Congenital myasthenic syndrome: a tale of two siblings

Congenital myasthenic syndromes are a group of rare neuromuscular junction disorders. Traditional anticholinesterase inhibitors may not help in congenital myasthenic syndromes and in some variants may actually cause deterioration of symptoms. In this report, we describe a rare case of congenital myasthenic syndrome with heterozygous mutations in CHRNE gene (c.128A > T; heterozygous; exon 11) and COLQ gene (c.1201T > A; heterozygous; exon 16), which did not show improvement on neostigmine test but responded to treatment with oral salbutamol.

COPD exacerbation rates are higher in non-smoker patients in India

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is common among non-smokers exposed to solid fuel combustion at home. Different clinical characteristics in these patients may have significant therapeutic and prognostic implications.METHODS: We used medical record review and a questionnaire among COPD patients at 15 centres across India to capture data on demographic details, different types of exposures and clinical characteristics. Chest radiography and pulmonary function testing were performed in all 1984 cases; C-reactive protein and exhaled breath nitric oxide were measured wherever available.RESULTS: There were 1388 current or ex-smokers and 596 (30.0%) non-smokers who included 259 (43.5%) male and 337 (56.5%) female patients. Sputum production was significantly more common in smokers with COPD (P < 0.05). The frequency of acute symptomatic worsening, emergency visits and hospitalisation were significantly higher (P < 0.05) in non-smokers with COPD; however, intensive care unit admissions were similar in the two groups. There was no significant difference with respect to the use of bronchodilators, inhalational steroids or home nebulisation among smoker and non-smoker patients. The mean predicted forced expiratory volume in 1 sec in smokers (43.1%) was significantly lower than in non-smokers (46.5%).CONCLUSION: Non-smoker COPD, more commonly observed in women exposed to biomass fuels, was characterised by higher rate of exacerbations and higher healthcare resource utilisation.

Patient's Decisional Control Preferences in Palliative Care: An Indian Survey

Background: The frequency of passive decisional control (patients prefers physician to make decisions) has been reported to be variable but generally larger among patients living in developing countries. Aim: This study aimed to determine the frequency of passive DCP among patients with advanced cancer in a tertiary cancer center, and identify its association with their sociodemographic and clinical characteristics. Methods: 150 patients referred to palliative care underwent assessment of decisional control preferences using validated tools including control preference scale tool, satisfaction with decision scale and understanding of illness questionnaire. Information regarding patient characteristics including age, gender, education, marital status, employment, Karnofsky Performance Scale, cancer stage and type, religion were also collected. Descriptive statistics and logistic regression analysis were performed. Results: Median age was 48 years, Karnofsky 90, and 55.3% were men. Shared, active (patient prefers to make decision by his/her own) and passive DCP were 20.7%, 26.7% and 52.7% respectively (n = 150). 51.3 were satisfied by the way the actual decisions were made. 70.7% felt that their cancer was curable. Passive DCP did not vary across regions. Multivariate analysis shows that the passive DCP was significantly associated in better KPS [expB 1.07 (1.01-1.15), P = 0.03]. Conclusion: There are significant differences in DCP with KPS. Patients report high level of satisfaction with their treatment decision, though they have poor understanding of their prognosis and understand their treatment to be of curative intent. Individualized understanding DCP and focus on illness understanding may be important for quality care and patient satisfaction outcomes.

An interobserver reliability comparison between the Orthopaedic Trauma Association's open fracture classification and the Gustilo and Anderson classification

Aims

To evaluate interobserver reliability of the Orthopaedic Trauma Association’s open fracture classification system (OTA-OFC).

Patients and Methods

Patients of any age with a first presentation of an open long bone fracture were included. Standard radiographs, wound photographs, and a short clinical description were given to eight orthopaedic surgeons, who independently evaluated the injury using both the Gustilo and Anderson (GA) and OTA-OFC classifications. The responses were compared for variability using Cohen’s kappa.

Results

The overall interobserver agreement was ĸ = 0.44 for the GA classification and ĸ = 0.49 for OTA-OFC, which reflects moderate agreement (0.41 to 0.60) for both classifications. The agreement in the five categories of OTA-OFC was: for skin, ĸ = 0.55 (moderate); for muscle, ĸ = 0.44 (moderate); for arterial injury, ĸ = 0.74 (substantial); for contamination, ĸ = 0.35 (fair); and for bone loss, ĸ = 0.41 (moderate).

Conclusion

Although the OTA-OFC, with similar interobserver agreement to GA, offers a more detailed description of open fractures, further development may be needed to make it a reliable and robust tool. Cite this article: Bone Joint J 2018;100-B:242–6.

Distribution and metabolism of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in female rats and their pups at dietary doses

2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is a mammary carcinogen in female rats and is present in a wide variety of cooked meats. We address here the excretion of PhIP and its metabolites into the breast-milk of lactating rats and the ability of chlorophyllin, a food product derivative with chemopreventive properties, to affect these levels at low PhIP doses. Lactating female F344 rats with suckling pups were orally administered 50, 500 and 1000 ng [14C]PhIP/kg body weight. The excretion of the [14C]PhIP into milk and its distribution among the mammary tissue, liver and blood of the dam, as well as among stomach contents and liver of their suckling pups was measured using accelerator mass spectrometry (AMS). PhIP, PhIP-4'-sulfate, 4'-hydroxy-PhIP, and N2-hydroxy-PhIP-N3-glucuronide were found in the milk at all doses. The chlorophyllin (500 microg/kg) co-administration with PhIP (500 ng/kg) caused increased levels of [14C]PhIP in the milk (32%) and stomach contents (35%) of the pups relative to the animals not receiving chlorophyllin at these low PhIP doses. In contrast, lower [14C]PhIP levels in the chlorophyllin treated animals were observed in the blood (47%) and mammary tissue (68%) of the dam, as well as the pup's liver tissue (37%) compared to the animals receiving only PhIP. Chlorophyllin co-administration resulted in an increased amount of N2-hydroxy-PhIP-N3-glucuronide (42%), increased PhIP (79%) and decreased levels of PhIP-4'-sulphate (77%) relative to the animals not receiving chlorophyllin. These results suggest that PhIP and PhIP metabolites are present in the breast-milk of lactating rats at human dietary PhIP exposures and that PhIP is absorbed by the newborn. Furthermore, these results suggest that other dietary components can affect the dosimetry of PhIP in breast-feeding offspring.

Possible mechanisms for PhIP-DNA adduct formation in the mammary gland of female Sprague-Dawley rats

2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), the most abundant heterocyclic amine in fried beef, is mammary gland carcinogen in rats. Using the 32P-postlabeling method, PhIP-DNA adduct levels were measured in mammary epithelial cells isolated from female Sprague-Dawley rats given 10 daily doses of PhIP (75 mg/kg, p.o.) according to a protocol previously shown to induce mammary gland cancer. At 24 h, 48 h, 1 week and 5 weeks after the last dose of PhIP, PhIP-DNA adduct levels [relative adduct labeling (RAL) x 10(7), mean +/- SD] were 10.2 +/- 0.7, 7.9 +/- 2.7, 2.2 +/- 0.6 and 0.9 +/- 0.03 respectively. When isolated rat mammary epithelial cells (from untreated rats) were incubated in vitro with N-hydroxy-PhIP (45 microM, 1 h, 37 degrees C), PhIP-DNA adducts were detected in cell DNA (RAL = approximately 97 x 10(7); however, no adducts were detected in cells incubated with PhIP (200 microM, 15 h, 37 degrees C). Incubating cells with pentachlorophenol, an inhibitor of acetyltransferase, or incubating cells at 0-4 degrees C, reduced N-hydroxy-PhIP adduct levels by 45 and 75% respectively, indicating that formation of N-hydroxy-PhIP adducts was largely due to metabolic activation. Further studies showed that rat mammary gland microsomes had little capacity to N-hydroxylate PhIP, as assayed by the mutagenic activation of PhIP in the Ames Salmonella assay. In contrast, N-hydroxy-PhIP was metabolically activated by cytosol-catalyzed PhIP-DNA adduct formation to calf thymus DNA incubated in vitro with N-hydroxy-PhIP (2 microM) in the presence of acetyl CoA. Notably, mammary cytosolic O-acetyltransferase activation of N-hydroxy-IQ or N-hydroxy-MeIQx. All three N-hydroxylamines were activated via cytosolic proline aminoacyl-tRNA synthetase and phosphorylase, although the activities of these enzymes were approximately 100-fold lower than O-acetyltransferase. No mammary cytosolic sulfotransferase activation could be detected with any of the N-hydroxylamines. Our results are consistent with the notion that PhIP-DNA adduct formation and initiation of carcinogenesis in the rat mammary gland may be associated with N-hydroxylation of PhIP outside the mammary gland, transport of the N-hydroxylamine to the mammary gland and subsequent in situ O-acetyltransferase-catalyzed activation of N-hydroxy-PhIP.

Induction of mammary tumors in female Sprague-Dawley rats by the food-derived carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine and effect of dietary fat

2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), a carcinogen found in cooked meat, was determined to be a mammary carcinogen in female Sprague-Dawley rats on a high fat diet. Forty-three-day-old female Sprague-Dawley rats received 10 doses of PhIP (75 mg/kg, p.o., days 1-5 and 8-12). Two days after the last dose of PhIP, animals were placed on a high polyunsaturated fat diet (23.5% corn oil) or a standard low fat diet (5% corn oil). After 25 weeks on the defined diet, mammary tumor incidence (average tumor mass +/- SE) was 53% (5.7 +/- 1.3 g) and 16% (2.4 +/- 0.9 g) in rats on a high fat and standard low fat diet, respectively. The histological differences in mammary gland tumors found in animals on the standard low fat diet and the high fat diet were striking. Mammary gland tumors found in PhIP-treated rats on the low fat diet were all histologically benign. The histopathological changes in these tumors included hypertrophic changes resembling the normal mammary gland, fibrocystic changes, and sclerosing adenosis. However, 80% of the mammary gland tumors found in PhIP-treated rats on a high fat diet were histologically malignant. These tumors had several malignant phenotypes including intraductal carcinoma (papillary, cribriform, and comedotype), tubular adenocarcinoma, and infiltrating duct carcinoma. The data indicate that a high fat diet in combination with a heterocyclic amine carcinogen derived from cooked meat may enhance the incidence and severity of mammary gland cancer.

Metabolic activation of heterocyclic amine food mutagens in the mammary gland of lactating Fischer 344 rats

We investigated the ability of the mammary gland to metabolically activate 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-3,8-dimethylimidazo[4,5-f]-quinoxaline (MeIQx) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). Although mammary gland microsomes had almost no capacity to metabolically activate the parent compounds, mammary gland cytosol was able to esterify the N-hydroxylamines. Acetyltransferase was the primary enzyme responsible for the phase II activation of the N-hydroxylamines. The level of acetyl CoA-stimulated binding when N-hydroxy PhIP served as the substrate was approximately 3- and 17-fold higher than when IQ and MeIQx served as substrates, respectively. N-Hydroxy-IQ and N-hydroxy PhIP can also be activated by tRNA synthetase and phosphatase, but not by sulfotransferase. However, the levels of proline- and ATP-enhanced DNA binding was approximately 30- and 60-fold lower than the acetyl CoA-enhanced DNA binding of IQ and PhIP, respectively. Differences observed in the phase II activation of the various heterocyclic amines in the mammary gland may explain why the mammary gland is a target organ for PhIP-induced carcinogenicity but not for IQ- or MeIQx-induced carcinogenicity in Fischer 344 rats.

Metabolism of the food-derived carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine by lactating Fischer 344 rats and their nursing pups

BACKGROUND

An important class of dietary mutagens and carcinogens are the heterocyclic arylamine compounds that have been identified in a variety of cooked, protein-containing foods. Among these heterocyclic amines, 2-amino-1-methyl-6-phenylimidazo[4,5-b]-pyridine (PhIP) is potentially the most important carcinogen for human cancer risk. We have recently observed that PhIP-derived radioactivity is excreted into the breast milk of lactating rats administered [3H]PhIP.

PURPOSE

To better assess the significance of breast milk as a route of exposure of the newborn to dietary heterocyclic amines, we examined the metabolites of PhIP in breast milk and in urine of nursing pups.

METHODS

Lactating Fischer 344 rats with 5-day-old pups were given a single oral dose of 10 mg/kg of [3H]PhIP. We collected milk from the dams and urine from the pups and then analyzed the samples for metabolites of PhIP, using high-pressure liquid chromatography (HPLC). PhIP-DNA adduct levels in the tissues of the pups were determined by 32P-postlabeling analysis.

RESULTS

Three radioactive peaks were observed by HPLC separation of milk samples: an unidentified early eluting peak, 4'-hydroxy-PhIP, and PhIP. Four metabolites and the parent compound were found in urine of the pups nursed by dams given radiolabeled PhIP: PhIP-4'-O-glucuronide, PhIP-4'-sulfate, 4'-hydroxy-PhIP, and N2-hydroxy-PhIP-N3-glucuronide. 4'-Hydroxy-PhIP and its conjugates contributed approximately 60% of the radioactivity found in the urine. By 32P-postlabeling analysis, PhIP-DNA adducts were detected in spleen, lung, heart, kidney, liver, and stomach of pups at mean levels ranging from 0.06 to 0.55 adducts/10(7) nucleotides.

CONCLUSIONS

The large percentage of 4-hydroxy-PhIP and its conjugates in the urine indicates that 5-day-old pups detoxify PhIP and further metabolize 4'-hydroxy-PhIP obtained from the breast milk. The presence of the glucuronide conjugate of N-hydroxy-PhIP in the urine of pups and the lack of detectable conjugate or N-hydroxylamine itself in breast milk suggest that PhIP from breast milk undergoes metabolic activation via N-hydroxylation in 5-day-old rat pups. This conclusion was further supported by the observation that hepatic S9 fractions from the pups activated PhIP to a mutagen in the Ames Salmonella mutagenicity assay and by the presence of PhIP-DNA adducts in the tissues of the pups.

IMPLICATIONS

The findings reported here may have carcinogenic and toxicologic implications for the offspring of women who breast-feed and consume a diet rich in cooked meat.

Excretion of food-derived heterocyclic amine carcinogens into breast milk of lactating rats and formation of DNA adducts in the newborn

The distribution, DNA adduction and excretion into breast milk of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) were examined in lactating female F344 rats with 5 day old pups. Six hours after a single dose (10 mg/kg, p.o.) of radiolabeled IQ, MeIQx or PhIP to lactating dams, radioactivity in the dams was highest in the liver and kidney followed, in descending order, by the mammary gland, omental fat and brain. By 24 h after carcinogen administration, all tissues of the dams showed significantly reduced levels of radioactivity except for omental fat which changed only marginally from 6 to 24 h. 32P-Postlabeling analysis showed that the level of DNA adducts in mammary gland 6 h after dosing was 2.2, 0.7 and 0.2 adducts/10(7) nucleotides for PhIP, IQ and MeIQx respectively. In contrast, in hepatic DNA, the levels of IQ-DNA adducts (5.5 adducts/10(7) nucleotides) were 11-fold higher than those of PhIP or MeIQx. The stomach contents, liver, kidney and urine of pups nursed by dams given radiolabeled IQ, MeIQx or PhIP were radioactive, indicating that these carcinogens (and/or metabolites) were excreted into breast milk and absorbed by the pups. After a 6 h suckling period, the amount of PhIP-derived radioactivity in the stomach contents of the pups was approximately 10-fold higher than that seen with IQ or MeIQx. Urine from pups from the three groups was mutagenic in the Ames assay with Salmonella TA98 in the presence of an S9 activating system. IQ-, MeIQx- and PhIP-DNA adducts, at levels in the range of 0.25-0.46 adducts per 10(8) nucleotides, were detected in the livers of pups using the 32P-postlabeling method under intensification conditions. The results from this study indicate that breast milk is a route of exposure of the newborn to heterocyclic amines. The presence of DNA adducts in the tissues of pups further suggests that this route of exposure may have a carcinogenic consequence to the newborn.

Sequential alterations in tRNA population of 2-acetylaminofluorene-induced hepatocyte nodules

In order to investigate the possible mechanisms by which cellular alterations can start an altered onco-developmental gene expression, we studied tRNA distribution profiles during the early steps of 2-acetylaminofluorene-induced hepatocarcinogenesis. The finding of progressive and sequential alterations appears to support the hypothesis of a causal connection between tRNA changes and nodular cell proliferation, possibly through the disruption of the mechanism which regulates tRNA functional adaptation.

Glutathione and enzymes related to free radical metabolism in liver of rats fed a choline-devoid low-methionine diet

Fischer F-344 male rats, fed a choline-devoid diet that leads to a highly reproducible sequence of biochemical and biological changes with an ultimate development of hepatocellular carcinoma, show elevated levels of glutathione in the liver at 3, 6 and 8 days. Several enzymes related to the metabolism of free radicals, including superoxide dismutase, catalase, glutathione peroxidase, glutathione S-transferase and DT-diaphorase show neither increased nor decreased activity as measured between 12 h and 8 days on the diet. Thus, of several known cellular components related to the possible scavenger of free radicals in the liver, only glutathione responded to the feeding of the CD diet. It is tentatively concluded that a decrease in the levels of possible scavengers for free radicals is not a major basis for the nuclear and mitochondrial lipid peroxidation seen early in rats fed a choline-devoid diet.

DNA hypomethylation in ethionine-induced rat preneoplastic hepatocyte nodules

DNA from hepatocyte nodules induced in rats with dietary DL-ethionine and from the surrounding non-nodular liver contained less 5-methyldeoxycytidine per deoxycytidine when compared with that from normal adult liver. The degree of apparent hypomethylation, 37% in nodules and 20% in the surrounding liver, decreased somewhat (29% and 16% respectively) at 2 weeks after terminating the exposure to ethionine. Nodules and surrounding liver, like normal liver, responded to partial hepatectomy with a decrease in the 5-methyldeoxycytidine level at 24 hrs and a return to the level at the time of partial hepatectomy by 38 hrs. These findings indicate the need for careful control of cell proliferation in comparing the levels of a post-replicative DNA modification, methylation, in proliferating and non-proliferating cell populations. These findings also suggest that a portion of the hypomethylation in preneoplastic nodules may be due to a bona fide decrease in the level of cytosine methylation in the parental strand of DNA. This hypomethylation could be one basis for the altered gene expression in hepatocyte nodules, possible precursors for liver cancer.

Modulation of calcium by the carcinogenic process in the liver induced by a choline-deficient diet

A diet devoid of choline and low in methionine (CD), without any added carcinogen, has been shown to induce 100% preneoplastic nodules and more than 50% cancer in the rat liver. Attempts to understand the mechanism by which a CD diet induces liver cell cancer revealed that like chemical carcinogens, a CD diet also appears to cause alterations in DNA, perhaps mediated by free radicals. Indeed, a CD diet induces nuclear lipid peroxidation prior to the changes in DNA. The CD diet induced DNA alterations coupled with continuing liver cell proliferation may account for the induction of initiated hepatocytes by the CD diet. To gain insight into the nature of free radicals generated by the CD diet, experiments were designed to determine whether agents that modulate free radical effects influence the CD diet induced changes in the liver. We investigated the effect of Ca2+ in the modulation of CD diet induced alterations in the liver. The results show that extra Ca2+ when added to the CD diet prevented some of the early changes due to choline deficiency, such as nuclear lipid peroxidation and DNA damage, but had little or no effect on the triglyceride accumulation in the liver. Also, the same CD diet with extra Ca2+, when used as a promoter after initiation by diethylnitrosamine, decreased the number and size of early putative preneoplastic foci and nodules.

Structural requirements for progesterone binding to the hepatic endoplasmic reticulum in the female rat

Microsomes isolated from the liver of the female rat specifically bind progesterone. The progesterone-microsomal complex shows highly specific characteristics. The binding is probably associated with the carbonyl groups at positions C-20 and C-3. Other steroids compete for microsomal binding sites less effectively. Competition for progesterone binding sites by other steroids in percentages: testosterone 33; testosterone propionate, 9; 17-methyltestosterone, 23.2; cortisol, 6.4; estradiol-17 beta, 1.8; 17 alpha-ethynyl estradiol, 4.7; mestranol, 1.0; norethynodrel, 4.5; ethisterone, 7.1; lynestrenol, 4.3; medroxyprogesterone, 23.3; medroxyprogesterone acetate, 15.2; 5 alpha-pregnane-3,20-dione, 47.6; 5 beta-pregnane-3,20-dione, 20.7; pregnenolone, 14.8; 6-methylpregnenolone, 1.2; 16 alpha-methylpregnenolone, 3.8%; 20 beta-hydroxy-4-pregnen-3-one, 2.8; 3 beta-hydroxy-5 alpha-pregnan-20-one, 5.2; 4-pregnene-3 beta, 20 beta-diol, 2.1; 11 alpha-hydroxyprogesterone 21.0; 16 alpha-hydroxyprogesterone, 7.9; 17-hydroxyprogesterone, 26.7; 16 alpha, 17-epoxyprogesterone, 2.7; 16 alpha-methylprogesterone, 3.8; 6-methylpregnenolone, 1.2; 16 alpha-methylpregnenolone, 3.8; promegestone, 27.0. 3 beta-Hydroxy-5 beta-pregnan-20-one, 3 alpha-hydroxy-5 beta-pregnan-20-one, 5-pregnene-3 beta,20 beta-diol, 5-pregnene-3 beta, 20 alpha-diol; 5 alpha-pregnane-3 beta, 20 beta-diol, 5 alpha-pregnane-3 beta, 20 alpha-diol, 5 beta-pregnane-3 alpha, 20 alpha-diol, 5 beta-pregnane-3 alpha, 20 alpha-diol diacetate, 5 beta-pregnane-3 alpha, 20 beta-diol, 3 alpha, 17-dihydroxy-5 beta-pregnan-20-one, 17-hydroxypregnenolone, 6-methyl-17-hydroxypregnenolone, pregnenolone-16 alpha-carbonitrile, dihydrotestosterone and cholesterol show no competition at all. The varying degree of competition by different steroids is unrelated to their lipid solubility.