TNFα from classically activated macrophages accentuates epithelial to mesenchymal transition in obliterative bronchiolitis.

Bronchiolitis obliterans syndrome is characterized by fibrotic obliteration of small airways which severely impairs graft function and survival after lung transplantation. Bronchial epithelial cells from the transplanted lung can undergo epithelial to mesenchymal transition and this can be accentuated by activated macrophages. Macrophages demonstrate significant plasticity and change phenotype in response to their microenvironment. In this study we aimed to identify secretory products from macrophages that might be therapeutic targets for limiting the inflammatory accentuation of epithelial to mesenchymal transition in bronchiolitis obliterans syndrome. TNFα, IL-1ß and IL-8 are elevated in bronchoalveolar lavage from lung transplant patients prior to diagnosis of bronchiolitis obliterans syndrome. Classically activated macrophages secrete more TNFα and IL-1ß than alternatively activated macrophages and dramatically accentuate TGF-ß1-driven epithelial to mesenchymal transition in bronchial epithelial cells isolated from lung transplant patients. Blocking TNFα, but not IL-1ß, inhibits the accentuation of epithelial to mesenchymal transition. In a pilot unblinded therapeutic intervention in five patients with progressive bronchiolitis obliterans syndrome, anti-TNFα treatment improved forced expiratory volume in 1 second and 6-min walk distances in four patients. Our data identify TNFα as a potential new therapeutic target in bronchiolitis obliterans syndrome deserving of a randomized placebo controlled clinical trial.

Diagnostic correlation between the expression of the DNA repair enzyme N-methylpurine DNA glycosylase and esophageal adenocarcinoma onset: a retrospective pilot study.

EAC in its early stages, when it can potentially be cured, is rarely symptomatic and is associated with high mortality rates because in part of late-stage diagnosis. Given that DNA repair is an important contributory factor of early-stage malignancy, our study focused on the expression of the base excision repair enzyme N-methylpurine DNA glycosylase (MPG) in EAC disease onset. MPG messenger RNA (mRNA) expression levels were determined using quantitative reverse transcriptase polymerase chain reaction from a maximum of 72 patient samples. Immunohistochemistry was further utilized for the detection of MPG protein, and semiquantitative analysis performed using an H-score approach was carried out on a total of 130 archival tissue samples of different esophageal pathologies. Nuclear localized MPG protein was detected in all nonmalignant tissues derived from the enterohepatic system, with H-score values of 3.9-5.5 ± 0.4-1.0. In cancerous tissues derived from the enterohepatic system, a 9.5-fold increase in the level of MPG mRNA expression was specifically observed in the malignant regions located within the esophagus region. Further analysis revealed a 9- and 14-fold increase in MPG mRNA expression in EAC tumor, node, metastasis stages II and III, respectively, suggesting MPG expression to correlate with EAC disease progression. Immunohistochemistry analysis further showed a sevenfold significant increase in MPG protein expression in EAC tissues. Intriguingly, there was a fivefold significant decrease in nuclear localized MPG protein expression in tissues derived from Barrett's esophagus and low-grade dysplasia. Such findings highlight a complex regulatory pattern governing DNA glycosylase base excision repair initiation, as normal tissue undergoes Barrett's metaplasia and later dedifferentiates to EAC. Indeed, disease-stage-specific alterations in the expression of MPG may highlight a potential role for MPG in determining EAC onset and thus potentially be of clinical relevance for early disease detection and increased patient survival.

Pseudomonas aeruginosa accentuates epithelial-to-mesenchymal transition in the airway.

Epithelial-to-mesenchymal transition (EMT) has been implicated in the dysregulated epithelial wound repair that contributes to obliterative bronchiolitis (OB) after lung transplantation. Acquisition of Pseudomonas aeruginosa in the transplanted airway has been shown to be a risk factor for the development of OB. We investigated the potential of P. aeruginosa to drive EMT in primary bronchial epithelial cells (PBECs) isolated from lung transplant recipients. Changes in the expression of epithelial and mesenchymal markers was assessed in cells challenged with clinical isolates of P. aeruginosa or co-cultured with P. aeruginosa-activated monocytic cells (THP-1) in the presence or absence of transforming growth factor (TGF)-ß1. P. aeruginosa did not drive or accentuate TGF-ß1-driven EMT directly. Co-culturing P. aeruginosa-activated THP-1 cells with PBECs did not drive EMT. However, co-culturing P. aeruginosa-activated THP-1 cells with PBECs significantly accentuated TGF-ß1-driven EMT. P. aeruginosa, via the activation of monocytic cells, can accentuate TGF-ß1-driven EMT. These in vitro observations may help explain the in vivo clinical observation of a link between acquisition of P. aeruginosa and an increased risk of developing OB.

Raised interleukin-17 is immunolocalised to neutrophils in cystic fibrosis lung disease.

Interleukin (IL)-17 is pivotal in orchestrating the activity of neutrophils. Neutrophilic inflammation is the dominant pathology in cystic fibrosis (CF) lung disease. We investigated IL-17 protein expression in the lower airway in CF, its cellular immunolocalisation and the effects of IL-17 on CF primary bronchial epithelial cells. Immunohistochemistry was performed on explanted CF lungs and compared with the non-suppurative condition pulmonary hypertension (PH). Airway lavages and epithelial cultures were generated from explanted CF lungs. Immunoreactivity for IL-17 was significantly increased in the lower airway epithelium in CF (median 14.1%) compared with PH (2.95%, p=0.0001). The number of cells staining positive for IL-17 in the lower airway mucosa was also increased (64 cells·mm(-1) compared with 9 cells·mm(-1) basement membrane, p=0.0005) and included both neutrophils in addition to mononuclear cells. IL-17 was detectable in airway lavages from explanted CF lungs. Treatment of epithelial cultures with IL-17 increased production of IL-8, IL-6 and granulocyte macrophage colony-stimulating factor. In conclusion, immunoreactive IL-17 is raised in the lower airway of people with CF and localises to both neutrophils and mononuclear cells. IL-17 increases production of pro-neutrophilic mediators by CF epithelial cells, suggesting potential for a positive feedback element in airway inflammation.

Inflammation and epithelial to mesenchymal transition in lung transplant recipients: role in dysregulated epithelial wound repair.

Epithelial to mesenchymal transition (EMT) has been implicated in the pathogenesis of obliterative bronchiolitis (OB) after lung transplant. Although TNF-alpha accentuates TGF-beta1 driven EMT in primary human bronchial epithelial cells (PBECs), we hypothesized that other acute pro-inflammatory cytokines elevated in the airways of patients with OB may also accentuate EMT and contribute to dysregulated epithelial wound repair. PBECs from lung transplant recipients were stimulated with TGF-beta1+/-IL-1beta, IL-8, TNF-alpha or activated macrophages in co-culture and EMT assessed. The quality and rate of wound closure in a standardized model of lung epithelial injury was assessed in response to above stimuli. Co-treatment with TGF-beta1+TNF-alpha or IL-1beta significantly accentuates phenotypic and some functional features of EMT compared to TGF-beta1 alone. Co-treatment with TGF-beta1+TNF-alpha or IL-1beta accelerates epithelial wound closure however the quality of repair is highly dysregulated. Co-treatment with TGF-beta1+IL-8 has no significant effect on EMT or the speed or quality of wound healing. Activated macrophages dramatically accentuate TGF-beta1-driven EMT and cause dysregulated wound repair. Crosstalk between macrophage-derived acute inflammation in the airway and elevated TGF-beta1 may favor dysregulated airway epithelial repair and fibrosis in the lung allograft via EMT.

Epithelial to mesenchymal transition (EMT) and airway remodelling after human lung transplantation.

BACKGROUND: Aberrant epithelial repair is a key event in the airway remodelling which characterises obliterative bronchiolitis (OB) in the transplanted lung. The potential for airway epithelium from lung transplant recipients to undergo epithelial to mesenchymal cell transition (EMT) was assessed in culture and in vivo in lung allograft tissue. METHODS: Change in epithelial and mesenchymal marker expression was assessed after stimulation with transforming growth factor beta(1) (TGF-beta(1)) alone or in combination with tumour necrosis factor alpha (TNFalpha) and compared with untreated controls. The ability of cells to deposit extracellular matrix, secrete matrix metalloproteinases (MMPs) and invade collagen was investigated. Immunolocalisation of epithelial and mesenchymal markers was compared in airway tissue from stable recipients and those with OB. RESULTS: Untreated cells maintained epithelial morphology and phenotype. TGF-beta(1) reduced expression of epithelial markers, increased expression of vimentin and fibronectin, promoted collagen I and fibronectin deposition and increased MMP-9 production. Co-treatment with TNFalpha dramatically accentuated phenotypic and some functional features of EMT. Airway epithelial biopsies from recipients with OB demonstrated significantly increased staining for mesenchymal markers and significantly reduced E-cadherin staining compared with stable recipients. CONCLUSIONS: These observations demonstrate the ability of human airway epithelium to undergo EMT and suggest this phenomenon may be a potential link between inflammatory injury and TGF-beta(1)-driven airway remodelling in the development of OB.

Understanding the importance of low-molecular weight (ethylene oxide- and propylene oxide-induced) DNA adducts and mutations in risk assessment: Insights from 15 years of research and collaborative discussions.

The interpretation and significance of DNA adduct data, their causal relationship to mutations, and their role in risk assessment have been debated for many years. An extended effort to identify key questions and collect relevant data to address them was focused on the ubiquitous low MW N7-alkyl/hydroxyalkylguanine adducts. Several academic, governmental, and industrial laboratories collaborated to gather new data aimed at better understanding the role and potential impact of these adducts in quantifiable genotoxic events (gene mutations/micronucleus). This review summarizes and evaluates the status of dose-response data for DNA adducts and mutations from recent experimental work with standard mutagenic agents and ethylene oxide and propylene oxide, and the importance for risk assessment. This body of evidence demonstrates that small N7-alkyl/hydroxyalkylguanine adducts are not pro-mutagenic and, therefore, adduct formation alone is not adequate evidence to support a mutagenic mode of action. Quantitative methods for dose-response analysis and derivation of thresholds, benchmark dose (BMD), or other points-of-departure (POD) for genotoxic events are now available. Integration of such analyses of genetox data is necessary to properly assess any role for DNA adducts in risk assessment. Regulatory acceptance and application of these insights remain key challenges that only the regulatory community can address by applying the many learnings from recent research. The necessary tools, such as BMDs and PODs, and the example datasets, are now available and sufficiently mature for use by the regulatory community. Environ. Mol. Mutagen. 60: 100-121, 2019. © 2018 The Authors. Environmental and Molecular Mutagenesis published by Wiley Periodicals, Inc. on behalf of Environmental Mutagen Society.

Radiation-induced transgenerational alterations in genome stability and DNA damage.

Mutation induction in directly exposed cells is currently regarded as the main component of the genetic risk of ionizing radiation for humans. However, recent data on the transgenerational increases in mutation rates in the offspring of irradiated parents indicate that the genetic risk could be greater than predicted previously. Here, we have analysed transgenerational changes in mutation rates and DNA damage in the germline and somatic tissues of non-exposed first-generation offspring of irradiated inbred male CBA/Ca and BALB/c mice. Mutation rates at an expanded simple tandem repeat DNA locus and a protein-coding gene (hprt) were significantly elevated in both the germline (sperm) and somatic tissues of all the offspring of irradiated males. The transgenerational changes in mutation rates were attributed to the presence of a persistent subset of endogenous DNA lesions (double- and single-strand breaks), measured by the phosphorylated form of histone H2AX (gamma-H2AX) and alkaline Comet assays. Such remarkable transgenerational destabilization of the F(1) genome may have important implications for cancer aetiology and genetic risk estimates. Our data also provide important clues on the still unknown mechanisms of radiation-induced genomic instability.

Modulation of thiopurine cytotoxicity in the HL-60 cell line by physiological concentrations of hypoxanthine.

Thioguanine and mercaptopurine are clinically important agents in widespread use for the treatment of acute leukemia. In this study the effect of low, physiological concentrations of hypoxanthine on thiopurine cytotoxicity was examined in the HL-60 human acute promyelocytic leukemia cell line. Initially the effect of cell concentration on medium hypoxanthine levels was investigated. When 10(5) to 10(6) cells/ml were used, medium hypoxanthine concentrations fell to undetectable (less than 0.1 microM) levels by 24 h, due to cell utilization. However, when the cell density was reduced to 10(3) cells/ml, it was possible to maintain a medium hypoxanthine level as low as 0.5 microM for 24 h without significant hypoxanthine depletion. This allowed for the investigation of the extent to which physiological concentrations of hypoxanthine (1.0 to 10 microM) could modulate thiopurine cytotoxicity. HL-60 cells were incubated in medium containing from 1.0 to 100 microM hypoxanthine concentrations and varying levels of thioguanine or mercaptopurine for 24 h. Cells were then washed and cloned in soft agar. Physiological concentrations of hypoxanthine (1.0 to 10 microM) provided significant protection to HL-60 cells from the cytotoxic effects of both thioguanine and mercaptopurine. An increase in medium hypoxanthine level from 1.0 to 3.0 microM resulted in a 3-fold increase in the thiopurine concentration required to kill 50% of cells. There was a linear relationship between the thiopurine concentration required to reduce clonogenic survival by 50% and medium hypoxanthine level over the hypoxanthine concentrations studied. Although thioguanine was 200-fold more potent than mercaptopurine, and an analogue of guanine rather than hypoxanthine, there was a similar degree of modulation of the cytotoxicity of both agents by hypoxanthine. These results indicate that low, physiological hypoxanthine concentrations can significantly modulate thiopurine cytotoxicity and suggest that endogenous hypoxanthine pools may have an important effect on the clinical activity of thioguanine and mercaptopurine.

Cellular pharmacokinetics of mercaptopurine in human neoplastic cells and cell lines.

The accumulation, metabolism, and retention of mercaptopurine (MP) was studied in four human neoplastic cell lines (three acute leukemia lines Molt-4, CCRF-CEM, and HL-60; and one Burkitt's lymphoma line, Wilson), each of which was sensitive to MP. Two cell lines resistant to MP (WilsonR and CCRF-CEMR) were also studied. The cell lines were incubated for 3 h in 10 microM [14C]MP and then placed in drug-free media for an additional 3 h. Cell samples were obtained at regular intervals, and the intracellular MP metabolites were measured in the acid-soluble fractions by anion-exchange high-pressure liquid chromatography. MP accumulated progressively within cells during the 3-h drug exposure period and declined rapidly when the cells were placed in drug-free media. Over 80% of the intracellular MP was present in the form of three nucleotide metabolites, MP ribose monophosphate, thioxanthosine monophosphate, and thioguanosine monophosphate. MP ribose monophosphate was found in greatest amount, accounting for 59-85% of the intracellular metabolite pool. Thioxanthosine monophosphate thioguanosine monophosphate were detected in lesser amounts. Study of leukemic cells obtained from patients demonstrated a similar pattern of MP accumulation, metabolism, and retention, although the overall amounts of the various metabolites formed were less. In contrast, there was essentially no MP nucleotide metabolite formation in the two MP-resistant cell lines. A more complete understanding of the cellular pharmacokinetics of MP in human neoplastic cells is likely to lead to a more rational use of the drug in the clinical setting.

A clinical trial of chemotherapy and RAJI immunotherapy in advanced acute lymphatic leukemia.

Patients in remission with advanced acute lymphatic leukemia were randomly assigned to receive chemotherapy alone or chemotherapy plus immunotherapy with a Burkitt lymphoma tissue culture cell line (RAJI). Remission duration in both groups were identical. Complement-dependent cytotoxic antibody was seen in 5 of 8 immunized patients and 0 of 8 controls. This antibody reacted with RAJI and both allogeneic and autologous acute leukemia cells. Antibody titers began to rise after 2 months, peaked at 4 months, and then declined prior to relapse in all patients. The time course of the increase in mixed-leukocyte culture response to RAJI was similar to immunized patients. An increased in vitro response to phytohemagglutinin was seen during drug administration in all patients. Although no clinical benefit was seen in this small number of patients with the RAJI injections, these in vitro responses are encouraging and new immunization schedules will be investigated.

Diagnosis and treatment of minimal brain dysfunction in adults: a preliminary report.

Minimal brain dysfunction (MBD) has long been considered a disorder limited to childhood. A number of longitudinal and adoption studies suggest that MBD may persist into adult life where its existence is concealed by the application of a variety of diagnostic labels. In order to test the hypothesis that MBD does persist into adulthood, 15 putative MBD adults were identified on the basis of current MBD-like complaints, self-description of MBD characteristics in childhood, and a parental rating (on a standardized form) of "hyperactivity" in childhood. Eleven of the 15 subjects were given a double-blind trial of methylphenidate hydrochloride, and all 15 were given an open trial of pemoline, imipramine hydrochloride, or amitryptiline hydrochloride. Eight of the 11 showed a significant response to the double-blind trial of methylphenidate. Of the 15, eight showed a good response to stimulants or tricyclic antidepressants, two showed a moderately favorable response, and five were unresponsive to drug therapy.

Timolol and propranolol: bioavailability, plasma concentrations, and beta blockade.

Timolol, like propranolol, is a nonselective beta-adrenergic blocker, but it is much less lipid soluble and is formulated as a single enantiomer rather than a racemic mixture. We examined the effects of such differences on bioavailability, systemic clearance, and pharmacologic response. Ten healthy subjects received placebo, 0.2 mg/kg IV propranolol, 3.2 mg/kg oral propranolol, 0.025 mg/kg IV timolol, and 0.4 mg/kg oral timolol in double-blind, randomized crossover fashion. Plasma concentrations of total drug were monitored up to 8 hr, while responses to submaximal exercise were measured at 0, 2, and 6 hr. Timolol had greater bioavailability (F = 0.61 +/- 0.06(SEM) and 0.32 +/- 0.04) and lower systemic clearance (463 +/- 74 ml kg-1 hr-1 and 1040 +/- 120 ml kg-1 hr-1) than propranolol. Half-lifes were of the same order (2.7 and 2.9 hr). There was a marginal correlation between areas under the intravenous and oral plasma concentration-time curves for timolol (r = 0.66, P = 0.054), but none for propranolol (r = 0.48, P NS). There were also correlations of the response (percent reduction in heart rate) to oral and intravenous timolol at 2 hr (r = 0.72, P less than 0.05) and 6 hr (r = 0.84, P less than 0.01) hr, but none between responses to oral and intravenous propranolol. Finally, the response to oral timolol was related to the area under its plasma concentration-time curve, whereas that to propranolol was not. We conclude that the physicochemical properties of timolol lead to greater bioavailability. Pharmacologic response to an oral dose of timolol, unlike that to propranolol, can be predicted from the response to an intravenous dose and reflects its plasma concentration.

Nonresponsiveness of serum high-density lipoprotein-cholesterol to high dose ascorbic acid administration in normal men.

In a prospective, single-blind, 12-wk study, serum lipids were measured serially in nine normal male volunteers before and during oral administration of megadose ascorbic acid (1 g vitamin C/day). Study results revealed no significant effect of vitamin therapy on serum cholesterol, high-density lipoprotein-cholesterol, triglycerides, or calculated low-density lipoprotein-cholesterol. Megadose ascorbic acid therapy is not effective in elevating serum high-density lipoprotein-cholesterol in normal adult men.

Mechanical vibration in neonatal transport.

Mechanical vibration encountered in land transports was assessed objectively through measurement of vertical acceleration experienced by neonates in transit. Vibration was most predominant in the hazardous low frequency range of 3 to 18 Hz. The peak acceleration amplitudes (intermittent thrusts) ranged from 5 to 13 m/sq sec. The root mean square acceleration (averaged vibration) ranged from to 6 m/sq sec. These vibration levels are high when compared with adult vibration tolerance limits, and may jeopardize the safety of the transported infants, particularly in long-distance transports. Further research is needed to understand the possible effects of mechanical vibration in neonates and to define safe vibration thresholds in all modes of transport. Careful-evaluation of vibratory stress and its attenuation in newer designs of transport equipment may be desirable to enhance the safety of the transported infants.

Studies on the interrelationship between the syntheses of noradrenaline and metaraminol.

1. Experiments were conducted to determine the influence of the rate of noradrenaline synthesis on the conversion of alpha-methyl-m-tyrosine to metaraminol.2. Male Wistar rats, 175-200 g, were placed into four groups and treated with (1) alpha-methyl-p-tyrosine methyl ester, 250 mg/kg; (2) DL-alpha-methyl-m-tyrosine, 400 mg/kg; (3) alpha-methyl-p-tyrosine methyl ester, 250 mg/kg plus DL-alpha-methyl-m-tyrosine, 400 mg/kg; or (4) an equivalent volume of injection vehicle. All solutions were injected intraperitoneally.3. Immediately after treatment half of the rats were transferred to 4 degrees C with the remaining animals being kept at 27 degrees C.4. The rats were killed 4, 8 and 12 h after injection, the brains, hearts, spleens and adrenals removed and analysed for adrenaline, noradrenaline, metaraminol and alpha-methyl-m-tyramine.5. In virtually all cases, both during rest (27 degrees C) and sympathetic stress (4 degrees C), treatment of the rats with alpha-methyl-p-tyrosine methyl ester increased the amount of metaraminol formed from alpha-methyl-m-tyrosine. The only organ not containing increased quantities of metaraminol in the presence of alpha-methyl-p-tyrosine methyl ester was the adrenals, taken from the rats kept at 27 degrees C. Adrenals removed from the cold-exposed rats contained more metaraminol when alpha-methyl-p-tyrosine methyl ester was combined with alpha-methyl-m-tyrosine than when alpha-methyl-m-tyrosine was used alone.6. These results demonstrate that the inhibition of noradrenaline synthesis, by treatment with the tyrosine hydroxylase inhibitor alpha-methyl-p-tyrosine methyl ester, increased the conversion of alpha-methyl-m-tyrosine to metaraminol. It is concluded that inhibiting the formation of dopa allowed increased amounts of alpha-methyl-m-tyrosine to enter the biosynthetic pathway. These results support the false sympathetic transmitter concept advanced for metaraminol.

Effects of chronic metaraminol treatment on the sympathetic activity of intact and adrenal demedullated rats kept in warm or cold environments.

1. Rats were placed at 27 degrees C or 4 degrees C and given metaraminol ((10 mg/kg)/day) in their drinking water for 8 weeks. One experiment was run using adrenal demedullated rats. These animals were treated with metaraminol, as mentioned above, and kept at 4 degrees C for 4 weeks.2. Body temperature and metabolic rate were determined at selected intervals. Urine was collected on day 7 of each week and analysed for adrenaline, noradrenaline, metanephrine, normetanephrine and 3-methoxy-4-hydroxyphenylglycol (MHPG). At the end of each study the rats were killed and the tissues removed and analysed for metaraminol, adrenaline and noradrenaline.3. All animals survived the metaraminol treatment and no change in metabolic rate or body temperature was seen. Metaraminol depressed the growth rate of the rats.4. Metaraminol caused a fall in tissue noradrenaline concentrations, with only negligible quantities being found in brain, heart, lung, liver, kidney and spleen. Only the adrenals contained significant quantities of catecholamines. All tissues contained large amounts of metaraminol.5. Despite the almost complete depletion of noradrenaline from sympathetic nerves, metaraminol did not depress the excretion of noradrenaline, normetanephrine and MHPG, in fact excretion of the latter two substances was higher in the treated animals. The failure of the drug to impair the normal cold-induced increase in noradrenaline secretion explains the survival of the rats at 4 degrees C.6. Adrenal demedullation did not prevent the metaraminol-treated rats from excreting large quantities of noradrenaline, normetanephrine and MHPG in the cold. It is apparent, therefore, that in the intact rats the noradrenaline emanated from the practically depleted nerves. The increase in MHPG excretion, seen during metaraminol treatment, suggests an increased rate of noradrenaline turnover.7. In conclusion, although metaraminol uptake is accompanied by a fall in tissue noradrenaline concentrations, the presence of metaraminol does not depress noradrenaline release. These results do not support the concept that metaraminol can replace noradrenaline and function as a false transmitter.

The formation and release of metaraminol during exposure to warm or cold environments.

1. Rats were injected intraperitoneally with alpha-methyl-m-tyrosine (400 mg/kg) and placed at either 27 degrees C or 4 degrees C. The levels of alpha-methyl-m-tyramine, metaraminol and noradrenaline were determined in heart tissue after 1, 4 and 12 hr of treatment. The excretion of metaraminol, alpha-methyl-m-tyramine, noradrenaline, adrenaline and 3-methoxy-4-hydroxyphenylglycol (MHPG) was also estimated in both treated and control rats.2. Cold exposure increased both the formation and excretion of metaraminol. Hearts removed from the cold-stressed rats 4 hr after injection contained significantly more metaraminol than hearts taken from animals maintained in the warm environment. Twelve hours after treatment, no metaraminol remained in the hearts of cold-exposed rats, whereas significant quantities of the amine still remained in the hearts of rats kept at 27 degrees C. These results support the false transmitter concept advanced for metaraminol as they demonstrate that in vivo sympathetic stimulation can increase both the formation and release of metaraminol.3. Alpha-methyl-m-tyrosine produced a greater fall in cardiac noradrenaline in the rats kept at 27 degrees C. Whereas an approximate mole-for-mole replacement of metaraminol for noradrenaline existed at 27 degrees C, no such relationships existed at 4 degrees C. Twelve hours after treatment the hearts of cold-stressed rats contained no metaraminol and only 40% of control noradrenaline levels. These results do not support the necessity for a mole-for-mole replacement of noradrenaline with metaraminol to produce a catecholamine loss.4. Alpha-methyl-m-tyrosine depressed the noradrenaline excretion for at least 24 hr in the cold-stressed rats. Excretion of 3-methoxy-4-hydroxyphenylglycol was also lower in the treated rats between 0 and 12 hr in the cold but rose abruptly between 12 and 24 hr to exceed the quantity excreted by the control animals. This increase suggests an increase in noradrenaline synthesis, which may be related to the depletion of metaraminol from the body.5. The results of this paper support the postulate that metaraminol may function as a false transmitter. They do not agree with the concept that the loss of noradrenaline from tissue sites is dependent upon a mole-for-mole replacement with metaraminol.

Adolescent idiopathic scoliosis. Long-term effect of instrumentation extending to the lumbar spine.

We evaluated eighty-three patients in whom adolescent idiopathic scoliosis had been treated with a posterior spinal arthrodesis and Harrington instrumentation extending to the second, third, fourth, or fifth lumbar vertebra. All eighty-three patients completed a questionnaire, and fifty-five patients were also examined clinically and roentgenographically at a follow-up evaluation at an average of twelve years (range, ten to sixteen years). Twelve patients had a type-I curve; twenty-six, a type-II curve; sixteen, a type-III curve; and one, a type-IV curve, according to the classification of King et al. The preoperative Cobb angle of the primary curve averaged 60 degrees and ranged from 40 to 100 degrees. The curve was an average of 35 degrees (range, 15 to 65 degrees) at the most recent follow-up evaluation. Functional assessment with use of information from the questionnaire revealed an average spine score of 81 points (range, 18 to 99 points). On the basis of the score, thirty-five patients were considered to have had an excellent result; twenty, a good result; thirteen, a fair result; and fifteen, a poor result. Sixty-three (76 per cent) of the eighty-three patients had low-back pain compared with thirty (50 per cent) of sixty individuals who served as a control group. This difference was significant (p < 0.001; chi-square test). Eighteen patients (22 per cent) needed additional spinal procedures. Fourteen patients (17 per cent) did not think that the goals of the initial operation had been accomplished.(ABSTRACT TRUNCATED AT 250 WORDS)

Muscular synergism--I. On criteria for load sharing between synergistic muscles.

The use of optimization techniques to predict individual muscle forces in redundant biomechanical systems implies the formulation of a criterion for load sharing between the muscles. In part I of this paper, the characteristics and performance of several linear and non-linear criteria reported in the literature have been compared for static-isometric knee flexion. The results show that linear criteria inherently predict discrete muscle action (orderly recruitment of muscles) whereas non-linear criteria can predict synergistic action. All criteria predict that relatively more force is allocated to muscles with large moment arms. When muscle stresses (or ratios of muscle force to maximum muscle force) are used as the decision variables in the objective function, then relatively more force is allocated to muscles with large maximum possible force as well. Future formulations of the optimization should consider the differences in fiber type composition among the muscles. Such an approach is presented in part II of the paper.