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PubMed1997

Lack of relationship between the expression of Hsp27 heat shock estrogen receptor-associated protein and estrogen receptor or progesterone receptor status in male breast carcinoma.

Estrogen, through estrogen receptors (ERs), may regulate the synthesis of progesterone receptors (PRs) and of a heat shock estrogen receptor-associated protein (hsp27). In female breast carcinoma (FBC) both proteins serve as surrogate indicators for the presence of functional ERs. In addition, the expression of these proteins was related to other prognostic indicators of value in female breast tumours. Endocrine disorders, hormone therapy and altered estrogen metabolism have been associated with the development of male breast cancer (MBC), suggesting that evaluation of the expression of ER, PR and hsp27 might improve our understanding of the biology of this tumour. ER and PR status and hsp27 expression were evaluated by immunohistochemistry in 16 primary MBC patients. The interrelationships between these parameters were established and compared with the clinicopathological data on the tumours. Ten (56%) MBC patients were ER-positive, 69% were PR-positive and all samples were hsp27-positive. Our series of MBC patients showed a positive correlation between ERs and PRs, however there was a lack of correlation between hsp27 and ERs or PRs. MBCs did not exhibit any correlation between the biomarkers studied and known prognostic indicators for females (e.g. Scarff-Bloom-Richardson (SBR) or modified SBR (MSBR) grade, T stage, lymph node status). This is the first published series reporting the incidence of hsp27 in MBC. The lack of association between the expression of ERs and hsp27 found in MBC differs from the results reported for FBC, moreover the expression of ERs, PRs or hsp27 did not correlate with the clinicopathological parameters that have prognostic value in females. Although the data were obtained from a relatively small sample population, our findings suggest that MBC and FBC are biologically different tumours with respect to the expression of the studied proteins.

Adult↗
PubMed2000

Focal hepatic ablation using interstitial photon radiation energy.

BACKGROUND: Intratumoral ablative therapy is being used increasingly for the treatment of primary and secondary hepatic malignancies. The interstitial point-source photon radiosurgery system (PRS) is a novel ablative technique that uses radiation therapy similar in dosimetry to interstitial brachytherapy. STUDY DESIGN: To determine the feasibility, toxicity, and local tissue destructive capabilities of the PRS in the liver, preliminary studies in a nontumor-bearing canine model were examined. A 6-month survival study was conducted. Each animal received three radiation treatments, in the right, central, and left hepatic regions. Three low-dose treatments were delivered to each of six animals (group A), generating a 2.0-cm-diameter radiated sphere with a dose of 20 Gy at the lesion edge. Three high-dose treatments were delivered to each of six animals (group B), generating a 3.0-cm-diameter radiated sphere with 20 Gy at the lesion edge. RESULTS: The treatment reproducibly generated sharply demarcated hepatic ablative lesions proportional to the administered dose. Mean lesion diameter at 1 month was 1.6+/-0.2 cm in group A and 3.4+/-1.0 cm in group B. Lesion size was independent of intrahepatic location, including near vascular structures. PRS therapy, when applied to portal structures, resulted in hilar damage. Hilar damage appeared to be associated with arteriolar thrombosis and bile duct injury. Treatment of regions adjacent to large hepatic veins and the IVC was not associated with vessel thrombosis or stricture. CONCLUSIONS: PRS ablation is a generally well-tolerated method that results in consistent, well-demarcated, symmetric lesions of complete necrosis with minimal adjacent parenchymal injury. Application of such an approach for the treatment of liver tumors is promising.

Animals↗
PubMed2001

Interplay of the main chain, chiral side chains, and solvent in conformational transitions: poly([(R)-3,7-dimethyloctyl]-[(S)-3-methylpentyl]silylene).

Light scattering, sedimentation equilibrium, viscosity, circular dichroism (CD), and UV absorption (UV) measurements were made on dilute solutions of poly([(R)-3,7-dimethyloctyl]-[(S)-3-methylpentyl]silylene)(PRS) as functions of molecular weight. From light scattering and viscosity data, PRS is found to be a very stiff polymer of persistence length q as large as 103 nm at 25 degrees C, essentially a 7(3) helix found in the solid state; q increases only gradually with lowering temperature between -15 and 25 degrees C. The CD data show that PRS undergoes a conformational transition around 3 degrees C in isooctane (transition temperature T(c)). The CD signal is largely positive at low temperatures, passes through zero at T(c), and becomes largely negative at higher temperatures; T(c) is independent of sample's chain length N. This is a highly cooperative helix (M)-to-helix (P) transition depending remarkably on N, as PRS is substantially rodlike. The CD data are converted to the fraction f(P) of P helix as a function of N and analyzed successfully by a statistical mechanical theory based on a helix reversal model, where a polymer chain consists of M and P helices intervened by helix reversals, with the result that the free energy difference DeltaG(h) between P and M shows a temperature dependence similar to that of 2f(P) - 1, whereas the helix reversal energy is substantially constant at 1.2 x 10(4) J mol(-1); the latter value means that the helix reversal occurs only once in 100 Si units or less. This DeltaG(h) change and solvent dependence of T(c) are explained by a double-well potential for the rotation about Si-Si bonds, which incorporates into DeltaG(h) the solvent interactions with the helical grooves of side chains surrounding the main chain. Detailed features of UV absorption spectra at different temperature and molecular weights are also presented.

Journal Article↗
PubMed2006

Molecular basis of the recognition process: hydrogen-bonding patterns in the guanine primary recognition site of ribonuclease T1.

Investigation of the intrinsic H-bonding pattern of the guanine complex with a sizable segment (from Asn43 to Glu46) of the primary recognition site (PRS) in RNase T1 at the B3LYP/6-311G(d,p) level of theory enables the electronic density characteristics of the H-bonding patterns of the guanine-PRS complexes to be identified. The perfect H-bonding pattern in the guanine recognition site is achieved through the guanine complex interactions with the large segment of the PRS. Two significant short H-bonds, O epsilon 1...HN1 and O epsilon 2...HN2, have been identified. The similar short H-bond distances found in the anionic GC- base pair and in this study suggest that the short hydrogen-bond distances may be characteristic of the multiple H-bonded anionic nucleobases. The H-bonding energy distribution, the geometric analysis of the H-bonding pattern, and the electron structure characteristics of the H-bonds in the guanine PRS of RNase T1 all suggest that the O epsilon 1...HN1 and O epsilon 2...HN2 side-chain H-bonds dominate the binding at the guanine recognition site of RNase T1. Also, the geometry evidence, the electron structure characteristics, and the properties of the bond critical points of the H-bonds reveal that the side-chain H-bonding and the main-chain H-bonding are mutually intensifying. Thus the positive cooperativity between Asn43 to Tyr45 and Glu46 is proposed.

Binding Sites↗
PubMed2003

Expression profiling of human breast cancers and gene regulation by progesterone receptors.

Even the first expression profiling studies of breast cancers have generated new insights. They suggest for example, that information about tumor aggressiveness, prognosis, metastatic potential, or treatment outcome is encoded in, and can be deduced from, the primary tumor. On the other hand no clinical genomic array data have yet been published that deal with hormonal aspects of breast tumorigenesis, tumor progression, or therapeutics. Rather, studies have focused on experimental model systems. We review below the currently published data on array profiling in clinical breast cancer, then describe our studies in breast cancer cell lines and xenograft models dealing with progesterone receptors (PRs) and the role of progesterone. We demonstrate that the two PR isoforms, PR-A and PR-B, have mostly nonoverlapping molecular signatures when liganded by progesterone, with PR-B the more active form. Additionally, we document the surprising finding that unliganded PRs can regulate gene transcription, with PR-A the more active form. In ovariectomized mice supplemented with estradiol but lacking measurable progesterone, PR-B-expressing tumors grow to twice the size of PR-A-expressing ones. We conclude that in breast cancers, PRs are more than simple markers of estrogen receptor function. Rather, presence of PRs and the ratio of the two isoforms directly influence tumor phenotype, even in the absence of ligand.

Animals↗
PubMed2004

Production rates of cortisol in obesity.

OBJECTIVE: To determine the metabolic clearance rates (MCRs) and endogenous production rates (PRs) of cortisol (F) in grades 2 and 3 obese men (n = 9) and women (n = 6). RESEARCH METHODS AND PROCEDURES: The MCRs and the endogenous PRs of cortisol (F) were determined in grades 2 and 3 obese men (n = 9) and women (n = 6) using the stable isotope dilution technique and mass spectrometry. RESULTS: In obese women, endogenous PRs of F (0.6 +/- 0.4 mg/h) were similar to those of nonobese women, but MCRs of F were higher in obese women (9 +/- 4 L/h) compared with nonobese women (5 + 2 L/h; p < 0.05). The MCR of F was correlated with the ratio of excreted cortisone to F metabolites. Furthermore, obese women were characterized by an increased ratio of androsterone to etiocholanolone (p < 0.01). In obese men, the MCRs (11 +/- 6 L/h) and the endogenous PRs of F (0.6 +/- 0.3 mg/h) were both similar to those of nonobese men, but the MCR of F was directly correlated with the ratio of excreted cortisone to F metabolites (r = 0.7833, p = 0.012). DISCUSSION: These data demonstrate sex-specific differences in F metabolism in obesity. The rise in MCRs of F is more pronounced in obese women than in men. However, the increase in the MCR of F is moderate in both genders and exceeds the normal range only in a subgroup of obese individuals.

Adult↗
PubMed2026

All of Us diversity and scale yield context-dependent improvements in polygenic prediction.

Polygenic risk scores (PRSs) trained on multiancestry data can improve prediction in under-represented groups, but large linked genetic and health datasets capturing broad human diversity remain limited. Using 245,388 whole-genome sequences from the All of Us research program (AoU) together with UK Biobank data, we developed multiancestry PRSs for 32 traits and diseases. We evaluated how ancestry, methodology and genetic architecture influenced PRS performance across ancestrally diverse AoU participants. Increased diversity in the AoU improved PRS accuracy for several traits, especially in under-represented populations. However, maximizing sample size by meta-analyzing AoU and UK Biobank was not universally optimal: for less polygenic traits, AoU-only training performed best in African ancestry participants, consistent with ancestry-enriched effects. Individual PRS accuracy declined linearly with increasing ancestry divergence from the discovery GWAS, but this decay was attenuated using multiancestry training data. These findings underscore the value of more representative biobanks for equitable PRS performance.

Journal Article↗
PubMed2006

Early presynaptic changes during plasticity in cultured hippocampal neurons.

Long-lasting increase in synaptic strength is thought to underlie learning. An explosion of data has characterized changes in postsynaptic (pstS) AMPA receptor cycling during potentiation. However, changes occurring within the presynaptic (prS) terminal remain largely unknown. We show that appearance of new release sites during potentiation between cultured hippocampal neurons is due to (a) conversion of nonrecycling sites to recycling sites, (b) formation of new releasing sites from areas containing diffuse staining for the prS marker Vesicle-Associated Membrane Protein-2 and (c) budding of new recycling sites from previously existing recycling sites. In addition, potentiation is accompanied by a release probability increase in pre-existing boutons depending upon their individual probability. These prS changes precede and regulate fluorescence increase for pstS GFP-tagged-AMPA-receptor subunit GluR1. These results suggest that potentiation involves early changes in the prS terminal including remodeling and release probability increase of pre-existing synapses.

Animals↗
PubMed2006

Water drinking improves orthostatic tolerance in patients with posturally related syncope.

Water drinking improves OT (orthostatic tolerance) in healthy volunteers; however, responses to water in patients with PRS (posturally related syncope) are unknown. Therefore the aim of the present study was to examine whether water would improve OT in patients with PRS. In a randomized controlled cross-over fashion, nine patients with PRS ingested 500 ml and 50 ml (control) of water 15 min before tilting on two separate days. OT was determined using a combined test of head-up tilting and lower body suction and expressed as the time required to induce presyncope. We measured blood pressure and heart rate (using Portapres) and middle cerebral artery velocity (using transcranial Doppler). SV (stroke volume) and TPR (total peripheral resistance) were calculated using the Modelflow method. OT was significantly (P<0.02) greater after drinking 500 ml of water than after 50 ml (25.4+/-1.5 compared with 19.8+/-2.3 min respectively). After ingestion of 500 ml of water, blood pressure during tilting was higher, the tiltinduced reduction in SV was smaller and the increase in TPR was greater (all P<0.05). The correlation coefficient of the relationship between cerebral blood flow velocity and pressure was lower after 500 ml of water (0.43+/-0.1 compared with 0.73+/-0.1; P<0.05), indicating better autoregulation. In conclusion, drinking 500 ml of water increased OT and improved cardiovascular and cerebrovascular control during orthostasis. Patients with PRS should be encouraged to drink water before situations likely to precipitate a syncopal attack.

Adult↗
PubMed1996

Intragranular activation of bladder mast cells and their association with nerve processes in interstitial cystitis.

OBJECTIVE: To investigate the presence of progesterone receptors and the extent and type of degranulation exhibited by the increased numbers of mast cells (MCs) found in interstitial cystitis (IC), a painful bladder disorder which occurs almost exclusively in women, worsens perimenstrually and is characterized by increased numbers of oestradiol receptor (OR)-positive MCs. PATIENTS AND METHODS: The state of MC degranulation was analysed blindly using electron microscopy of bladder biopsies from 26 patients with IC and six control patients which included five women with incontinence, with none of the established characteristics of IC, and one man with transitional carcinoma of the bladder. Emphasis was placed on preserving the secretory granule ultrastructure. The presence of progesterone receptors (PRs) in five patients with IC and three controls was investigated using commercially available antibodies against PRs. RESULTS: Over 85% of bladder MCs expressed high affinity PRs, but the number of PR-positive MCs in patients with IC did not differ significantly from that of controls despite the overall increase in MCs seen in IC. MCs were activated to various degrees and were often near to neuronal processes. The secretory granule content of MCs from patients with IC was in different stages of dissolution, ranging from heterogeneous loss of electron density to the appearance of crystalline substructure and target forms containing only remnants of the original material. Typical degranulation by compound exocytosis was not observed. MCs from control patients contained secretory granules with mostly intact, electron-dense granules. CONCLUSION: These findings indicate that the symptoms of IC may depend on an imbalance of the relative number of oestrogen receptors (ORs) to PRs on bladder MCs resulting in a 'progesterone deficient' state. This possibility is strengthened by demonstration that oestradiol augments the secretion of MC histamine in response to the neuropeptide substance P, which is pro-inflammatory, nociceptive and overexpressed in bladders with IC. Intragranular activation of bladder MCs is a characteristic pathological finding in patients with IC. The lack of extensive degranulation, typically seen in anaphylaxis, may indicate a unique mode of stimulation and/or differential release of mediators.

Adult↗
PubMed2000

Effect of diabetes on some primitive reflexes.

Primitive reflexes (PRs) are present in newborns; they disappear as the brain matures and increase in frequency in healthy elderly individuals. Primitive reflexes are more frequent in some neurological disorders than in age-matched controls. The aim of this study was to investigate the effect of diabetes on some PRs. We examined three PRs (glabellar tap, snout and palmomental reflexes) in 376 subjects: 111 normal age-matched controls, 60 patients with cerebrovascular disease (CVD) and 205 patients with type 2 diabetes mellitus. The latter patients were divided into three groups: (1) diabetics without neurological complications (D); (2) diabetics with cerebrovascular disease (D-CVD); and (3) diabetics with polyneuropathy (D-PN). The frequency of PRs was increased in CVD, unchanged in D-CVD (except palmomental) and greatly reduced in D and D-PN. It is possible that the vascular lesions in perforating arteries of the pons in diabetic subjects, previously studied in some pathological reports, can account for the reduced occurrence of primitive reflex responses.

Aged↗
PubMed2003

Differences in hamstring muscle stretching of elite field hockey players and normal subjects.

OBJECTIVES: To investigate differences in stretching behaviour of hamstring muscles in elite field hockey players and normal subjects. METHODS: 16 normal healthy subjects (group A) and 16 elite field hockey players (group B). Stretching of the hamstrings was performed with a knee extension device. Two successive single stretches (1 and 2) until the maximum stretch tolerance was achieved were applied to each subject twice. Simultaneously range of movement (ROM), passive resistance to stretch (PRS) at 36 degrees ROM, and electromyographic (EMG) activity of the biceps femoris and semitendinosus muscles were recorded. RESULTS: ROM (p=0.02 for stretch 1; p=0.04 for stretch 2) and PRS (p=0.04 and p=0.03) were significantly higher in group B, as compared to group A. The EMG activity of the biceps femoris (p=0.02 for stretch 1; p=0.3 for stretch 2) and semitendinosus (p=0.03 and p=0.11) were significantly higher in group B only for stretch 1. From stretch 1 to 2, a significant increase in ROM was observed in both group A (p=0.002) and group B (p=0.0003), as well as a significant decrease of PRS (p=0.0002; p=0.002). EMG activity only showed a significant decrease in group B (biceps p=0.03;semitendinosus p=0.01), but not in group A (p=0.6; p=0.06). The EMG activity sets in when the subjects begin to perceptive pain in the stretched muscles. CONCLUSIONS: Significant differences exist. in the stretching behaviour of elite field hockey players and non-athletes. ROM, PRS and EMG activity are higher in athletes. Implications for treatment should be considered, but recommendations cannot be made on the basis of this study yet.

Adult↗
PubMed1984

The influence of plasma renin substrate on the relationship between plasma renin activity and plasma renin concentration. An experimental study in hyper- and hypothyroid rats.

The effects of endogenous Plasma Renin Substrate (PRS) on the relationship between Plasma Renin Activity (PRA) and the Plasma Renin Concentration (PRC) have been studied in hyperthyroid rats, by I-triiodothyronine (T3) administration and in hypothyroid rats, by propylthiouracil (PTU) treatment, to clarify if PRA changes are an adequate index for evaluating the renin-angiotensin changes during the alterations in the thyroid function. Although in experimental situations studied the induced variation on PRC explains a 62 per cent of the changes in PRA, finding a good lineal correlation between both parameters (r = 0.79, P less than 0.001). Not only does PRS play an important role on the kinetic of the enzymatic reaction but also explains jointly with PRC up to a 85 per cent of PRA alterations. PRS changes become more important during thyrotoxicosis where they limit in a higher degree the velocity of reaction due to inverse relationship between PRC and PRS (r = 0.74, P less than 0.001).

Angiotensinogen↗
PubMed1987

Soluble factors stimulating secretory protein translocation in bacteria and yeast can substitute for each other.

mRNA for prepro-alpha-factor (pp alpha), a yeast secretory glycoprotein, was translated in a wheat germ cell-free system that was posttranslationally supplemented either with inverted vesicles from the plasma membrane of Escherichia coli (INV) or with microsomes from Saccharomyces cerevisiae. A postribosomal supernatant (PRS) from E. coli was found to stimulate translocation of pp alpha across the INV membrane. A yeast PRS could substitute for its E. coli counterpart. Likewise, an E. coli PRS could substitute for a yeast PRS and stimulate translocation of pp alpha across yeast microsomal membranes.

Bacterial Proteins↗
PubMed1996

Comparative studies on the substrate specificity of avian myeloblastosis virus proteinase and lentiviral proteinases.

The retroviral proteinase (PR) seems to play crucial roles in the viral life cycle, therefore it is an attractive target for chemotherapy. Previously we studied the specificity of human immunodeficiency virus (HIV) type 1 and type 2 as well as equine infectious anemia virus PRs using oligopeptide substrates. Here a similar approach is used to characterize the specificity of avian myeloblastosis virus (AMV) PR and to compare it with those of the previously characterized lentiviral PRs. All peptides representing naturally occurring Gag and Gag-Pol cleavage sites were substrates of the AMV PR. Only half of these peptides were substrates of HIV-1 PR. The Km values for AMV PR were in a micromolar range previously found for the lentiviral PRs; however, the kcat values were in a 10 30-fold lower range. A series of peptides containing single amino acid substitutions in a sequence representing a naturally occurring HIV cleavage site was used to characterize the seven substrate binding subsites of the AMV PR. The largest differences were found at the P4 and P2 positions of the substrate. Detailed analysis of the results by molecular modeling and comparison with previously reported data revealed the common characteristics of the specificity of the retroviral PRs as well as its strong dependence on the sequence context of the substrate.

Amino Acid Sequence↗
PubMed1999

Genetic analysis and enzyme activity suggest the existence of more than one minimal functional unit capable of synthesizing phosphoribosyl pyrophosphate in Saccharomyces cerevisiae.

The PRS gene family in Saccharomyces cerevisiae consists of five genes each capable of encoding a 5-phosphoribosyl-1(alpha)-pyrophosphate synthetase polypeptide. To gain insight into the functional organization of this gene family we have constructed a collection of strains containing all possible combinations of disruptions in the five PRS genes. Phenotypically these deletant strains can be classified into three groups: (i) a lethal phenotype that corresponds to strains containing a double disruption in PRS2 and PRS4 in combination with a disruption in either PRS1 or PRS3; simultaneous deletion of PRS1 and PRS5 or PRS3 and PRS5 are also lethal combinations; (ii) a second phenotype that is encountered in strains containing disruptions in PRS1 and PRS3 together or in combination with any of the other PRS genes manifests itself as a reduction in growth rate, enzyme activity, and nucleotide content; (iii) a third phenotype that corresponds to strains that, although affected in their phosphoribosyl pyrophosphate-synthesizing ability, are unimpaired for growth and have nucleotide profiles virtually the same as the wild type. Deletions of PRS2, PRS4, and PRS5 or combinations thereof cause this phenotype. These results suggest that the polypeptides encoded by the members of the PRS gene family may be organized into two functional entities. Evidence that these polypeptides interact with each other in vivo was obtained using the yeast two-hybrid system. Specifically PRS1 and PRS3 polypeptides interact strongly with each other, and there are significant interactions between the PRS5 polypeptide and either the PRS2 or PRS4 polypeptides. These data suggest that yeast phosphoribosyl pyrophosphate synthetase exists in vivo as multimeric complex(es).

Gene Deletion↗
PubMed2000

Pyrogenic reactions associated with single daily dosing of intravenous gentamicin.

OBJECTIVE: To identify risk factors associated with an unexpected outbreak of pyrogenic reactions (PR) following intravenous gentamicin. DESIGN: We conducted two cohort studies. PRs were defined as chills, rigors, or shaking within 3 hours after initiating the gentamicin infusion during the preepidemic (December 1, 1997-January 15, 1998) or epidemic (May 1-June 15, 1998) periods. We tested gentamicin vials for endotoxin using the limulus amebocyte lysate assay. SETTING: Inpatient services of a large community hospital in Los Angeles, California. RESULTS: During the epidemic period, 22 (15%) of 152 patients developed documented PRs following intravenous gentamicin. PRs were more likely among patients receiving single daily dosing (SDD) than multiple daily dosing gentamicin (20/73 [27%] vs. 2/79 [3%]; relative risk, 10.8; 95% confidence interval, 2.6 44.7). Laboratory analysis of gentamicin vials found endotoxin levels that were higher among Fujisawa-brand gentamicin (implicated brand) than gentamicin used after the outbreak terminated (non-implicated brand). Although endotoxin levels in the vials did not exceed US Pharmacopeia limits (1.7 endotoxin units/mg gentamicin), the use of SDD gentamicin may place patients at greater risk of receiving doses of endotoxin above the threshold for PRs in humans. CONCLUSIONS: Reassessment of the acceptable amounts of endotoxin in gentamicin and other parenteral products should be considered when dosing intervals used in clinical practice change.

Adolescent↗
PubMed2000

Feasibility of ablating normal renal parenchyma by interstitial photon radiation energy: study in a canine model.

BACKGROUND AND PURPOSE: A miniature photon radiosurgery system (PRS) has been described as an alternative to surgical resection and external-beam radiation for tumors and may now offer an alternative for ablation of renal lesions. We evaluated the feasibility of ablation by PRS in a normal parenchyma canine model. MATERIALS AND METHODS: Twelve mongrel dogs were used in this survival study. In the left and right kidneys of each animal, a peripheral lesion and central-hilar lesion, respectively, were induced with PRS. The probes were placed in the renal parenchyma, and local radiation of 15 Gy at a radius of 1.3 cm was delivered over 10 minutes. Serum electrolytes were measured serially. Computed tomography scans were obtained, and the animals were sacrificed for pathologic correlation. In a separate study, the liver received three additional treatments of 10 to 20 minutes of radiation. RESULTS: Eleven dogs survived this 6-month study and were sacrificed as scheduled. One animal expired after 2 weeks from radiation-induced fulminant hepatic failure with normal renal function. No other complications were observed. The average lesion size was 2.5 cm in diameter. Histologic analysis confirmed coagulative necrosis with sharp demarcation from the surrounding parenchyma. CONCLUSION: Preliminary studies demonstrate the feasibility of PRS ablation of the renal parenchyma. Further tumor model testing will be important to determine the ultimate efficacy of local photon radiation energy.

Animals↗