Measures of body fatness and height in early and mid-to-late adulthood and prostate cancer: risk and mortality in The Pooling Project of Prospective Studies of Diet and Cancer.

BACKGROUND: Advanced prostate cancer etiology is poorly understood. Few studies have examined associations of anthropometric factors (e.g. early adulthood obesity) with advanced prostate cancer risk. PATIENTS AND METHODS: We carried out pooled analyses to examine associations between body fatness, height, and prostate cancer risk. Among 830 772 men, 51 734 incident prostate cancer cases were identified, including 4762 advanced (T4/N1/M1 or prostate cancer deaths) cases, 2915 advanced restricted (same as advanced, but excluding localized cancers that resulted in death) cases, 9489 high-grade cases, and 3027 prostate cancer deaths. Cox proportional hazards models were used to calculate study-specific hazard ratios (HR) and 95% confidence intervals (CI); results were pooled using random effects models. RESULTS: No statistically significant associations were observed for body mass index (BMI) in early adulthood for advanced, advanced restricted, and high-grade prostate cancer, and prostate cancer mortality. Positive associations were shown for BMI at baseline with advanced prostate cancer (HR = 1.30, 95% CI = 0.95-1.78) and prostate cancer mortality (HR = 1.52, 95% CI = 1.12-2.07) comparing BMI ≥35.0 kg/m2 with 21-22.9 kg/m2. When considering early adulthood and baseline BMI together, a 27% higher prostate cancer mortality risk (95% CI = 9% to 49%) was observed for men with BMI <25.0 kg/m2 in early adulthood and BMI ≥30.0 kg/m2 at baseline compared with BMI <25.0 kg/m2 in early adulthood and BMI <30.0 kg/m2 at baseline. Baseline waist circumference, comparing ≥110 cm with <90 cm, and waist-to-hip ratio, comparing ≥1.00 with <0.90, were associated with significant 14%-16% increases in high-grade prostate cancer risk and suggestive or significant 20%-39% increases in prostate cancer mortality risk. Height was associated with suggestive or significant 33%-56% risks of advanced or advanced restricted prostate cancer and prostate cancer mortality, comparing ≥1.90 m with <1.65 m. CONCLUSION: Our findings suggest that height and total and central adiposity in mid-to-later adulthood, but not early adulthood adiposity, are associated with risk of advanced forms of prostate cancer. Thus, maintenance of healthy weight may help prevent advanced prostate cancer.

Compromised BRCA1-PALB2 interaction is associated with breast cancer risk.

The major breast cancer suppressor proteins BRCA1 and BRCA2 play essential roles in homologous recombination (HR)-mediated DNA repair, which is thought to be critical for tumor suppression. The two BRCA proteins are linked by a third tumor suppressor, PALB2, in the HR pathway. While truncating mutations in these genes are generally pathogenic, interpretation of missense variants remains a challenge. To date, patient-derived missense variants that disrupt PALB2 binding have been identified in BRCA1 and BRCA2; however, there has not been sufficient evidence to prove their pathogenicity in humans, and no variants in PALB2 that disrupt either its BRCA1 or BRCA2 binding have been reported. Here we report on the identification of a novel PALB2 variant, c.104T>C (p.L35P), that segregates in a family with a strong history of breast cancer. Functional analyses showed that L35P abrogates the PALB2-BRCA1 interaction and completely disables its abilities to promote HR and confer resistance to platinum salts and PARP inhibitors. Whole-exome sequencing of a breast cancer from a c.104T>C carrier revealed a second, somatic, truncating mutation affecting PALB2, and the tumor displays hallmark genomic features of tumors with BRCA mutations and HR defects, cementing the pathogenicity of L35P. Parallel analyses of other germline variants in the PALB2 N-terminal BRCA1-binding domain identified multiple variants that affect HR function to varying degrees, suggesting their possible contribution to cancer development. Our findings establish L35P as the first pathogenic missense mutation in PALB2 and directly demonstrate the requirement of the PALB2-BRCA1 interaction for breast cancer suppression.

Expression and immunolocalisation of the endocytic receptors megalin and cubilin in the human yolk sac and placenta across gestation.

Megalin and cubilin are multifunctional endocytic receptors associated with many transporting epithelia. They play an essential role in transport of nutrients through the visceral yolk sac of rodents during embryogenesis. Here, we immunolocalise them to the endodermal layer of the human yolk sac, and to the syncytiotrophoblast and cytotrophoblast cells of placental villi. In villi, the protein level of both receptors increased with gestation. The mRNA for megalin remained constant, while that encoding cubilin increased with gestation. These results suggest megalin and cubilin may be important in human maternal-fetal transfer, and that they increase across gestation to facilitate this function.

The impact of the Orphan Drug Act on the development and advancement of neurological products for rare diseases: a descriptive review.

Many neurological diseases or conditions are rare disorders. The Orphan Drug Act (ODA) of 1983 was promulgated to promote the development of products for such conditions. In this Opinion piece, we discuss how the ODA has affected neurological diseases, note how current and future sponsors (any person(s) or entity (i.e., academic, corporate body, individual, manufacturer) that applies for an official regulatory action) of products for rare neurological diseases can take advantage of ODA incentives, identify areas of success and continuing needs, and review data that can help drive the future development of products for rare neurological conditions.

Ethanol-maintained responding of rats is more resistant to change in a context with added non-drug reinforcement.

Alternative non-drug reinforcers reliably decrease drug-maintained responding in self-administration procedures. Studies of the resistance to change of food-maintained behavior, however, have found that responding in the presence of a stimulus associated with an alternative reinforcer is more resistant to disruption. This increase in persistence occurs despite lower response rates when the alternative reinforcer is present. The present experiment examined if, in addition to decreasing response rates, an alternative non-drug reinforcer also increases the persistence of drug-maintained responding. Rats self-administered oral ethanol in a multiple schedule of reinforcement in which responding was reinforced in two components signaled by different stimuli. In one component, response-independent food was delivered in addition to the earned ethanol. The effects of the alternative food reinforcer on response rates and resistance to extinction in the two components were examined. As in previous experiments on the resistance to change of food-maintained operant behavior, response rates were lower, but more resistant to extinction in the presence of the stimulus associated with the alternative reinforcer. These findings suggest that all the reinforcers obtained in a context in which drugs are consumed may contribute to the persistence of drug seeking in that context. This increase in persistence may occur even if the alternative reinforcers interfere with drug seeking.

Effects of the xenoestrogen bisphenol A on expression of vascular endothelial growth factor (VEGF) in the rat.

Bisphenol-A (BPA) is used to produce polymers for production of polycarbonate and epoxy resins that are used in food containers and dental appliances. BPA binds to estrogen receptors and induces estrogenic activity in a number of biological systems. We recently reported that although Fisher 344 (F344) and Sprague-Dawley (S-D) rat strains exhibit different sensitivities to BPA at the level of vaginal epithelial cell proliferation, there was no difference in immediate early proto-oncogene expression between the two animal strains. In the present study we investigated the effects of BPA on expression of another estrogen-target gene, vascular endothelial growth factor (VEGF), in the uterus, vagina, and pituitary of F344 and S-D rats. Adult rats were ovariectomized and treated with BPA by intraperitoneal injection at concentrations of 0.02 to 150 mg/kg body wt. Expression of VEGF was monitored by RNase protection assay at 2 hr after treatment. There was a significant effect of dose of BPA on the type of VEGF isoform expressed in the uterus, vagina, and pituitary. BPA induced greater (P < 0.01) levels of VEGF164 and VEGF120+188 than VEGF110 levels. The lowest BPA dose that had a significant (P< 0.05) effect on VEGF expression compared with vehicle treatment was 37.5 mg/kg body wt.; dose-response curves did not differ between strains. This is the first report that the primary response of the uterus, vagina, and pituitary to BPA includes rapid induction of VEGF expression. Due to the capacity of VEGF to engage pleiotropic signaling pathways in other cellular systems, we suggest that modulation of VEFG may play a role in establishing the response of estrogen-target organs to estrogenic xenobiotics.

Estrogen receptor beta in the sheep ovary during the estrous cycle and early pregnancy.

Objectives were to sequence and examine the expression of the estrogen receptor beta (ERbeta) in the sheep ovary. The sequence of the ovine ERbeta (oERbeta) was determined using reverse-transcription polymerase chain reaction (RT-PCR) and cloning techniques. The reading frame of oERbeta contained 527 amino acids and exhibited high overall homology with cow (98%), rat (88%), and human (88%) ERbeta. In addition, an oERbeta isoform having a 139-base pair deletion (oERbeta1) was identified. The predicted amino acid sequence of this isoform is lacking the ligand-binding and carboxyl-terminal transactivation domains. The oERbeta protein and mRNA were determined in ovaries obtained from ewes on Days 0 (first day of estrus), 2, 6, and 10 of the estrous cycle and Day 30 of gestation. Immunohistochemistry showed that oERbeta protein was located in granulosa cells, the ovarian surface epithelium, endothelium, and Day 2 corpus luteum (CL). Weak immunostaining for ERbeta was detected in the theca interna. Relative steady-state amounts of oERbeta mRNA in the CL were determined using semiquantitative RT-PCR. Amounts of oERbeta mRNA were greater (P < 0.05) during CL formation (Day 2) than at later stages. The oERbeta to oERbeta1 mRNA ratio was lower (P < 0.05) on Day 2 than on Day 10 or Day 30 due to a decrease in amounts of oERbeta1. Results indicate that the oERbeta is a 527-amino acid protein expressed in specific cells of the ovary. Changes in relative amounts of full-length oERB and a deletion isoform in CL occurred during the estrous cycle, suggesting that these two types of ERbeta might regulate estrogen actions during early CL development in sheep.

Rapid changes in monoamine levels following administration of corticotropin-releasing factor or corticosterone are localized in the dorsomedial hypothalamus.

Monoaminergic systems are important modulators of the neuroendocrine, autonomic, and behavioral responses to stress-related stimuli. The male roughskin newt (Taricha granulosa) was used as a model system to investigate the effects of corticotropin-releasing factor (CRF) or corticosterone administration on tissue concentrations of norepinephrine, epinephrine, dopamine, 3,4-dihydroxyphenylacetic acid, serotonin, and 5-hydroxyindoleacetic acid (5-HIAA) in microdissected brain areas. Intracerebroventricular infusion of 25 or 50 ng of CRF increased locomotor activity and site-specifically increased dopamine concentrations within the dorsomedial hypothalamus 30 min after treatment when compared to vehicle-treated controls. In further studies, male newts were treated as follows: (1) no injection, no handling, (2) saline injection, or (3) 10 microg corticosterone and then placed in a novel environment. Monoamine and monoamine metabolite concentrations were similar in the unhandled and saline-injected controls 20 min after treatment. In contrast, corticosterone-injected newts had elevated concentrations of dopamine, serotonin, and 5-HIAA in the dorsomedial hypothalamus (a region that contains dopamine- and serotonin-accumulating neuronal cell bodies in representatives of all vertebrate classes) but not in several other regions studied. These site-specific neurochemical effects parallel neurochemical changes observed in the dorsomedial hypothalamic nucleus of mammals following exposure to a variety of physical and psychological stress-related stimuli. Therefore, these changes may reflect highly conserved, site-specific neurochemical responses to stress and stress-related neurochemicals in vertebrates. Given the important role of the dorsomedial hypothalamus in neuroendocrine, autonomic, and behavioral responses to stress, and a proposed role for this region in fast-feedback effects of glucocorticoids on the hypothalamo-pituitary-adrenal axis, these stress-related monoaminergic changes are likely to have important physiological or behavioral consequences.

Treadmill exercise training augments brain norepinephrine response to familiar and novel stress.

In a test of hypothalamic-pituitary-adrenal (HPA) cortical and hypothalamic-pituitary-gonadal (HPG) interaction during familiar and novel stress, we previously reported that treadmill exercise training led to blunted plasma adrenocorticotrophin (ACTH) response to acute treadmill running but a hyper-responsiveness of ACTH after novel immobilization. In this follow-up analysis, we examined whether those results might be plausibly explained by a similar effect of treadmill exercise training on increased levels of norepinephrine (NE) in hypothalamic and limbic brain regions which synergize to modulate the release of ACTH during stress. Ovariectomized Sprague-Dawley rats that had been exercise trained by treadmill running or remained sedentary for 6 weeks received intramuscular injections of estradiol benzoate (Eb) or sesame oil on each of 3 days prior to 15 min of familiar treadmill running or novel immobilization. Treadmill exercise training, regardless of Eb treatment or type of stress, increased NE levels in the paraventricular (PVN), arcuate, medial preoptic, and ventromedial areas of the hypothalamus and protected against depletion of NE in the locus coeruleus, amygdala, and hippocampus. We conclude that treadmill exercise training has a hyperadrenergic effect in brain areas that modulate hypothalamic regulation of ACTH release during stress that is independent of HPA-HPG interaction and novelty of the stressor. To help elucidate these findings, the effects of treadmill exercise training on A1-A2 nuclei which innervate the PVN and their relationship with the limbic and hypothalamic responses we report require study.

Immunohistochemical detection of estrogen receptor alpha in male rat spinal cord during development.

The alpha subtype of the estrogen receptor (ERalpha) is present in nociceptive and parasympathetic regions of the adult rat spinal cord. The pattern of ERalpha expression in the rat spinal cord during development, however, is unknown. We used a polyclonal antibody (ER-21) to examine the expression of ERalpha in male rat lumbosacral spinal cords at embryonic day (E) 17, E21 (the day before birth), postnatal day (P) 1 (the day of birth), P8, P17, P21, and P36. At E17, ERalpha immunoreactivity (ERalpha-ir) was observed predominantly in ependymal cells. Perinatally, ERalpha-ir was also present in neurons in dorsal root ganglia and in fibers capping and within laminae I and II. By P8, ERalpha-ir was absent in ependymal cells, but ERalpha-ir fibers were dense in laminae I and II and in sympathetic and parasympathetic areas. ERalpha-ir was also present in neurons in the dorsal horns. To determine whether ERalpha-ir fibers in laminae I and II were processes of spinal neurons or primary afferents, dorsal rhizotomies were performed on P17 and P21 animals. Unilateral transection of the lumbosacral dorsal roots virtually eliminated ERalpha-ir fibers in the ipsilateral superficial laminae, demonstrating that the majority of ERalpha-ir fibers in these laminae were primary afferents. We show for the first time that ERalpha-ir is present in neurons and fibers of male prenatal and postnatal spinal cord. The presence of ERalpha in neuronal nuclei and processes may reflect diverse roles and novel mechanisms of action for 17 beta-estradiol in development of spinal sensory and autonomic circuitry.

Measuring living standards with proxy variables.

Very few demographic surveys in developing countries have gathered information on household incomes or consumption expenditures. Researchers interested in living standards therefore have had little alternative but to rely on simple proxy indicators. The properties of these proxies have not been analyzed systematically. We ask what hypotheses can be tested using proxies, and compare these indicators with consumption expenditures per adult, our preferred measure of living standards. We find that the proxies employed in much demographic research are very weak predictors of consumption per adult. Nevertheless, hypothesis tests based on proxies are likely to be powerful enough to warrant consideration.

Effect of estradiol on estrogen receptor expression in rat uterine cell types.

In rodent uterus, both up- and down-regulation of estrogen receptor alpha (ERalpha) messenger ribonucleic acid (mRNA) and protein levels by estradiol has been demonstrated; however, it is not known which of the uterine compartments (endometrial epithelium, stroma, myometrium) respond to estradiol with autoregulation of ERalpha. The purpose of the present study was to investigate and compare the kinetics and cell type-specific effects of estradiol on uterine ERalpha expression in immature and adult rats. Ovariectomized female rats were injected s.c. with sesame oil or estradiol-17beta. Uteri were collected and analyzed for changes in ERalpha mRNA using RNase protection assays (RPA) and in situ hybridization using radiolabeled probes specific for ERalpha. Immunohistochemical analysis was performed with a polyclonal antibody specific to ERalpha. Expression of ERalpha in the uterine epithelial cells decreased at 3 and 6 h after estradiol administration to immature and adult rats, respectively. At 24 h, ERalpha mRNA levels in the immature and mature rat uterus were higher than pretreatment levels but returned to baseline by 72 h. Pretreatment with cycloheximide did not block the 3-h repressive effect of estradiol, suggesting that the estradiol-induced decrease in ERalpha mRNA occurs independent of new protein synthesis. A decrease in ERalpha mRNA and protein was also observed in uterine epithelia at 3 and 6 h after an estradiol injection to immature and adult rats, and intensity of both the in situ hybridization signal and the immunostaining in the epithelium increased at 24 and 72 h. However, the periluminal stromal cells in the adult uterus and the majority of stromal cells of the immature uterus appeared to have increased ERalpha expression. The results indicate that down-regulation of ERalpha in the epithelia and up-regulation of stromal ERalpha play a role in early events associated with estradiol-induced cell proliferation of the uterine epithelia.

Aromatase inhibition reduces dendritic growth in a sexually dimorphic rat spinal nucleus.

The rat lumbar spinal cord contains the steroid-sensitive spinal nucleus of the bulbocavernosus (SNB), whose motoneurons innervate perineal muscles involved in copulatory reflexes. In normal males, SNB motoneuron dendrites grow exuberantly through postnatal (P) day 28. This growth is steroid dependent: Dendrites fail to grow in males castrated at P7, but grow normally in castrates treated with testosterone or its metabolites, dihydrotestosterone combined with estrogen. Treatment with either metabolite alone supports dendritic growth, but not to the level of testosterone-treated or intact males. In this study, we tested the hypothesis that aromatization of androgens to estrogens was involved in the masculine development of SNB dendrites. Motoneuron morphology was assessed in normal males and males treated daily (P7-28) with fadrozole, a potent aromatase inhibitor (0.25 mg/kg, subcutaneously) or saline vehicle (n = 4-6/group). SNB motoneurons were retrogradely labeled with cholera toxin-horseradish peroxidase at P28 (when dendritic length is normally maximal) and reconstructed in three dimensions. Comparable labeling was seen across groups; it was equivalent in both the rostrocaudal and radial extents. However, dendritic lengths in fadrozole-treated males were significantly below those of intact or saline-treated males. Neither SNB somata size nor target muscle weight differed across groups. These results suggest that aromatization of androgens to estrogens is necessary for development of masculine SNB dendritic morphology.

Synergistic effects of testosterone metabolites on the development of motoneuron morphology in a sexually dimorphic rat spinal nucleus.

The rat lumbar spinal cord contains the testosterone-dependent spinal nucleus of the bulbocavernosus (SNB), whose motoneurons innervate perineal muscles involved in copulatory reflexes. In normal males, SNB dendrites grow exuberantly through the first 4 weeks postnatally. This growth is steroid-dependent: dendrites fail to grow in males castrated at P7, but grow normally in castrates treated with testosterone (T). Treatment with either of the T metabolites, dihydrotestosterone or estrogen, supports dendritic growth in castrates, but not to the lengths characteristic of intact males or T-treated castrates. The present study tested the hypothesis that dihydrotestosterone and estrogen act together to support development of SNB dendrites. Male rat pups were castrated on P7 and treated daily with dihydrotestosterone propionate (DHT) (2 mg), estradiol benzoate (E) (100 microg), DHT (2 mg) combined with estradiol benzoate in either 5 microg (E5) or 100 microg (E100) doses, or vehicle alone. On P28, when SNB dendritic length is normally maximal, motoneurons were retrogradely labeled with cholera toxin-HRP (BHRP). Soma size and dendritic lengths of labeled motoneurons were assessed and compared to those of age-matched, intact male rats. Soma areas of DHT + E5-treated and DHT + E100-treated castrates did not differ from those of castrates treated with DHT alone, although somata of all three groups were significantly larger than those of normal males and E- or oil-treated castrates. Dendritic lengths in DHT + E5-treated castrates were significantly shorter than those of normal males, and did not differ from those of castrates receiving DHT or E alone, although all hormone-treated groups had dendritic lengths that were significantly longer than untreated castrates. However, treatment of castrates with DHT + E100 fully supported dendritic growth to levels characteristic of normal males. These results suggest that somal and dendritic growth may occur through separate developmental mechanisms, and that E and DHT act synergistically to support normal masculine SNB dendritic development.

Activity wheel running reduces escape latency and alters brain monoamine levels after footshock.

We examined the effects of chronic activity wheel running on brain monoamines and latency to escape foot shock after prior exposure to uncontrollable, inescapable foot shock. Individually housed young (approximately 50 day) female Sprague-Dawley rats were randomly assigned to standard cages (sedentary) or cages with activity wheels. After 9-12 weeks, animals were matched in pairs on body mass. Activity wheel animals were also matched on running distance. An animal from each matched pair was randomly assigned to controllable or uncontrollable inescapable foot shock followed the next day by a foot shock escape test in a shuttle box. Brain concentrations of norepinephrine (NE), dopamine (DA), dihydroxyphenylacetic acid (DOPAC), 5-hydroxytryptamine (5-HT), and 5-hydroxyindole acetic acid (5-HIAA) were assayed in the locus coeruleus (LC), dorsal raphe (DR), central amygdala (AC), hippocampus (CA1), arcuate nucleus, paraventricular nucleus (PVN), and midbrain central gray. After prior exposure to uncontrollable foot shock, escape latency was reduced by 34% for wheel runners compared with sedentary controls. The shortened escape latency for wheel runners was associated with 61% higher NE concentrations in LC and 44% higher NE concentrations in DR compared with sedentary controls. Sedentary controls, compared with wheel runners, had 31% higher 5-HIAA concentrations in CA1 and 30% higher 5-HIAA concentrations in AC after uncontrollable foot shock and had 28% higher 5-HT and 33% higher 5-HIAA concentrations in AC averaged across both foot shock conditions. There were no group differences in monoamines in the central gray or in plasma prolactin or ACTH concentrations, despite 52% higher DA concentrations in the arcuate nucleus after uncontrollable foot shock and 50% higher DOPAC/DA and 17% higher 5-HIAA/5-HT concentrations in the PVN averaged across both foot shock conditions for sedentary compared with activity wheel animals. The present results extend understanding of the escape-deficit by indicating an attenuating role for circadian physical activity. The altered monoamine levels suggest brain regions for more direct probes of neural activity after wheel running and foot shock.

Preference for high- versus low-potency marijuana.

With many drugs of abuse, humans and other species display a preference for higher doses (or more potent dosage forms) over lower doses (or less potent dosage forms). The present study was designed to determine whether this generalization would hold for marijuana smoking by humans. Twelve regular marijuana smokers participated in two independent and identical choice trials in which, on separate sessions, they first sampled marijuana of two different potencies (0.63% and 1.95% delta-9-tetrahydrocannabinol; THC) and then, on the next session, chose which of the two, as well as how much, to smoke. During sampling sessions, the high-potency marijuana produced a greater heart rate increase and greater subjective effects than the low-potency marijuana. Subjects chose the high-potency marijuana significantly more often than the low-potency marijuana (21 out of 24 choice occasions). These results support the hypothesis that the reinforcing effects of marijuana, and possibly its abuse liability, are positively related to THC content.

Asymmetric performances in binaural localization of sound in space.

Twenty right-handers and 20 left-handers were tested on a sound localization task. Broadband noise was presented from either the left or right hemifield. Localization accuracy was significantly greater (P = 0.002) when sounds emanated from the left hemifield thereby suggesting a paramount role played by the right hemisphere. Correcting for front-rear reversals, attributable to impoverished spectral cues and/or faulty processing of such cues, rendered differences in error scores linked to hemifield nonsignificant. The data were interpreted to mean that the special contribution of the right hemisphere to this task was its greater fidelity in processing spectral cues. No differences in localization proficiency between right- and left-handers were observed.

Characterization of mRNAs and coding potential of the PET54 gene from Saccharomyces cerevisiae.

The nuclear PET54 gene in yeast controls expression of two mitochondrial genes: COX1 at the level of pre-mRNA splicing and COX3 at the level of mRNA translation. Two size classes (1.6 and 1.1 kb) of transcripts that contain the PET54 coding region are produced in vivo. Relative to the majority of yeast mRNAs analyzed so far, the 5' untranslated leader region of the 1.6 kb transcript is unusually long (254 bases), while that for the major 1.1 kb transcript is unusually short (1 base). The majority of each class of PET54 mRNA was associated with polysomes in vivo. The possibility that two polypeptides are produced in vivo from the 1.1 kb PET54 mRNA was raised by the work of Sedman et al. [J. Virol. 64: 453-457, 1990], which showed that translation initiation at a downstream AUG occurs with increased efficiency when the upstream AUG is located very close to the 5' end of the mRNA. However, two sensitive assays for production of a second polypeptide, which is predicted to be 22 kD, were employed and no second polypeptide was detected. Furthermore, a nonsense mutation introduced near the beginning of the PET54 open reading frame abolished both COX1 and COX3 gene expression. These results indicate that the PET54 gene encodes predominantly a single functional polypeptide that is employed for expression of both the COX1 and COX3 genes of mitochondrial DNA.

Determination of tretinoin in creams by high-performance liquid chromatography.

A stability indicating reversed-phase high-performance liquid chromatographic method has been developed to quantify tretinoin (all-trans-retinoic acid) in cream formulations. Tretinoin cream samples were dissolved directly in tetrahydrofuran and diluted for injection. Separation was accomplished on a 15 cm Nova-Pak C18 column using a tetrahydrofuran-phosphate buffer solvent system (42:58, v/v) and 1.0 ml/min flow-rate. The method is able to separate tretinoin from its degradation products formed under stressing conditions. Excellent precision and accuracy were found for the assay of tretinoin in the cream formulations.