BAC and PAC DNA for the generation of transgenic animals.
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Animals↗
Biomedical subjects
E A Gonzalez
Publications and source records attributed to E A Gonzalez.
Neuropsychological evaluation of higher functioning homeless persons: a comparison of an abbreviated test battery to the mini-mental state exam.
This study examined neuropsychological functioning in a heterogeneous population of persons who were homeless (N = 60) and compared the value of the Abbreviated Halstead-Reitan Test Battery with the Mini-Mental State Exam (MMSE). A high incidence of neuropsychological dysfunction was evident with 80% of patients showing impaired test battery performance and 35% showing an impaired MMSE. Performance on the Trail Making Test, Part B was especially impaired. Patients impaired on Trails B more often showed impaired test battery performance, suggesting it may be a better screening tool than the MMSE. Neuropsychological performance was not significantly affected by the patients' gender, age, diagnosis, or past psychiatric and medical history. Regression analysis suggested that 29% of the variance in test battery performance was accounted for by the patients' education. Results support previous findings that large numbers of people who are homeless are neuropsychologically impaired; this should be considered when planning treatment and rehabilitation.
Adult↗
Genes coding for enterotoxins and verotoxins in porcine Escherichia coli strains belonging to different O:K:H serotypes: relationship with toxic phenotypes.
Seventy-four E. coli strains isolated from piglets with diarrhea or edema disease in Spain were serotyped and examined for production of heat-labile (LT) and heat-stable (ST) enterotoxins (LT-I, LT-II, STaH, STaP, and STb) and verotoxins (VT1, VT2, and VT2v = VTe) by phenotypic (Vero cell assay and infant mouse test) and genotypic (colony hybridization and PCR) methods. In general, an excellent correlation was found between the results obtained with a PCR approach and those determined with biological assays. DNA probes used in the hybridization also showed a very good agreement with phenotypic results, with the exception of a VT1 probe that initially produced 10 false-positive reactions. The gene coding for STb (58 strains) was the most prevalent gene detected by PCR, followed by those coding for STa (46 strains), LT (19 strains), VT2v (11 strains), and VT1 (1 strain). Apparently, in Spain three seropathotypes are predominant: (i) O149:K91:H10 K88+ LT-I+ STb+, (ii) O141:K85ab:H- P987+ STaP+, and (iii) O138:K81:H14 or H- STaP+ VT2v+. We conclude that PCR is a fast, specific, and practical method for the identification of enterotoxin and VT genes in clinical and epidemiological studies.
Animals↗
Prevalence and characteristics of human and bovine verotoxigenic Escherichia coli strains isolated in Galicia (north-western Spain).
An epidemiological study was carried out to determine the incidence and the serotypes of verotoxigenic Escherichia coli (VTEC) that cause infections in Galicia (north-western Spain). Although, VTEC strains were isolated from 55 (14%) of the 387 calves sampled and the majority of bovine VTEC strains belonged to serotypes (026:H11 or H-, 091:H21, O103:H2, 0105:H18, O111:H-O113:H21, O126:H-, O128:H- and O157:H7 or H-) previously associated with human haemorrhagic colitis (HC) and haemolytic uraemic syndrome (HUS) in other countries, VTEC are not a common cause of human infections in Spain. Thus, VTEC (O26:H11 and O86:H10) were isolated from only 3 (0.6%) of the 482 children with diarrhoea investigated. We examined the 69 (3 humans and 66 bovines) VTEC strains that were initially isolated as E. coli producing a toxin cytotoxic to Vero and HeLa cells by polymerase chain reaction (PCR) using specific primers for VT1, VT2 and eae genes. PCR showed that 38 (55%) of VTEC strains carried VT1 genes. 18 (26%) possessed VT2 genes, and 10 (14%) carried both VT1 and VT2 genes. Three (one human and two bovine) strains which were formerly VTEC had lost the ability to produce verotoxins upon subculture and became negative for VT1 and VT2 by PCR. In total 35 (51%) of 69 VTEC strains, including the two human VT1+ strains of serotype O26:H11, were positive for eae sequences when tested by PCR. Presence of the eae gene was significantly more frequent (100%; 21/21) among VTEC strains with serotypes (O26:H11, O111:H-, O157:H-and O157:H7) considered as enterohaemorrhagic E. coli (EHEC) than among VTEC strains with non-EHEC serotypes (29%; 14/48) (p < 0.001). Results obtained in this study indicate that cattle may be an important source of VTEC involved in human disease. However, severe clinical syndromes caused by VTEC, such as HC and HUS, are uncommon in Spain, in comparison with North America and the UK. In any case, VTEC disease can appear on the scene very suddenly, as occurred in the UK and North America in the 1980s.
Animals↗
Prevalence and characteristics of Escherichia coli serotype O157:H7 and other verotoxin-producing E. coli in healthy cattle.
From February to July of 1994, 328 faecal samples from 32 herds were collected and verotoxin-producing Escherichia coli (VTEC) found on 84% of the farms. The proportion of animals infected varied from 0-63%. VTEC were recovered from 52 (20%) of 257 cows and from 16 (23%) of 71 calves. Although the VTEC belonged to 25 different serogroups, 7 (O8, O20, O22, O77, O113, O126 and O162) accounted for 46% of strains. Nearly 45% of the strains. Nearly 45% of the 83 bovine VTEC strains belonged to serogroups associated with haemorrhagic colitis and haemolytic uraemic syndrome in humans. However, only 2 (2%) of 83 VTEC strains isolated from cattle belonged to enterohaemorrhagic E. coli (EHEC) serotypes (O26:H11 and O157:H7), and only 8 (10%) were positive for the attaching and effacing E. coli (eae) gene sequence. Polymerase chain reaction (PCR) showed that 17 (20%) of VTEC strains carried VT1 genes, 43 (52%) possessed VT2 genes, and 23 (28%) carried both VT1 and VT2 genes. Characterization of VTEC isolates revelated a heterogeneous population in terms of serogroup and toxin type in the positive herds. This study confirms that healthy cattle are a reservoir of VTEC, but, the absence of eae genes in most bovine VTEC strains suggests that they may be less virulent for humans than eae-positive EHEC.
Animals↗
Toxigenic Escherichia coli in Spanish piggeries from 1986 to 1991.
Four-hundred and fourteen faecal samples from pigs with diarrhoea, oedema disease or healthy pigs, were collected from 65 piggeries located in different areas of Spain from 1986 to 1991. A total of 1334 Escherichia coli cultures were isolated from the pigs and studied for production of heat-labile (LT) and heat-stable (STa) enterotoxins, verotoxin (VT) and for type 1 (CNF1) and type 2 (CNF2) cytotoxic necrotizing factors. Strains producing enterotoxins (P < 0.001) or verotoxin (P < 0.05) were associated with enteric diseases of pigs. In the majority (82.3%) of piglets with strains, producing verotoxin the strains were also positive for production of STa enterotoxin. The most frequent toxin detected was STa. Although we isolated strains producing CNF1 from 1.5% of sick pigs, they were not statistically associated (P < 0.7) with enteric disease. Pigs may constitute a natural reservoir of CNF1 producing E. coli strains in Spain; their presence in the porcine intestine may be of significance in public health because such strains have been associated with human extraintestinal infections.
Animals↗
Renal osteodystrophy: pathogenesis and management.
Several biochemical and hormonal abnormalities associated with renal insufficiency lead to complex disorders of bone which are described by the term renal osteodystrophy. Assessment of renal osteodystrophy in its early stages is primarily biochemical since symptoms generally do not occur until osteodystrophy is advanced. Therapy should be initiated early in the course of renal insufficiency in order to prevent the development of severe skeletal abnormalities. Foremost among the multiple factors involved in the pathogenesis of hyperparathyroidism are retention of phosphorus and low levels of calcitriol. The principal therapies for the prevention and treatment of hyperparathyroidism include the use of calcium salts taken with meals, as phosphorus binders, to prevent the absorption of phosphorus from the intestine, correction of acidosis and careful use of vitamin D metabolites such as calcitriol or 1-alpha-hydroxycholecalciferol. The prevalence of aluminum induced osteomalacia appears to be declining as aluminum salts have been replaced by calcium containing phosphate binders and there is increased attention to adequate water purification for dialysis. Other disorders such as adynamic bone and the accumulation of beta 2-microglobulin may require bone biopsy for accurate diagnosis and are more difficult to treat effectively.
Animals↗
Scleroderma renal crisis with minimal skin involvement and no serologic evidence of systemic sclerosis.
We describe a 75-year-old male patient who developed end-stage renal failure secondary to scleroderma renal crisis. The patient had cutaneous involvement limited to his fingers and feet, and had repeatedly negative serologic tests for antinuclear antibodies. This case illustrates that scleroderma renal crisis should be considered in the differential diagnosis of unexplained acute renal failure in patients with suspected systemic sclerosis, even if they lack the typical extensive cutaneous changes and the expected serologic findings.
Aged↗
Effect of U-73,122, an inhibitor of phospholipase C, on actions of parathyroid hormone in opossum kidney cells.
The relative roles of the adenylate cyclase-protein kinase A system (AC-PKA), the phospholipase C-protein kinase C system (PLC-PKC), and increases in cytosolic calcium in mediating the final actions of parathyroid hormone (PTH) remain ill defined. Although an important role for the PLC-PKC system in the regulation of phosphate transport in response to PTH has been suggested, previous studies from our laboratory and others, in OK cells, have emphasized the major role of AC-PKA. The present studies were designed to dissociate the second messengers for PTH by using an inhibitor of PLC (U-73,122). Studies were performed in confluent cultures of OK cells with and without preincubation with U-73,122 (1 microM). This inhibitor did not alter adenosine 3',5'-cyclic monophosphate (cAMP) production or the activation of PKA in response to PTH. Preincubation with U-73,122, however, totally abolished PTH-stimulated increases in diglyceride mass, consistent with inhibition of PLC. Activation of particulate PKC was then examined in response to PTH in the absence and presence of U-73,122. Although PTH resulted in an increase in particulate PKC activity in control cultures, this effect was abolished in the presence of U-73,122 and actually decreased significantly. Therefore, having documented marked attenuation of PLC-PKC, we next examined the effects of PTH on phosphate transport. Basal phosphate uptake was not altered by 1 microM U-73,122. Dose-response curves of the inhibition of phosphate transport in response to PTH were identical in the presence or absence of U-73,122. Thus inhibition of PLC and PKC activities did not alter the effects of PTH on phosphate transport.(ABSTRACT TRUNCATED AT 250 WORDS)
1-Methyl-3-isobutylxanthine↗
Parathyroid hormone increases the expression of receptors for epidermal growth factor in UMR 106-01 cells.
PTH administration in vivo increases osteoblast number and activity, resulting in increased bone formation, and also increases osteoclast-mediated bone resorption. Studies in vitro, however, have shown that the actions of PTH on osteoblast-like cells are inhibitory and catabolic, as shown by decreases in growth rate and collagen synthesis and increases in collagenase production. The present studies were designed to investigate possible mechanisms for these observations by examining the effects of PTH on the response of osteoblast-like cells to the osteoblast growth factor, epidermal growth factor (EGF). Confluent cultures of UMR 106-01 cells were treated with rat PTH-(1-34) for periods up to 72 h, and EGF receptors were measured with [125I]EGF. PTH, in a dose- and time-dependent manner, increased the number of EGF receptors 2-fold. The half-maximal effect of PTH occurred at a concentration of 1 nM, the same PTH concentration that resulted in half-maximal increases in cAMP generation. The increase in EGF binding was associated with an enhanced biological effect, as shown by augmentation of EGF-stimulated diglyceride production. The effect of PTH could be reproduced by the addition of 8-bromo-cAMP, but not by the phorbol ester phorbol myristate acetate. In the presence of cyclohexamide, the effect of PTH on EGF binding was abolished, suggesting that new protein synthesis was required to increase the number of EGF receptors. Northern blots of total RNA, using a cDNA probe encoding the extracellular domain of the rat EGF receptor, revealed that PTH treatment resulted in a 2- to 3-fold increase in the level of EGF receptor mRNA. These data suggest that the proliferative effects of PTH on the osteoblast may be mediated indirectly by a PTH-induced increase in the number of EGF receptors.
Animals↗
Serotypes and colonization factors of enterotoxigenic Escherichia coli isolated in various countries.
One hundred and six enterotoxigenic E. coli (ETEC) isolated from many geographical areas were serotyped and investigated for the presence of colonization factor antigens CFA/I and CFA/II, the expression of mannose-resistant haemagglutination (MRHA) and the levels of surface hydrophobicity. CFA/I was found in 6 (17%) of 36 LT+STa+ strains and in 15 (54%) of 28 STa+ strains; CFA/II was found in 16 (44%) of 36 LT+STa+ strains. None of 42 LT+ strains showed CFA/I or CFA/II. CFA/I was found in ETEC of serotypes O63:K-:H-, O78:K80, O128:K67 and O153:K:H45, whereas CFA/II was found in serotypes O6:H-, O6:K15:H16 and O6:K?:H40. Of the 69 CFA/I- CFA/II- ETEC strains, 9 (13%) showed MRHA with some of the seven erythrocyte species used and 21 (30%) were hydrophobic. Among the 21 hydrophobic strains CFA-negative we have detected: (i) 6 LT+ strains of serogroup O25 negative for MRHA, (ii) 5 strains O159 (4 LT+ and 1 LT+ STa+) also negative for MRHA, and (iii) 3 STa+ strains of serotype O27:K-:H7 that haemagglutinated calf and sheep erythrocytes when grown on Minca-Is. The 106 ETEC strains belonged to 20 different O serogroups. However, 77 (73%) were of one of nine serogroups (O6, O8, O25, O27, O78, O148, O153, O159 and O167). E. coli strains belonging to O6 and O153 groups predominated among ETEC isolated in Spain, O159 strains in the Central African Republic, O25 and O148 strains in Japan, and O15 and O78 strains in India.
Adult↗
Biotypes, antibiotic resistance and plasmids coding for CFA/I and STa in enterotoxigenic Escherichia coli strains of serotype O153:H45 isolated in Spain.
Enterotoxigenic Escherichia coli (ETEC) strains of serotype O153:H45 have been found recently to be a frequent cause of sporadic cases and outbreaks of neonatal diarrhoea in Spain and the most important cause of infant diarrhoea in Chile. Relationships between sugar fermentation patterns, resistance to antibiotics and plasmid profiles were analysed in nine E. coli O153:H45 strains isolated in Spain that synthesised CFA/I antigen and STa enterotoxin. Derivative strains obtained by curing with acridine orange, and transconjugants rendered antibiotic resistant, were characterised phenotypically and analysed for plasmid content. Two fermentation patterns were recognised: rhamnose fermenters (four strains) and rhamnose non-fermenters (five strains). The ability to ferment rhamnose was the only differential characteristic found among 49 carbohydrate fermentation tests used to establish fermentation patterns. All nine strains possessed similar plasmid profiles of three or four plasmids of 52-87 Mda. A non-conjugative large plasmid of 82 Mda or 87 Mda, depending upon the strain, was identified as that responsible for production of both CFA/I and STa. Resistance to antibiotics was determined by plasmids other than those coding for CFA/I and STa. Two conjugative resistance factors were identified: a 52-Mda plasmid coding for resistance to ampicillin, streptomycin and sulphonamide in rhamnose-fermenting strains, and a 77-Mda plasmid coding for resistance to ampicillin, streptomycin, kanamycin, tetracycline and sulphonamide in rhamnose non-fermenting strains. Our results support the hypothesis that the prevalence and distribution of ETEC strains belonging to serotype O153:H45 in Spain and Chile could be due to the extensive cultural relations between Spain and South American from the past.
Anti-Bacterial Agents↗
Virulent Escherichia coli strains for chicks bind fibronectin and type II collagen.
125I-fibronectin and 125I-collagen (type II) binding was detected in Escherichia coli strains isolated from chickens and poults. High fibronectin binding-strains also bind the 29 kD aminoterminal fragment of fibronectin. Binding properties in strain CK28 were partially characterized. The highest binding of 125I-fibronectin and 125I-collagen for strain CK28 was obtained with bacteria grown at 33 degrees C. Binding of 125I-fibronectin, its 125I-29 kD fragment, and 125I-collagen, was very rapid, reaching a maximum in 5 min. Binding of 125I-fibronectin and 125I-collagen was considerably inhibited by preincubation of bacteria with unlabelled fibronectin and unlabelled type I collagen respectively, but not inhibited with human immunoglobulin G or bovine serum albumin. Inhibition experiments showed that the reversibility of 125I-fibronectin binding was estimated at approximately 50%, while reversibility for 125I-collagen binding was higher than 90%. Receptors for fibronectin, its 29 kD fragment, and collagen were released from the bacterial surface by treatment at different temperatures, and surface material released at 100 degrees C inhibited binding. There was cross-inhibition for both fibronectin and collagen binding when unlabelled fibronectin and unlabelled collagen were used as inhibitors, suggesting that binding receptors for both proteins may be closely located.
Animals↗
Toxins and serotypes of faecal non-enterotoxigenic and non-enteropathogenic Escherichia coli strains causing mannose-resistant haemagglutination: relation with haemagglutination patterns.
Forty-three faecal non-enterotoxigenic and non-enteropathogenic human Escherichia coli strains causing mannose-resistant haemagglutination (MRHA) were tested for production of cytotoxic necrotizing factor (CNF), haemolysis (Hly), Verotoxin (VT) and lethal activity for mice. The serotypes of the strains were also determined. Of the total strains investigated, 49% synthesized CNF, 53% were haemolytic and 40% were lethal for mice. No strain producing VT was detected. Striking differences in the production of Hly and CNF were observed when MRHA strains were grouped according to their lethal or non-lethal activity. Thus, 82% of lethal strains produced Hly and/or CNF whereas only 35% (p less than 0.01) and 27% (p less than 0.01) of non-lethal strains produced Hly and CNF, respectively. The production of toxins was specially associated with strains possessing defined MRHA types. Thus, 100%, 82% and 50% of strains belonging to MRHA types III, IVa and V, respectively, were toxigenic, whereas no toxigenic strains from MRHA types IVb and VI were detected. The majority (77%) of MRHA strains possessed typical O groups usually reported to be present in pathogenic extraintestinal E. coli or in facultatively enteropathogenic E. coli. Furthermore, these O groups were more frequently detected in toxigenic (93%) than in non-toxigenic (47%) strains (p less than 0.01). Our results suggest that faecal non-enterotoxigenic E. coli strains belonging to MRHA types III, IVa and V may be responsible for extraintestinal infections as well as for sporadic intestinal infections, and that certain O groups are specially associated with E. coli strains belonging to particular MRHA types.
Animals↗
Relative cell surface hydrophobicity of Escherichia coli strains with various recognized fimbrial antigens and without recognized fimbriae.
Bacterial surface hydrophobicity as well as mannose-sensitive haemagglutinating (MSHA) and mannose-resistant haemagglutinating (MRHA) activities were studied in Escherichia coli strains with and without recognized fimbrial antigens grown under different conditions. Relative bacterial surface hydrophobicity was measured by the salt aggregation test. Four kinds of bacterial aggregations depending on fimbrial antigens were observed: bacteria with CFA/I, CFA/II, CFA/III and K88 aggregated in a particulated form, bacteria with type 1 pilus in a granular form, and bacteria with K99 in a tiny granular form. Some strains, mainly when grown under non-optimal conditions at 18 degrees C or when heated at 80 degrees C, aggregated in a non-typical filamentous form. Among MRHA- MSHA+ (type 1 pilus positive), two classes of bacteria were detected: hydrophobic bacteria aggregating in 0.2-0.4 M ammonium sulphate, and non-hydrophobic bacteria aggregating in 2.0 to 1.6 M ammonium sulphate. The hydrophobicity levels in strains possessing different recognized fimbrial antigens, when grown under optimal conditions to express fimbriae and their typical haemagglutination pattern, were of a decreasing order, viz. CFA/III = CFA/I greater than CFA/II greater than MRHA-MSHA+ hydrophobic = MRHA+ greater than P987 greater than K99-F41 = K88 greater than MRHA- MSHA+ non-hydrophobic greater than MRHA- MSHA- without recognized fimbriae.
Animals↗
Colonization antigens, antibiotic resistance and plasmid content of enterotoxigenic Escherichia coli isolated from piglets with diarrhoea in Galicia (north-western Spain).
Escherichia coli colonies isolated from 50 diarrhoeic and 29 healthy piglets were investigated for several properties related to pathogenicity, such as production of heat-labile (LT) and heat-stable (STa) enterotoxins, presence of K88 and K99 colonization antigens, mannose-resistant haemagglutinating activity (MRHA), beta-haemolysis and antibiotic resistance. The objective was to establish the toxic and adhesive abilities of E. coli strains that cause porcine diarrhoea in Galician farms. Fifty-seven colonies from 14 diarrhoeic piglets formed STa, while no STa+ colony was detected from healthy piglets. Thirty-four of the 57 STa+ colonies were resistant to gentamicin. Sixteen representative STa+ strains isolated from the 14 infected piglets were serotyped, investigated for plasmid content and examined by electron microscopy. Of these STa+ strains, 15 belonged to serotype 0141:K85ab and carried on their surface the fimbrial antigen P987. The remaining representative STa+ strain belonged to serotype 0101:K30 and was K99+, being the only STa+ strain with MRHA activity. All 15 STa+ P987+ strains possessed a similar plasmid pattern, with three plasmids ranging in molecular weight from 33 X 10(6) to 74 X 10(6); nine of the gentamicin-resistant strains possessed an additional plasmid of molecular weight 16 X 10(6), which was absent in the six gentamicin-sensitive strains. Strains producing LT or K88 antigen were not detected. Forty-one MRHA+ colonies were isolated at similar rates from both diarrhoeic and healthy piglets. Twelve of the 19 non-enterotoxigenic MRHA+ strains of which the O-group was established, belonged to serogroups (01, 02, 07, 08, 09 and 075) typical of the human E. coli strains that cause extraintestinal infections. Finally, a statistically significant association between haemolytic and MRHA activities in porcine E. coli was found. In conclusion, it was found that STa+ E. coli strains belonging to serotype 0141:K85ab:P987 are associated with porcine diarrhoea in Galicia. Additionally, no correlation between the isolation of non-ETEC MRHA+ strains and diarrhoea was observed.
Animals↗
Comparison between enterotoxic activity and methanol solubility in heat-stable enterotoxins (STa and STb) from Escherichia coli of human, porcine and bovine origins.
We have investigated the enterotoxic activity of culture filtrates and their methanol extracted fractions from 10 ST (STa or STb) producing Escherichia coli strains from human, porcine and bovine origin, in the infant mouse test (IMT) as well as in the rabbit intestinal loop test (RILT). Unconcentrated culture filtrates and methanol-soluble fractions from the eight STa-producing strains were positive in the IMT while methanol-insoluble fractions obtained from these STa-positive strains, like methanol-soluble and -insoluble fractions from the two strains producing only STb, lacked activity in the IMT. Unconcentrated culture filtrates from all ST-producing strains were unable to cause fluid accumulation in the rabbit ligated intestinal loops after 6 h incubation. When this material, concentrated 5-fold, was tested again, the culture filtrates and methanol-soluble fractions from all STa-producing strains yielded strongly positive fluid accumulation in the RILT, whereas culture filtrates and their methanol extracted fractions from the strains producing only STb, like methanol-insoluble fractions from four STa-producing strains, caused slight fluid secretion in the rabbit intestinal loops.
Animals↗
Association of melasma with thyroid autoimmunity and other thyroidal abnormalities and their relationship to the origin of the melasma.
Melasma is localized hyperpigmentation over the forehead, upper lips, cheeks, and chin. In this study, evidence suggesting an association between autoimmune thyroid disorders and melasma and the relationship of thyroid disorders to the origin of melasma is presented. A total of 108 nonpregnant women, aged 20-56 yr, were divided into 2 groups for the purpose of this study: 1) melasma, 84 patients; 2) control group, 24 patients from the Dermatology Clinic matched for age and sex. Microsomal thyroid autoantibodies (MCHA) were sought in all subjects. TRH-TSH tests were performed in patients with melasma and in those women with goiter and/or positive MCHA tests from the control group. Studies were completed with serum T4, T3, and antithyroglobulin antibody (TGHA) measurements in all patients with thyroid abnormalities. In patients with melasma, the frequency of thyroid disorders (58.3%) was 4 times greater than in the control group. The MCHA-negative patients had 1) simple goiter (13.1%), 2) Plummer's disease (2.4%), and 3) TSH hyperresponse to TRH in nongoitrous patients (10.7%). Patients with positive MCHA tests (32.1%) were divided into 2 subgroups. One comprised those women with an apparently normal thyroid gland and thyroid function (n = 7), while the other included all patients with goiter and/or subclinical hypothyroidism (n = 20). Regarding the origin of the melasma, it was found that 70% of women who developed melasma during pregnancy or while using oral contraceptives had thyroid abnormalities compared to 39.4% of patients with idiopathic melasma. Subjects from the control group had a 12.5% incidence of thyroid abnormalities, and only 8.3% had positive MCHA. Estrogen, progesterone, or both could be the triggering factor in the development of melasma in women who have a particular predisposition toward both melasma and thyroid autoimmunity. Patients with idiopathic melasma had a lower frequency of thyroid abnormalities, suggesting that there may be different genetic patterns linked to autoimmune thyroid disease. We conclude that there is a true association between thyroid autoimmunity and melasma, mostly in women whose melasma develops during pregnancy or after ingestion of oral contraceptive drugs.
Adult↗