Radiographic features associated with temporomandibular joint disorders among African, White, Chinese, Hispanic, and Indian racial groups.

CONTEXT: Various radiographic features have been associated with temporomandibular joint disorders (TMDs); however, these characteristics have not been compared among different racial groups. AIMS: To radiographically evaluate and compare craniofacial patterns and condylar findings suggestive of TMD among African, White, Chinese, Hispanic, and Indian racial groups. SETTINGS AND DESIGN: This multicenter retrospective study used data from three private orthodontic practices and a University Orthodontic Clinic. SUBJECTS AND METHODS: Panoramic and lateral cephalometric radiographs were collected from 250 subjects who were equally divided into five racial groups: Africans, Whites, Chinese, Hispanics, and Indians. All radiographs were initial records from patients seeking orthodontic treatment. Linear and angular cephalometric measurements were used to evaluate and compare cephalometric characteristics associated with TMD among groups. Panoramic radiographs were analyzed to compare the presence of condylar abnormalities and antegonial notching among groups. STATISTICAL ANALYSIS USED: One-way analysis of variance, followed by Tukey's test. RESULTS: African and Chinese groups had the smallest mean cranial base measurements, while the Indians had the largest. The mean Y-axis value was significantly larger in the Chinese group compared with the other groups. Increased mandibular plane angles were seen in the Chinese and African patients, compared with subjects from other groups. The mean percentage of condylar anomalies was higher in the Chinese subjects compared with all other groups. CONCLUSIONS: Chinese patients presented with more radiographic features suggestive of TMD, whereas the Indians showed the least, compared with subjects from the White, Black, and Hispanic racial groups.

Transition experience of young adults with inflammatory bowel diseases (IBD): a mixed methods study.

BACKGROUND: Outcomes following transition can be poor; many young adults are ill prepared to take responsibility for their health care, older adolescents report incomplete understanding of medications, and parents remain largely responsible for their care. Good patient-provider relationships are associated with better adherence; however, the role of the relationship between post-transition patients and their providers has not been explored. The current study aimed to understand transition of young adults with inflammatory bowel diseases (IBD), the impact of the paediatric patient-provider relationship and what determines the adult patient-provider relationship. METHODS: This study examined the experience of young adults with Crohn's disease or ulcerative colitis (aged 18-30) after transition. Twenty-nine patients completed a 31-item online survey of their transition experience from paediatric to adult care. Responses were coded quantitatively and qualitatively, and qualitative responses were analysed by two independent raters. RESULTS: Positive themes regarding adult providers included independence, autonomy and trust, while negative themes included initial discomfort and confusing logistics. Five of six patients who reported 'terrifying' first visit experiences with their adult providers reported overall positive relationships. The earlier the diagnosis age, the less involved in medical decisions they were as an adult (r = 0.41, P = .03). Those who had a more positive experience with their paediatric providers were more likely to bring up confusion with their adult providers (r = .45, P = .04), and those who had a more positive experience with their adult providers were more likely to endorse collaborative medical decision-making (r = .57, P < .001). CONCLUSIONS: Patients diagnosed with IBD at a young age may need extra education and self-management strategies, as they were less likely to exhibit behaviours indicative of a successful transition to adult care. Additionally, transition programme development may benefit from the post-transition perspective across chronic illness populations.

Comparative linkage maps suggest that fission, not polyploidy, underlies near-doubling of chromosome number within monkeyflowers (Mimulus; Phrymaceae).

Changes in chromosome number and structure are important contributors to adaptation, speciation and macroevolution. In flowering plants, polyploidy and subsequent reductions in chromosome number by fusion are major sources of chromosomal evolution, but chromosome number increase by fission has been relatively unexplored. Here, we use comparative linkage mapping with gene-based markers to reconstruct chromosomal synteny within the model flowering plant genus Mimulus (monkeyflowers). Two sections of the genus with haploid numbers ≥ 14 have been inferred to be relatively recent polyploids because they are phylogenetically nested within numerous taxa with low base numbers (n=8-10). We combined multiple data sets to build integrated genetic maps of the M. guttatus species complex (section Simiolus, n=14) and the M. lewisii group (section Erythranthe; n=8), and then aligned the two integrated maps using >100 shared markers. We observed strong segmental synteny between M. lewisii and M. guttatus maps, with essentially 1-to-1 correspondence across each of 16 chromosomal blocks. Assuming that the M. lewisii (and widespread) base number of 8 is ancestral, reconstruction of 14 M. guttatus chromosomes requires at least eight fission events (likely shared by Simiolus and sister section Paradanthus (n=16)), plus two fusion events. This apparent burst of fission in the yellow monkeyflower lineages raises new questions about mechanisms and consequences of chromosomal fission in plants. Our comparative maps also provide insight into the origins of a chromosome exhibiting centromere-associated female meiotic drive and create a framework for transferring M. guttatus genome resources across the entire genus.

Cytoplasmic male sterility in Mimulus hybrids has pleiotropic effects on corolla and pistil traits.

The mechanisms underlying genetic associations have important consequences for evolutionary outcomes, but distinguishing linkage from pleiotropy is often difficult. Here, we use a fine mapping approach to determine the genetic basis of association between cytonuclear male sterility and other floral traits in Mimulus hybrids. Previous work has shown that male sterility in hybrids between Mimulus guttatus and Mimulus nasutus is due to interactions between a mitochondrial gene from M. guttatus and two tightly linked nuclear restorer alleles on Linkage Group 7, and that male sterility is associated with reduced corolla size. In the present study, we generated a set of nearly isogenic lines segregating for the restorer region and male sterility, but with unique flanking introgressions. Male-sterile flowers had significantly smaller corollas, longer styles and greater stigmatic exsertion than fertile flowers. Because these effects were significant regardless of the genotypic composition of introgressions flanking the restorer region, they suggest that these floral differences are a direct byproduct of the genetic incompatibility causing anther abortion. In addition, we found a non-significant but intriguing trend for male-sterile plants to produce more seeds per flower than fertile siblings after supplemental pollination. Such pleiotropic effects may underlie the corolla dimorphism frequently observed in gynodioecious taxa and may affect selection on cytoplasmic male sterility genes when they initially arise.

Expression of neuropeptide hormone receptors in human adrenal tumors and cell lines: antiproliferative effects of peptide analogues.

Peptide analogues targeting various neuropeptide receptors have been used effectively in cancer therapy. A hallmark of adrenocortical tumor formation is the aberrant expression of peptide receptors relating to uncontrolled cell proliferation and hormone overproduction. Our microarray results have also demonstrated a differential expression of neuropeptide hormone receptors in tumor subtypes of human pheochromocytoma. In light of these findings, we performed a comprehensive analysis of relevant receptors in both human adrenomedullary and adrenocortical tumors and tested the antiproliferative effects of peptide analogues targeting these receptors. Specifically, we examined the receptor expression of somatostatin-type-2 receptor, growth hormone-releasing hormone (GHRH) receptor or GHRH receptor splice variant-1 (SV-1) and luteinizing hormone-releasing hormone (LHRH) receptor at the mRNA and protein levels in normal human adrenal tissues, adrenocortical and adrenomedullary tumors, and cell lines. Cytotoxic derivatives of somatostatin AN-238 and, to a lesser extent, AN-162, reduced cell numbers of uninduced and NGF-induced adrenomedullary pheochromocytoma cells and adrenocortical cancer cells. Both the splice variant of GHRH receptor SV-1 and the LHRH receptor were also expressed in adrenocortical cancer cell lines but not in the pheochromocytoma cell line. The GHRH receptor antagonist MZ-4-71 and LHRH antagonist Cetrorelix both significantly reduced cell growth in the adrenocortical cancer cell line. In conclusion, the expression of receptors for somatostatin, GHRH, and LHRH in the normal human adrenal and in adrenal tumors, combined with the growth-inhibitory effects of the antitumor peptide analogues, may make possible improved treatment approaches to adrenal tumors.

Changing practice to improve pain control for renal patients.

Pain is a common symptom described by patients with end-stage kidney disease (ESKD) but remains ineffectively managed. The aim of this audit was to determine what proportion of these patients report pain, then introduce the use of an analgesic ladder adapted specifically for ESKD, and finally re-evaluate the prevalence of pain symptoms, looking for an improvement. A cohort of inpatients on the renal wards of a West London teaching hospital was studied. The number of patients reporting pain and the severity of their pain on a scale of 1-10 were recorded. A considerable number of patients were barred from participating because of a language barrier. Interpreters were introduced, and the phase was repeated. The World Health Organization (WHO) three-step analgesic ladder was adapted for patients with ESKD and introduced to medical staff on the renal wards. The number of patients reporting pain and the severity of their pain were re-recorded. There was a significant reduction in the number of patients reporting pain and the severity of their pain. Pain control in patients with ESKD is improved through the use of an adapted version of the WHO analgesic ladder. Strategies must be in place for effective communication with foreign patients.

Comparative effects of chemotherapeutic agents on the growth and survival of human adrenal carcinoma cells in culture.

Adrenocortical carcinoma is an uncommon malignancy that is usually fatal within a short time after diagnosis. We have investigated the effects on the growth and survival of SW-13 human adrenal carcinoma cells in culture of some currently used and some potentially new agents in the treatment of adrenal cancer. Established drugs tested were mitotane, cisplatin, etoposide, 5-fluorouracil, and suramin. Other agents studied included adenine arabinofuranoside, cytosine arabinofuranoside, 2-methoxyestradiol, and paclitaxel. The most potent chemotherapeutic agents in this system were paclitaxel and 2-methoxyestradiol, with EC (50) of 1.8x10 (-8) and 3.3x10 (-7) M, respectively. Cytosine arabinofuranoside and cisplatin both had the same EC (50) of 7.0x10 (-7) M, and etoposide 1.1x10 (-6) M. All the other agents tested required much higher doses for effect, including mitotane, the current most commonly used chemotherapy for adrenal cancer, with an EC (50) of 3.3x10 (-4) M. These data suggest that paclitaxel, 2-methoxyestradiol, and cytosine arabinofuranoside should be further evaluated for their potential in the chemotherapy of adrenal carcinoma.

Estrogen and progesterone lower cyclin B1 AND D1 expression, block cell cycle in G2/M, and trigger apoptosis in human adrenal carcinoma cell cultures.

The effects of 17 beta-estradiol and progesterone were evaluated separately and in combination, on the growth, survival, and cell cycle dynamics of SW-13 human adrenal carcinoma cells in culture. Both hormones significantly decreased cell survival, with dose response curves at four days demonstrating EC (50)s estimated at 1.2 x 10 (-5) M for 17 beta-estradiol and 4.8 x 10 (-6) M for progesterone. Flow cytometry studies of these cultures indicated a strong G2/M blocking effect of both steroids, either individually or in combination; the effects of progesterone and of both agents together were substantially greater than the effect with 17 beta-estradiol alone. The sub-G1 region of the flow cytometry profile was significantly enhanced by exposure to 17 beta-estradiol and even more by progesterone. Sub-G1 "apoptosis" was confirmed by fragmented and condensed nuclear chromatin staining using a standard DAPI fluorescence assay. The expression of the critical cell cycle regulatory proteins cyclin B1 and D1 were significantly decreased by each hormone, with the influence of progesterone again predominating. These data demonstrate that high doses of 17 beta-estradiol and progesterone have inhibitory and apoptotic effects on SW-13 human adrenal carcinoma cells IN VITRO. The observed effects are associated with declines in cyclin B1 and D1 expression as well as a block in G2/M.

High dose 17 beta-estradiol and the alpha-estrogen agonist PPT trigger apoptosis in human adrenal carcinoma cells but the beta-estrogen agonist DPN does not.

Previous studies have shown that high dose 17beta-estradiol (10 (-5) M) has a G2/M blocking effect in SW-13 human adrenal carcinoma cultures and strongly enhances apoptosis. To examine the differential effects of estrogen alpha and beta-receptors in this system, we incubated SW-13 cells with specific alpha- and beta-estrogen receptor agonists, PPT [4,4',4''-(propyl-[ (1)H]-pyrazole-1,3,5-triyl) trisphenol] and DPN [2,3-bis (4-hydroxyphenyl) propionitrile], respectively (each at 10 (-5) M). Flow cytometry was used to analyze the percentages of cells in various phases of the cell cycle [sub-G1 (apoptosis), G1, S, and G2/M] in each experimental condition. Exposure to 17 beta-estradiol for 48 hours increased apoptosis more than 5-fold (from 3.6+/-0.5 to 20+/-2.2% of cells; p<0.01). The alpha-estrogen agonist PPT had a similar effect, increasing apoptosis to 22+/-1.7% (p<0.01), but the beta-agonist DPN caused no change (3.6+/-0.5 vs. 3.9+/-0.8%). While estrogen and the alpha-estrogen agonist decrease apoptosis in this system, both of these compounds decreased the percentage of cells in G1 (from 59+/-1.4% for control to 34+/-2.3% for estrogen and 40+/-2.0% for PPT; p<0.01 for both agents relative to control); the beta-agonist again had no effect. Estrogen was also found to block the cell cycle in G2/M, increasing it from 15+/-0.4 to 21+/-1.0% of cells (p<0.01), but neither the alpha- nor beta-estrogen agonists had any effect at this point in the cell cycle, indicating that the influence of estrogen was not likely to be either alpha- or beta-receptor mediated. There was no apparent effect of any of these agents on DNA synthesis, as indicated by unchanged percentages of cells in S phase. These studies suggest that induction of apoptosis by estrogen in SW-13 human adrenal cortical carcinoma cultures is mediated by the alpha-receptor, but the G2/M blocking effect of estrogen is not likely to be related to either alpha or beta mechanisms.

Dentoalveolar changes related to mandibular forward growth in untreated Class II persons.

The purpose of this study was to investigate dentoalveolar changes related to mandibular forward growth in persons with Class II malocclusions. The longitudinal cephalometric films of 40 subjects with untreated Class II malocclusions from mean age 8.8 to 17.8 years (before and after pubertal growth) were analyzed and compared with the Bolton norms. There was no statistically significant difference in mandibular growth between the Class II samples and the Bolton norms upon cross-sectional comparison. In the Class II subjects, forward growth of the mandible was greater than that of the maxilla by 4.36 mm on average; the dentoalveolar complex moved forward relative to the maxillary basal bone (point A) 2.16 mm and moved backward relative to the mandibular basal bone (pogonion) 2.28 mm; a strong linear relationship (almost a 1:1 ratio) existed between mandibular forward growth and dentoalveolar complex movement (r = 0.881; y = 0.976 x + 0.183). Results indicated that the effect of forward growth of the mandible, which could potentially bring the lower dentition forward, vanished into the adaptation movements of the dentoalveolar complex through intercuspal locking. Disarticulating the occlusion to minimize the effects of the adaptive mechanism and taking advantage of normal mandibular forward growth could be fundamental biological bases in treating Class II malocclusions in growing patients.

Effects of marine sponge extracts on mitogen-activated protein kinase (MAPK/ERK(1,2)) activity in SW-13 human adrenal carcinoma cells.

Some species of marine sponge have been shown to produce metabolites with endocrine-altering and cell growth regulatory properties. Since cell division and differentiation are controlled, in part, by the mitogen-activated protein kinase-extracellular signal-regulated kinase (MAPK/ERK) cascade, we tested extracts (1.0mg/ml) from six shallow water marine species obtained in the Florida Keys for effects on MAPK/ERK(l,2) (sub-variant of EC 2.7.1.37) activity in incubations with SW-13 human adrenal carcinoma cells in culture. In these short-term incubations, extracts from two species, the purple bleeding sponge (Iotrochota birotulata) and the West Indian bath sponge (Spongia barbara), significantly inhibited MAPK/ERK(1,2) activity (to 51 and 44% of control levels, respectively) without altering cell survival. Western blots for phosphorylated and total ERK showed that ERK(2) predominated over ERK(1) by a factor of about 4:1 and that the phosphorylated forms of these isozymes were strongly suppressed by active extracts from both sponges. Another species, the green sponge (Haliclona veridis), whose extract has been shown previously to activate guanylate cyclase and to inhibit adenylate cyclase in a variety of mammalian tissues, was found not to affect MAPK/ERK(1,2) in human adrenal carcinoma cultures but did lyse and kill most of these cultured cells. Extracts from the sheepswool sponge (Hippospongia lachne) and the bleeding sponge (Oligoceras hemorrhages) did not significantly affect either MAPK/ERK(1,2) activity or the survival of attached cells. An extract from the fire sponge (Tedania ignis) did not alter MAPK/ERK(1,2) activity but did modestly decrease cell viability. These studies document for the first time species-specifc effects of marine sponge extracts on the MAPK/ERK(1,2) cascade and on the growth and survival of human adrenal carcinoma cells in culture.

Effects of androgens and estrogens and catechol and methoxy-estrogen derivatives on mitogen-activated protein kinase (ERK(1,2)) activity in SW-13 human adrenal carcinoma cells.

We tested the effects of 17beta-estradiol as well as its catechol- and methoxy-derivatives, two androgens (DHEA and testosterone), a glucocorticoid (cortisol), a mineralocorticoid (aldosterone), and progesterone on the activity of ERK(1,2), a key component of the ERK/MAPK enzyme phosphorylation cascade, in SW-13 human adrenal carcinoma cells. After a 24-hour exposure SW-13 cells incubated with 10(-5) M concentrations of 17beta-estradiol, its 2-hydroxy or its 2-methoxy derivative, all had elevated ERK activities (196%, 159%, and 275%, respectively) relative to control cells (p < 0.01). Incubation with testosterone resulted in 162% of control ERK activity (p < 0.01), whereas incubation with the far weaker androgen DHEA or with cortisol, aldosterone, or progesterone had no significant effects. These findings suggest sex steroid-specific influences in the induction or activation of signal transduction pathways known to play a crucial role in cellular proliferation and differentiation.

Inbreeding depression in two populations of Arenaria uniflora (Caryophyllaceae) with contrasting mating systems.

I used parallel family-structured crossing designs to investigate the relative performance of self and outcross progeny in selfing and predominantly outcrossing populations of the annual plant Arenaria uniflora. The selfer population experienced much lower inbreeding depression (delta = 0.05 +/- 0.02 SE) than the outcrossers (delta = 0.19 +/- 0.02 SE). The negative association between genetic load and selfing rate suggests that purgable partially recessive alleles are the primary source of inbreeding depression, as does its late expression in both populations. Inbreeding depression in the selfer population, which naturally consists of highly inbred lines, was used to calculate the mean dominance (h = 0.33) and incidence rate (U = 0.30) of deleterious mutations. In the outcrosser population, significant variation among individuals in the expression of inbreeding depression may reflect lineage-specific differences in inbreeding history or, more probably, random variation in mutational load. The low (<< 0.5) inbreeding depression of outcrossers suggests that the maintenance of a mixed mating system in some A. uniflora populations and the evolution of nearly cleistogamous self-pollination in others may reflect local pollinator-mediated selection for selfing rather than the constant 3:2 genetic advantage invoked by many models.

A genetic map in the Mimulus guttatus species complex reveals transmission ratio distortion due to heterospecific interactions.

As part of a study of the genetics of floral adaptation and speciation in the Mimulus guttatus species complex, we constructed a genetic linkage map of an interspecific cross between M. guttatus and M. nasutus. We genotyped an F(2) mapping population (N = 526) at 255 AFLP, microsatellite, and gene-based markers and derived a framework map through repeated rounds of ordering and marker elimination. The final framework map consists of 174 marker loci on 14 linkage groups with a total map length of 1780 cM Kosambi. Genome length estimates (2011-2096 cM) indicate that this map provides thorough coverage of the hybrid genome, an important consideration for QTL mapping. Nearly half of the markers in the full data set (49%) and on the framework map (48%) exhibited significant transmission ratio distortion (alpha = 0.05). We localized a minimum of 11 transmission ratio distorting loci (TRDLs) throughout the genome, 9 of which generate an excess of M. guttatus alleles and a deficit of M. nasutus alleles. This pattern indicates that the transmission ratio distortion results from particular interactions between the heterospecific genomes and suggests that substantial genetic divergence has occurred between these Mimulus species. We discuss possible causes of the unequal representation of parental genomes in the F(2) generation.

Evidence for Dobzhansky-Muller incompatibilites contributing to the sterility of hybrids between Mimulus guttatus and M. nasutus.

Both chromosomal rearrangements and negative interactions among loci (Dobzhansky-Muller incompatibilities) have been advanced as the genetic mechanism underlying the sterility of interspecific hybrids. These alternatives invoke very different evolutionary histories during speciation and also predict different patterns of sterility in artificial hybrids. Chromosomal rearrangements require drift, inbreeding, or other special conditions for initial fixation and, because heterozygosity per se generates any problems with gamete formation, F1 hybrids will be most infertile. In contrast, Dobzhansky-Muller incompatibilities may arise as byproducts of adaptive evolution and often affect the segregating F2 generation most severely. To distinguish the effects of these two mechanisms early in divergence, we investigated the quantitative genetics of hybrid sterility in a line cross between two members of the Mimulus guttatus species complex (M. guttatus and M. nasutus). Hybrids showed partial male and female sterility, and the patterns of infertility were not consistent with the action of chromosomal rearrangements alone. F2 and F1 hybrids exhibited equal decreases in pollen viability (> 40%) relative to the highly fertile parental lines. A large excess of completely pollen-sterile F2 genotypes also pointed to the segregation of Dobzhansky-Muller incompatibility factors affecting male fertility. Female fertility showed a pattern similarly consistent with epistatic interactions: F2 hybrids produced far fewer seeds per flower than F1 hybrids (88.0 +/- 2.8 vs. 162.9 +/- 8.5 SE, respectively) and either parental line, and many F2 genotypes were completely female sterile. Dobzhansky-Muller interactions also resulted in the breakdown of several nonreproductive characters and appear to contribute to correlations between male and female fertility in the F2 generation. These results parallel and contrast with the genetics of postzygotic isolation in model animal systems and are a first step toward understanding the process of speciation in this well-studied group of flowering plants.

Pollen discounting and the evolution of selfing in Arenaria uniflora (caryophyllaceae).

Although most models of mating system evolution assign a central role to the male transmission advantage of selfing genotypes, empirical data on the male fitness consequences of increased self-pollination are still uncommon. Here, I use measures of pollen import and export by focal plants in genotyped arrays to investigate the effects of floral morphology and pollination environment on self and outcross male function. Plants from an autogamous population of Arenaria uniflora (Caryophyllaceae) exhibit complete pollen discounting relative to closely related outcrossers, as do morphologically intermediate F1 hybrids between the two populations. However, the low cumulative male fitness of hybrids probably results from reduced pollen number or competitive ability, rather than a nonlinear relationship with floral morphology. When surrounded by selfers, plants from the outcrosser population self-fertilize at nearly the same rate as selfers (>80%), but have much lower self male fitness due to reduced fruit set. Because outcross siring success is also extremely low (<8%) in this treatment, these mate-limited outcrossers are at male fitness disadvantage to both pseudocleistogamous selfers and nonlimited outcrossers. The relative male fitness of plants with different mating systems appears dependent on the ecological context, as well as on morphological trade-offs.

Biosynthesis and metabolism of steroid hormones by human adrenal carcinomas.

Over a 15-year period, our university-based laboratory obtained 125 adrenal tumors, of which 15 (12%) were adrenal cortical carcinomas. Of these, 6 (40% of the carcinomas) occurred in patients with clear clinical manifestations of steroid hormone excess. Adrenal cortical carcinoma cells derived from the surgically resected tumors in 4 of these patients were isolated and established in primary culture. Radiotracer steroid interconversion studies were carried out with these cultures and also on mitochondria isolated from homogenized tissues. Large tumors had the lowest steroidogenic activities per weight, whereas small tumors had more moderately depressed enzyme activities relative to cells from normal glands. In incubations with pregnenolone as substrate, 1 mM metyrapone blocked the synthesis of corticosterone and cortisol and also the formation of aldosterone. Metyrapone inhibition was associated with a concomitant increase in the formation of androgens (androstenedione and testosterone) from pregnenolone. Administration of metyrapone in vivo before surgery in one patient resulted in a similar increase in plasma androstenedione, though plasma testosterone levels were not significantly affected. In cultures of two of four tumors examined, dibutyryl cAMP stimulated 11ss-hydroxylase activity modestly; ACTH also had a significant stimulatory effect in one of these tumors. Unlike results obtained with normal or adenomatous adrenal cortical tissues, mitochondria from carcinomatous cells showed a lack of support of either cholesterol side-chain cleavage enzyme complex or steroid 11ss-hydroxylase activity by Krebs cycle intermediates (10 mM isocitrate, succinate or malate). This finding is consistent with the concept that these carcinomas may tend to function predominantly in an anaerobic manner, rather than through the oxidation of Krebs cycle intermediates.

Alpha1 connexin 43 gap junctions are decreased in human adrenocortical tumors.

Gap junctional communication disorders have been implicated in the etiology of benign and malignant tumors. Understanding the type, distribution, and frequency of gap junctions in adrenal disorders should provide insight into the role of gap junctions in adrenal carcinogenesis as well as information that may be useful in developing improved diagnosis and treatment of adrenal diseases. Using immunocytochemical techniques, we have characterized and compared alpha1 connexins 43 gap junction protein levels in normal adrenal glands to those in benign and malignant adrenocortical human tumors. In addition, gap junction protein levels were studied in a human adrenal cancer cell line (H295). In both normal and neoplastic adrenal tissues, only alpha1 connexin 43 could be detected, whereas beta1 connexin 32 and beta2 connexin 26 were not found. In the normal adrenal gland, the zona fasciculata was demonstrated to have the highest number of gap junctions per cell (mean +/- SEM, 13.78 +/- 1.93). In contrast, in benign adrenocortical adenomas, the number of gap junctions per cell compared to that detected in normal adrenal glands was significantly reduced (mean +/- SEM, 4.6 +/- 1.17; P < or = 0.05), and the lowest number was found in malignant adrenocortical tumors (1.42 +/- 0.58; P < or = 0.05). Similarly, there were few or no alpha1 connexin 43 gap junctions in the H295 population. There was a progressive decrease in gap junction plaques in adrenocortical cancer cell populations compared to those in normal cell populations. Therefore, analysis of gap junction protein may be helpful for the differential diagnosis of benign and malignant adrenal tumors. The induction of gap junctions in malignant cells may provide a novel therapeutic strategy for adrenal cancer.