Covalent Binding of Inhaled Formaldehyde to DNA in the Nasal Mucosa of Fischer 344 Rats: Analysis of Formaldehyde and DNA by High-Performance Liquid Chromatography and Provisional Pharmacokinetic Interpretation

Covalent Binding of Inhaled Formaldehyde to DNA in the NasalMucosa of Fischer 344 Rats: Analysis of Formaldehyde and DNAby High-Performance Liquid Chromatography and Provisional PharmacokineticInterpretation. CASANOVA, M., DEYO, D. F., AND HECK, H. D'A.(1989). Fundam Appl. Toxicol. 12, 397–417. Inhalationof ³HCHO and H¹⁴CHO(6 ppm, 6 hr) resulted in the formation ofDNA-protein crosslinks in the rat nasal respiratory mucosa.The DNA was extracted and was fractionated into aqueous (AQ)and interfacial (IF) portions. AQ DNA and IF DNA were enzymaticallyhydrolyzed to deoxyribonucleosides in Tris buffer and analyzedby HPLC with liquid scintillation counting (LSC). HCHO was boundexclusively to the IF DNA, indicating that the HCHO was boundas DNA-protein crosslinks. Hydrolysis of the DNA quantitativelyreleased the HCHO; no evidence was obtained for the formationof hydroxymethyl adducts. An adduct detected previously followingincubation of mammalian cells with HCHO, N⁶-hydroxymethyldeoxyadenosine(hm6dA)[Beland F. A., Fullerton, N. F., and Heflich, R. H. (1984) J.Chromartogr. 308 121–131], was shown to be produced byreaction of HCHO with deoxyadenosine (dA) in bis-Tris bufferunder conditions similar to those used for hydrolysis of theDNA. This reaction does not occur in Tris buffer. Evidence wasobtained that most or all of the hm6dA observed can be explainedby this reaction. Based on these results, an improved methodto determine the amount of H¹⁴CHO bound to DNA was developed:the DNA is hydrolyzed in Tris buffer and analyzed by HPLC, andthe released H¹⁴CHO is derivatized with dimedone and quantitatedby LSC. Rats were exposed to a wide range of H¹⁴CHO concentrations(0.3, 0.7, 2, 6, or 10 ppm; 6 hr). DNA-protein crosslinkingoccurred at all concentrations. The formation of crosslinkswas interpreted in terms of a nonlinear pharmacokinetic modelincorporating oxidation of inhaled HCHO as a defense mechanism.The slope of the fitted concentration-response curve at 10 ppmis 7.3-fold greater than at 0.3 ppm, and the fitted detoxicationpathway is half-saturated at an airborne concentration of 2.6ppm.     

Modification of the Phe3 aromatic moiety in delta receptor-selective dermorphin/deltorphin-related tetrapeptides Effects on opioid receptor binding

The previously described cyclic delta opioid receptor-selective tetrapeptide H-Tyr-d -Cys-Phe-d -Pen-OH (JOM-13) was modified at residue 3 by incorporation of both natural and unnatural amino acids with varying steric, electronic, and lipophilic properties. Effects on mu and delta opioid receptor binding affinities were evaluated by testing the compounds for displacement of radiolabeled receptor-selective ligands in a guinea pig brain receptor binding assay. Results obtained with the bulky aromatic 1-Nal³ and 2-Nal³ substitutions suggest that the shape of the receptor subsite with which the side chain of the internal aromatic residue interacts differs for delta and mu receptors. This subsite of either receptor can accommodate the transverse steric bulk of the 1-Nal³ side chain but only the delta receptor can readily accept the more elongated 2-Nal³ side chain. Several analogs with pi-excessive heteroaromatic side chains in residue 3 were examined. In general, these analogs display diminished binding to mu and delta receptors, consistent with previous findings for analogs with residue 3 substitutions of modified electronic character. Several analogs with alkyl side chains in residue 3 were also examined. While delta receptor binding affinity is severely diminished with Val³, Ile³, and Leu³ substitutions, Cha³ substitution is very well tolerated, indicating that, contrary to the widely held belief, an aromatic side chain in this portion of the ligand is not required for delta receptor binding. Where possible, comparison of results in this delta-selective tetrapeptide series with those reported for analogous modification in the cyclic delta-selective pentapeptide [d -Pen², d -Pen⁵]enkephalin (DPDPE) and linear pentapeptide enkephalins reveals similar trends.     

NOTES ON AN ENDEMIC CENTRE OF KALA-AZAR IN THE PROVINCE OF HUPEH, CENTRAL CHINA

While the larger and more important endemic areas of kala-azar are fairly well defined, the actual extent of these areas westwards''and southwards appears to be extremely vague. In a recent article Hoeppli* states "that although kala-azar may exist in West, Central and South China, the important endemic centres so far have all been ~ound north of the Yangtze Valley." The uncertainty of our knowledge of the ex- tent,rbf the fringes of the endemic areas should constitute a challenge to all working in those places to make a determined effort to prove the presence or, if possible, the absence of the disease. In these notes I propose to record experiences gained dunng 1936-37 in the small city of Anlu (old name: Teian-fu) in Hupeh which indicate that in that district the disease occurs with sufficient frequency to constitute an endemic focus of kala-azar in Central China and only a few miles north of the Yangtze Valley. .     

Breastfeedilzg Support Services in the Neonutd Intensive-Care Unit

Objective: To describe a model for providing breastfeeding support in the neonatal intensive-care unit (NICU).
Design: Naturalistic, participant observation.
Setting: Suburban Level III NICU.
Patients: One hundred thirty-two mother-infant pairs over 1 year. Infants were hospitalized In the NICU, and mothers had initiated lactation efforts.
Interventions: Investigators provided breastfeeding interventions for the mother-infant pairs, based on identified problems, the research literature, or both.
Main Outcome Measures: Percentage of mothers who were breastfeeding at the time of discharge from the NICU.
Results: Interventions were classified into jive categories: expression and collection of mothers' milk, gavage feeding of expressed mothers' milk, in-hospital breastfeeding sessions, postdischarge breastfeeding management, and additional consultation.
Conclusions: This model was effective In preventing breastfeeding failure for this population. The model can provide the basis for NICU breastfeeding standards of care, protocols, and chart records, or for reimbursement purposes. The model also provides a framework for studying a specific category or breastfeeding intervention.     

A computerized analysis of intrinsic forces in the skin

The skin of the volar forearm is a site selected for many biometrological studies. We studied the influence of forearm position when evaluating the surface topography and mechanical properties of the skin in normal young adults. Optical profilometry of skin replicas and the suction biomechanical method (Cutometer ®, 2 and 8 mm probes) were used in combination with evaluation of the thickness and sliding mobility of the dermis and dermohypodermal tissues. The dermal and dermohypodermal thicknesses did not correlate with the various profilometric and biomechanical measurements. The surface topography and the axial sliding mobility of the skin were markedly influenced by forearm position, while the only mechanical property of the skin to be affected was skin stretchability assessed with the 2 mm probe. It is concluded that limb position mostly influences biometrological measurements made in the plane of the skin surface, while it has little effect on most of the Cutometer measurements.     

Cross system agreement for substance use disorders: DSM-III-R, DSM-IV and ICD-10

This report presents results of a field trial of Substance Use Disorders as defined by DSM-III-R, DSM-IV (proposed) and ICD-10. Diagnoses based on the three systems were derived from interviews using the Composite International Diagnostic Interview (CIDI) in a heterogeneous sample of 521 adults drawn from clinical and community settings. Two issues are addressed: (1) cross system agreement; and (2) syndrome coherence of proposed criterion sets for Substance Dependence in each of the three systems. Findings were as follows: (1) Cross system agreement for Dependence was generally high, especially between DSM-III-R and DSM-IV. (2) Cross system agreement was lower for DSM-III-R and DSM-IV Abuse and very low for DSM-IV Abuse and ICD-10 Harmful Use. (3) Agreement varied across drug categories with lowest DSM-III-R/DSM-IV agreement for alcohol abuse and DSM-IV/ICD-10 agreement for marijuana use disorders. (4) Overall prevalence differed for the three systems with DSM-IV yielding highest rates followed by DSM-III-R and ICD-10 in that order. (5) Factor analysis of Dependence criteria showed high loadings of all items on a single factor across the three diagnostic systems and for all categories of drugs. Implications for validity of the dependence syndrome construct and for revisions in DSM-IV are discussed.     

Subchronic and Chronic Inhalation Toxicity of Antimony Trioxide in the Rat

Fischer 344 rats were exposed by inhalation to Sb₂O₃ (antimonytrioxide) dust at exposure levels of 0, 0.25, 1.08, 4.92, and23.46 mg/m³ for 6 hr/day, 5 days/week for 13 weeks followedby a 27-week observation period. Subsequently, an inhalationon-cogenicity study was conducted at exposure levels of 0, 0.06,0.51, and 4.50 mg/m³ for 12 months followed by a 12-month observationperiod. The Sb₂O₃ in the subchronic study had a mass medianaerodynamic diameter (MMAD) of 3.05 ± 0.21 microns (mean± SD) with a geometric standard deviation (GSD) of 1.57± 0.06. In the chronic study, the MMAD was 3.76 ±0.84 and the GSD was 1.79 ± 0.32. Except for the eyes,no adverse clinical observations were attributed to Sb₂O₃ ineither study. In the subchronic study, corneal irregularitieswere seen after about 2 weeks of exposure and did not abateduring the observation period. In the chronic study, ophthalmoscopicevaluation at 24 months revealed a dose-related increase incataracts of 11, 24, 28, and 32% (both sexes combined) for eachgroup, respectively. Body weights were significantly lower (6%)than the control group's weights in the 23.46 mg/m³ males inthe subchronic study. These rats did not recover this weightduring the 27-week observation period. Body weights of the femalesin both studies and males in the chronic study were unaffected.There were no Sb₂O₃ effects on clinical chemistry or he-matologyin either study. Mean absolute and relative lung weights weresignificantly increased in the 4.92 and 23.46 mg/m³ groups inthe subchronic study. The 23.46 mg/m³ group's lung weights didnot recover to control levels during the 27-week observationperiod. Lung weights for rats in the chronic study were unaffected.Microscopic changes in the lungs in the subchronic and chronicstudy were limited to subacute-chronic interstitial inflammation,increased numbers of alveolar-in-traalveolar macrophages, foreignmaterial in the alveolar-in-traalveolar macrophages in the peribronchialand perivascular (chronic study only) lymphoid aggregates andin the peribronchial lymph nodes, granulomatous inflammation/granulomas,and fibrosis. In the chronic study, any observed neoplasms occurredwith comparable incidence among all groups and were within thehistorical range for controls. Clearance of Sb₂O₃ from the lungwas burden dependent and was reduced by 80/ in the 4.50 mg/m³group in the chronic study. The previously reported studies,which found Sb₂O₃ to be a carcinogen, were run at higher lungburdens. Under the exposure conditions of the current study,Sb₂O₃ was not a carcinogen.     

Subchronic Inhalation Toxicity Studies with Hydrochlorofluorocarbon 123 (HCFC 123)

Hydrochlorofluorocarbon 123 (HCFC 123) is one of the chemicalsbeing considered as a replacement for the chlorofluorocarbons.Four subchronic inhalation toxicity studies from 1 to 3 monthsin duration have been conducted with HCFC 123. One study utilizedrats and dogs, while the others were limited to rats only. Theexposure levels have ranged from 300 ppm up to 20,000 ppm. Althoughthe studies were conducted over a 14-year period, the resultswere consistent. In all studies, increases in liver weightswere seen at 1000 ppm and above; additionally, one showed thiseffect at 500 ppm. Histopathological findings were minimal,consisting primarily of focal necrosis in the liver of the dogsat 10,000 ppm. Induction of peroxisomal activity, lowering ofserum cholesterol and triglyceride levels, and an increase inurinary fluoride levels were also seen. The 4-hr LC₅₀ in therat has been reported as 35,000 ppm. At 20,000 ppm for 6 hr,the total daily dose on a concentration times time basis isalmost equal to the LC₅₀ yet, in the 4-week study, with 20 exposuresat this level, there was no mortality or even marked signs oftoxicity. There appeared to be no evidence for cumulative toxicityfrom multiple exposures in these studies. Overall, HCFC 123appears to have a low level of toxicity by the inhalation route.     

Covalent Binding of Inhaled Formaldehyde to DNA in the Respiratory Tract of Rhesus Monkeys: Pharmacokinetics, Rat-to-Monkey Interspecies Scaling, and Extrapolation to Man

Covalent Bindingoflnhaled Formaldehyde to DNA in the RespiratoryTractofRhesus Monkeys: Pharmacokinetics, Rat-to-Monkey InterspeciesScaling, and Extrapolation to Man. CASANOVA, M., MORGAN, K.T., STEINHAGEN, W. H., EVERITT, J. I., POPP, J. A., AND HECK,H. D'A. (1991). Fundam. Appl Toxicol 17, 409–428. DNA-proteincross-links were formed in the respiratory tract of rhesus monkeysexposed to [¹⁴C]formaldehyde (0.7, 2, or 6 ppm; 6 hr). Concentrationsof cross-links (pmol/mg DNA) were highest in the mucosa of themiddle turbmates; lower concentrations were produced in theanterior lateral wall/septum and nasopharynx. Very low concentrationswere found in the larynx/trachea/carina and in the proximalportions of the major bronchi of some monkeys exposed to 6 ppmbut not to 0.7 ppm. No cross-links were detected in the maxillarysinuses or lung parenchyma. The pharrnacokinetics of cross-linkformation in the nose were interpreted using a model in whichthe rate of formation is proportional to the tissue concentrationof formaldehyde. The model includes both saturable and nonsaturableelimination pathways and describes regional differences in DNAbinding as having an anatomical rather than a biochemical basis.Using this model, the concentration of cross-links formed incorrespondmg tissues of different spacies can be predicted byscaling the pharmacokinetic parameter that depends on minutevolume () and quantity of nasal mucosal DNA (M_DNA). The concentration-response curve for the average rateof cross-link formation in the turbinates lateral wall, andseptum of rhesus monkeys was predicted from that of F-344 ratsexposed under similar conditions. There was significant overlapbetween predicted and fitted curves, implying that V and M_DNAare major determinants of the rate of cross-link formation inthe nasal mucosa of different species. Concentrations of cross-linksthat may be produced in the nasal mucosa of adult men were predictedbased on experimental data in rats and monkeys. The resultssuggest that formaldehyde would generate lower concentrationsof cross-links in the nasal mucosa of humans than of monkeys,and much lower concentrations in humans than in rats. The rateof formation of DNA-protein cross-links can be regarded as asurrogate for the delivered concentration of formaldehyde. Useof this surrogate should decrease the uncertainty of human cancerrisk estimates derived by interspecies extrapolation by providinga more realistic measure of the delivered concenmtion at criticaltarget sites.     

Fat gram target to achieve high energy intake in cystic fibrosis

Higher fat and energy intakes confer a survival advantage in cystic fibrosis (CF). There is a need to develop effective nutrition programmes that ensure optimal energy intake in CF.

Methodology:

A cross-sectional measurement of clinical characteristics and energy and fat intakes in patients attending the CF outpatients clinic of the John Hunter Hospital, Newcastle was undertaken. Twenty-nine subjects, mean age 12 years (range 4.3–20.2), completed weighed food records to determine the contribution of fat to the percentage of the recommended energy intake obtained and to document use of pancreatic enzyme replacement therapy.

Results:

Diets with a high percentage of energy derived from fat did not guarantee that individuals with CF met their energy requirements. Subjects with total fat intakes of 100 g per day or greater, however, achieved in excess of 110% recommended daily intake (RDI) for energy. Up to 47% of subjects consumed more pancreatic enzyme replacement capsules than shown to give maximum effectiveness.

Conclusion:

Setting a 100 g daily fat target is a realistic way of ensuring high energy intakes in CF. Fat ready reckoners would identify the fat content of food and prescribe specific numbers of pancreatic enzyme replacement capsules to be consumed with each meal or food item.