in a qualitatively different fashion. Using a strategy of anticontrol such systems can be made less periodic. These techniques may be applicable to in vivo epileptic foci.

Dephosphorylation of sperm midpiece antigens initiates aster formation in rabbit oocytes

During fertilization in most mammals, the penetrating sperm organizes an aster of microtubules. We have investigated the mechanisms underlying this function of the sperm by a series of experiments based on microinjection of isolated sperm midpieces into unfertilized oocytes. These midpieces contain antigens recognized by the MPM-2 antibody. These antigens, which are absent from the rest of the tail fraction, correspond to three phosphorylated polypeptides of 77, 81, and 85 kDa. Dephosphorylation with alkaline phosphatase abolishes antigenicity on blots and in whole sperm. Reactivity to the antibody disappears between 1 and 3 hr after calcium stimulation of oocytes, following the decline in H1 kinase activity and coincident with aster formation. In unactivated oocytes, no aster forms and the antigen remains unchanged. MPM-2 treatment of midpieces prior to injection blocks their ability to form asters in oocytes activated by calcium stimulation. The epitope also disappears in 6-methyl-aminopurine-treated oocytes, implying that maintenance of the phosphorylated state requires kinase activity. A result that confirms this view is that sperm midpieces dephosphorylated by alkaline phosphatase can be rephosphorylated after injection into oocytes or by exposure in vitro to a Xenopus oocyte cytoplasmic fraction high in H1 kinase activity. We suggest that the microtubule nucleation activity of sperm midpieces after fertilization is triggered by the calcium-induced decrease in maturation promoting factor, which results in dephosphorylation of specific sperm centrosomal proteins.

Stochastic versus deterministic variability in simple neuronal circuits: II. Hippocampal slice

Long time series of Schaffer collateral to CA1 pyramidal cell presynaptic volleys (stratum radiatum) and population spikes (stratum pyramidale) were evoked (driven) in rat hippocampal slices. From the driven CA1 region in normal [K+] perfusate, both population spike amplitude and an input-output function consisting of population spike amplitude divided by the presynaptic volley amplitude were analyzed. Raising [K+] in the perfusion medium to 8.5 mM, slices were induced to spontaneously burst fire in CA3 and long time series of inter-burst intervals were recorded. Three tests for determinism were applied to these series: a discrete adaptation of a local flow approach, a local dispersion approach, and nonlinear prediction. Surrogate data were generated to serve as mathematical and statistical controls. All of the population spike (6/6) and input-output (6/6) time series from the normal [K+] driven circuitry were stochastic by all three methods. Although most of the time series (5/6) from the autonomously bursting high [K+] state failed to demonstrate evidence of determinism, one (1/6) of these time series did demonstrate significant determinism. This single instance of predictability could not be accounted for by the linear correlation in these data.