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Biomedical subjects

P H Watson

Publications and source records attributed to P H Watson.

At least 37 records · Page 2Linked to original sources

Histomorphometric evidence for increased bone turnover without change in cortical thickness or porosity after 2 years of cyclical hPTH(1-34) therapy in women with severe osteoporosis.

Parathyroid hormone (PTH) increases trabecular but may decrease cortical bone mass during treatment of postmenopausal osteoporosis. In a 2-year trial, PTH, with or without sequential calcitonin (CT), was given to 29 osteoporotic women (mean age 67 +/- 7 years), in 3-month cycles [28 days hPTH(1-34), 50 microg/day, +/-42 days CT, 75 units/day, 20 days "free"]. Over 2 years, lumbar spine bone mineral density measurements increased an average of 10%. Paired iliac crest biopsies were obtained 28 days and 2 years after starting the trial. The addition of CT made no difference to changes seen with cyclical PTH alone. Thus, the histomorphometric analyses for all 29 treated patients were compared with a separate group of biopsies from untreated osteoporotic control patients (n = 15). No significant increments in total bone volume or trabecular architecture were seen over 2 years of cyclical PTH treatment, although the light microscopic appearance of bone was normal. At the level of the bone remodeling unit, a twofold increase in total trabecular erosion surface over the control measurements was observed within the first 28 days of PTH treatment (10 +/- 5 vs. 5 +/- 3% trabecular surface, p < 0.01), which was sustained over 2 years. Trabecular bone formation rates (surface referent) were 11 +/- 7 microm(3)/microm(2)/year in control patients and threefold higher in treated patients both acutely (31 +/- 31 microm(3)/microm(2)/year, p < 0.01) and after 2 years (33 +/- 43 microm(3)/microm(2)/year, p < 0. 05). The activation frequency of trabecular remodeling was threefold higher than controls through 2 years of treatment (p < 0.05). The mean wall thickness of completed osteons after 2 years of treatment was significantly larger than controls (28 +/- 7 vs. 22 +/- 5 microm, p < 0.01), suggesting a positive remodeling balance, as well as the histomorphometric evidence of increased bone turnover and the increased resorption surfaces. Over 2 years of cyclical PTH therapy, cortical thickness remained significantly higher than controls (680 +/- 202 vs 552 +/- 218 microm, p < 0.05), without significant changes in cortical porosity. Thus, the histomorphometric changes during cyclical PTH therapy in patients with severe osteoporosis are consistent with increased trabecular bone turnover and a positive remodeling balance, with no evidence for detrimental changes in cortical bone.

Aged↗

Nuclear localization of the type 1 parathyroid hormone/parathyroid hormone-related peptide receptor in MC3T3-E1 cells: association with serum-induced cell proliferation.

We have recently demonstrated that the receptor for parathyroid hormone (PTH) and PTH-related peptide (PTHrP), PTHR, can be localized to the nucleus of cells within the liver, kidney, uterus, gut, and ovary of the rat. We set out to determine the localization of the PTHR in cultured osteoblast-like cells. MC3T3-E1, ROS 17/2.8, UMR106, and SaOS-2 cells were cultured in alpha-modified eagle medium containing 15% fetal calf serum under standard conditions. Untreated cells were grown on glass coverslips to 75-95% confluence and fixed in 1% paraformaldehyde. For experiments designed to examine cells synchronized by serum starvation, cells were grown on glass coverslips, starved of serum for 46 h, and then fixed at 2-h intervals for a total of 26 h after the addition of serum to the medium. Parallel sets of cells were pulsed with [3H]thymidine to track the DNA duplication interval. The PTHR was localized by immunocytochemistry using a primary antibody raised against a portion of the N-terminal extracellular domain of the PTHR. The results presented herein indicate that the PTHR attains a nuclear localization in each cell line examined. In UMR106 cells, PTHR immunoreactivity was restricted to the nucleolus. After cell synchronization, MC3T3-E1 cells double approximately 24 h after the addition of serum. Immunocytochemistry for the PTHR in these cells showed that the receptor staining is initially diffuse for the first 6 h, then becomes more perinuclear in distribution by 12-16 h. Nuclear localization of the receptor is achieved approximately 16-20 h after the addition of serum and remains there throughout the mitotic phase. Intense staining of mitotic and postmitotic cells was observed. No change in cell proliferation kinetics was observed in MC3T3-E1 cells cultured in the presence of 25 nM PTH(1-34). These data suggest an important role for the PTHR in the nucleus of MC3T3-E1 cells at the time of DNA synthesis and mitosis.

3T3 Cells↗

Altered expression of estrogen receptor-alpha variant messenger RNAs between adjacent normal breast and breast tumor tissues.

Using semiquantitative reverse transcription-polymerase chain reaction assays, we investigated the expression of variant messenger RNAs relative to wild-type estrogen receptor (ER)-alpha messenger RNA in normal breast tissues and their adjacent matched breast tumor tissues. Higher ER variant truncated after sequences encoding exon 2 of the wild-type ER-alpha (ERC-4) messenger RNA and a lower exon 3 deleted er-alpha variant (ERD3) messenger RNA relative expression in the tumor compartment were observed in the ER-positive/PR-positive and the ER-positive subsets, respectively. A significantly higher relative expression of exon 5 deleted ER-alpha variant (ERD5) messenger RNA was observed in tumor components overall. These data demonstrate that changes in the relative expression of ER-alpha variant messenger RNAs occur between adjacent normal and neoplastic breast tissues. We suggest that these changes might be involved in the mechanisms that underlie breast carcinogenesis.

Adult↗

Rapid small-animal dual-energy X-ray absorptiometry using digital radiography.

Although dual-energy X-ray absorptiometry (DEXA) is an established technique for clinical assessment of areal bone mineral density (BMD), the spatial resolution, signal-to-noise ratio, scan time, and availability of clinical DEXA systems may be limiting factors for small-animal investigations using a large number of specimens. To avoid these limitations, we have implemented a clinical digital radiography system to perform rapid area DEXA analysis on in vitro rat bone specimens. A crossed step-wedge (comprised of epoxy-based materials that mimic the radiographic properties of tissue and bone) was used to calibrate the system. Digital radiographs of bone specimens (pelvis, spine, femur, and tibia from sham-ovariectomized [SHAM] and ovariectomized [OVX] rats) were obtained at 40 kilovolt peak (kVp) and 125 kVp, and the resulting areal BMD values were compared with those obtained with a clinical fan-beam DEXA system (Hologics QDR 4500). Our investigation indicates that the cross-wedge calibrated (CWC) DEXA technique provides high-precision measurements of bone mineral content (BMC; CV = 0.6%) and BMD (CV = 0.8%) within a short acquisition time (<30 s). Areal BMD measurements reported by the CWC-DEXA system are within 8.5% of those reported by a clinical fan-beam scanner, and BMC values are within 5% of the known value of test specimens. In an in vivo application, the CWC-DEXA system is capable of reporting significant differences between study groups (SHAM and OVX) that are not reported by a clinical fan-beam DEXA system, because of the reduced variance and improved object segmentation provided by the CWC-DEXA system.

Absorptiometry, Photon↗

Nuclear localization of the type 1 PTH/PTHrP receptor in rat tissues.

The localization of PTH/PTH-related peptide (PTHrP) receptor (PTHR) has traditionally been performed by autoradiography. Specific polyclonal antibodies to peptides unique to the PTHR are now available, which allow a more precise localization of the receptor in cells and tissues. We optimized the IHC procedure for the rat PTHR using 5-microm sections of paraffin-embedded rat kidney, liver, small intestine, uterus, and ovary. Adjacent sections were analyzed for the presence of PTHR mRNA (by in situ hybridization) and PTHrP peptide. A typical pattern of staining for both receptor protein and mRNA was observed in kidney in cells lining the proximal tubules and collecting ducts. In uterus and gut, the receptor and its mRNA are present in smooth muscle layers (PTHrP target) and in glandular cuboidal cells and surface columnar epithelium. This suggests that PTH, or more likely PTHrP, plays a role in surface/secretory epithelia that is as yet undefined. In the ovary, PTHR was readily detectable in the thecal layer of large antral follicles and oocytes, and was present in the cytoplasm and/or nucleus of granulosa cells, regions that also contained receptor transcripts. PTHR protein and mRNA were found in the liver in large hepatocytes radiating outward from central veins. Immunoreactive cells were also present around the periphery of the liver but not within two or three cell layers of the surface. Clear nuclear localization of the receptor protein was present in liver cells in addition to the expected cytoplasmic/peripheral staining. PTHR immunoreactivity was present in the nucleus of some cells in every tissue examined. RT-PCR confirmed the presence of PTHR transcripts in these same tissues. Examination of the hindlimbs of PTHR gene-ablated mice showed no reaction to this antibody, whereas hindlimbs from their wild-type littermates stained positively. The results emphasize that the PTHR is highly expressed in diverse tissues and, in addition, show that the receptor protein itself can be localized to the cell nucleus. Nuclear localization of the receptor suggests that there is a role for PTH and/or PTHrP in the regulation of nuclear events, either on the physical environment (nucleoskeleton) or directly on gene expression.

Amino Acid Sequence↗

Estrogen receptor-alpha mRNA variants in murine and human tissues.

A side-by-side comparison of several normal mouse and human tissues was undertaken in order to determine if exon-deleted variant ER-alpha mRNAs are expressed in the mouse. The data showed that the complex pattern of ER-alpha alternative splicing that is detected in multiple human tissues was not apparent in murine tissues. Only low levels of an exon-4 deleted ER-alpha transcript were detected in murine tissues, although multiple relatively abundant exon-deleted ER-alpha transcripts were detected in human tissues. The data support a species-specific difference in the expression of ER-alpha variant mRNAs between mouse and human.

Alternative Splicing↗

Expression of the steroid receptor RNA activator in human breast tumors.

The expression of the recently described steroid receptor RNA activator (SRA) was measured by semiquantitative reverse transcription-PCR within 27 independent breast tumors, spanning a wide spectrum of grade and estrogen receptor (ER) and progesterone receptor (PR) levels. Subgroup analysis showed that SRA expression was similar in ER+/PR+ (median = 65.5, n = 8) and in ER-/PR- (median = 94.6, n = 5) tumors. Interestingly, SRA expression in these two subgroups was significantly (Mann-Whitney rank-sum test, P < 0.05) lower than that observed in ER+/PR- (median = 156.4, n = 6) and ER-/PR+ (median = 144.8, n = 8) tumors. A variant form of SRA, presenting a deletion of 203 bp within the SRA core sequence, was also observed in breast tumor tissues. The relative expression of this new SRA isoform correlated with tumor grade (Spearman coefficient r = 0.53, n = 27, P = 0.004). These data suggest that changes in the expression of SRA-related molecules occur during breast tumor progression.

Breast Neoplasms↗

Expression of estrogen receptor beta1, beta2, and beta5 messenger RNAs in human breast tissue.

A triple-primer PCR assay was developed, based on the coamplification of estrogen receptor (ER)-beta1, -beta2, and -beta5 cDNAs, to investigate the relative expressions of the corresponding mRNAs in breast cancer lines and in 53 independent breast tumors. The expression of ER-beta2 and ER-beta5 mRNAs was higher than that of ER-beta1 mRNA in both cancer cell lines and breast tumors. In breast tumors, increases in the ER-beta2:ER-beta1 and ER-beta5:ER-beta1 mRNA expression ratios were observed, which positively correlated with the level of tumor inflammation and tumor grade, respectively. A trend toward an increase of these ratios was also found in tumors, as compared to the normal adjacent breast tissue available for 13 cases. Our data suggest that changes in the relative expression of ER-beta1, -beta2, and -beta5 mRNAs occur during breast tumorigenesis and tumor progression.

Adult↗

Estrogen receptor-beta messenger RNA expression in human breast tumor biopsies: relationship to steroid receptor status and regulation by progestins.

When the level of estrogen receptor (ER)-beta mRNA in tumors, determined by reverse transcription-PCR, was assessed according to either ER status or PR status alone, determined by ligand binding assays, the level of ER-beta mRNA was significantly lower in PR+ tumors compared with PR- tumors (P = 0.036), and no association with ER status was found. Subgroup analysis showed that ER-beta mRNA expression in ER+/PR+ breast tumors was significantly less than in ER+/PR- (P = 0.009), ER-/PR+ (P = 0.029), and ER-/PR- (P = 0.023) groups. Interestingly, the ER-beta mRNA expression was specifically decreased by progestin in T47D breast cancer cells. The data suggest the possibility that expression of ER-beta in human breast tumors is a marker of endocrine therapy responsiveness.

Biopsy↗

Mammaglobin, a potential marker of breast cancer nodal metastasis.

The Mammaglobin gene, a breast-specific member of the uteroglobin gene family, has been previously identified as being overexpressed in some breast tumours, but the cellular origin and relationship to tumour progression are unknown. Using a subtractive hybridization approach, mammaglobin mRNA has also been found to be overexpressed in the in situ compared to the invasive element within an individual breast tumour. Further study by in situ hybridization performed in 13 breast tumours, selected to include normal, in situ, and invasive primary tumour elements, and in most cases axillary lymph node metastases, revealed that mammaglobin expression occurs in all elements, is restricted to epithelial cells, and is significantly increased in tumour cells compared with normal cells ( p< 0.04). Analysis of mammaglobin expression within 20 independent primary breast tumours and their corresponding axillary lymph nodes revealed that all 13 lymph nodes positive and none of the seven nodes negative for metastatic breast carcinoma by histology were mammaglobin-positive by reverse transcription-polymerase chain reaction (RT-PCR) ( p=0.0001). These results suggest that mammaglobin could be a marker of axillary lymph node breast metastases.

Adult↗

Psoriasin (S100A7) expression and invasive breast cancer.

Alteration of psoriasin (S100A7) expression has previously been identified in association with the transition from preinvasive to invasive breast cancer. In this study we have examined persistence of psoriasin mRNA and protein expression in relation to prognostic factors in a cohort of 57 invasive breast tumors, comprising 34 invasive ductal carcinomas and 23 other invasive tumor types (lobular, mucinous, medullary, tubular). We first developed an IgY polyclonal chicken antibody and confirmed specificity for psoriasin by Western blot in transfected cells and tumors. The protein was localized by immunohistochemistry predominantly to epithelial cells, with both nuclear and cytoplasmic staining, as well as occasional stromal cells in psoriatic skin and breast tumors; however, in situ hybridization showed that psoriasin mRNA expression was restricted to epithelial cells. In breast tumors, higher levels of psoriasin measured by reverse transcriptase-polymerase chain reaction and Western blot (93% concordance) were significantly associated with estrogen and progesterone receptor-negative status (P < 0.0001, P = 0.0003), and with nodal metastasis in invasive ductal tumors (P = 0. 035), but not with tumor type or grade. Psoriasin expression also correlated with inflammatory infiltrates (all tumors excluding medullary, P = 0.0022). These results suggest that psoriasin may be a marker of aggressive behavior in invasive tumors and are consistent with a function as a chemotactic factor.

Blotting, Western↗

Enhanced osteoblast development after continuous infusion of hPTH(1-84) in the rat.

Rats and humans respond to intermittent treatment with parathyroid hormone (PTH) with increased bone density and cancellous bone volume. In the rat, osteoblast expression of insulin-like growth factor-I (IGF-I) is elevated by intermittent PTH. We examined the effect of continuous infusion of rhPTH(1-84), a bone catabolic regime, on the IGF system in rat pelvis. Female Sprague-Dawley rats (12 weeks, 250 g) were randomly assigned to receive 0, 0.1, 1, or 5 microg/100 g body weight (b.w.) rhPTH(1-84) (0, 0.106, 1.06, or 5.305 nmol/kg) in vehicle (1% normal rat serum in saline) delivered by subcutaneous Alzet minipump. After 7 days, blood was taken for serum chemistry and pelvises were processed for immunocytochemistry. Sections of pelvis from rats continuously infused with 0.1 or 1 microg/100 g b.w. rhPTH(1-84) for 7 days did not differ significantly from those of the vehicle-treated controls. However, continuous infusion of 5 microg/100 g b.w. rhPTH(1-84) resulted in a dramatic increase in cellular development, with trabeculae surrounded by many layers of large, plump osteoblasts. All pelvis osteoblasts expressed osteocalcin, but only those from rats that received 0, 0.1, or 1 microg/100 g b.w. rhPTH(1-84) showed positive staining for IGF-I. The extra-abundant osteoblasts from rats that received 5 microg/100 g b.w. rhPTH(1-84) did not stain for IGF-I. However, although all osteoblasts stained positively for IGF binding proteins (IGFBPs)-3, -4, and -5, staining for these IGFBPs increased as the dose of rhPTH(1-84) (and osteoblast number) increased. These results suggest that continuous infusion of PTH has a direct effect on osteoblast development (either recruitment or proliferation), decreases the expression of IGF-I, and enhances the expression of IGFBPs in pelvis, factors which may interact to bring about negative bone balance.

Animals↗

Assessment of maintenance therapy with reduced doses of PTH(1-34) in combination with a raloxifene analogue (LY117018) following anabolic therapy in the ovariectomized rat.

This experiment was designed to evaluate the ability of a raloxifene analogue (RA), LY117018, with or without reduced dosing of human parathyroid hormone (hPTH)(1-34) to maintain gains in bone mass after a fully anabolic treatment regimen given to aging osteopenic rats. Six-month-old rats were ovariectomized (ovx) or sham-operated (sham). After 1 month, ovx rats were treated with an anabolic regimen consisting of subcutaneous hPTH(1-34) 80 microg/kg/day and oral raloxifene 3 mg/kg/day, each given 5 days/week for 3 months. Thereafter, the treated ovx rats went on to an 8 week maintenance phase of treatment with either RA alone at the same dose, hPTH(1-34) at a reduced dosing interval (twice a week), or a combination of the two. Bone mineral density (BMD) was measured ex vivo at four skeletal sites, lumbar spine (L2-4), proximal hemipelvis, whole femur, and tibia, by dual-energy X-ray densitometry. All four sites showed a similar pattern of response. After the 3 month anabolic phase, the sham group had significantly higher BMD values than ovx rats at all skeletal sites (p < or = 0.002). The ovx rats treated with PTH + RA during the anabolic phase of the protocol had significantly higher BMD than the sham group in the femur, tibia, and spine (p < or = 0.02) and higher but not significantly different values in the pelvis. Following the 2 month maintenance phase, comparisons were made with the PTH-RA group at the end of the anabolic phase. Decrements in BMD were seen in all three maintenance therapy groups, but they were not statistically significant in the RA plus reduced PTH dose group. However, reduced hPTH(1-34) dosing and RA alone resulted in significant reductions of bone mass measurements at several skeletal sites during the maintenance phase. We conclude that the raloxifene analogue LY117018 may be useful in maintaining bone mass in aging ovx rats following anabolic therapy with hPTH(1-34) and raloxifene analogue, but that this strategy only allows for dose reduction of hPTH(1-34) rather than its discontinuation.

Absorptiometry, Photon↗

Influence of estrogen receptor variants on the determination of ER status in human breast cancer.

Determination of estrogen receptor alpha (ER) status in breast cancer is an important predictive factor for clinical response to endocrine therapy. We have recently shown that discrepancies in ER status determined by immunohistochemical assay (ER-IHA) can occur between amino-terminal (1D5) and carboxyl-terminal (AER-311) targeted ER antibodies and that those tumors which demonstrate discordance are associated with increased expression of truncated ER variant mRNAs. In this study, we have explored this observation to examine if ER variant expression can exert a direct effect on ER-IHA or whether this association is attributable to the characteristics of the antibodies. ER negative cos-1 cells were transfected with expression vectors containing wild type ER (wt-ER) and/or a frequently expressed truncated variant, ER-clone-4 variant. We found that ER-IHA performed with the same N- and C-terminal targeting ER antibodies on cos-1 cells expressing wt-ER alone demonstrated no difference in signals by western blot (P > 0.1). However, co-expression of wt-ER and the truncated ER-clone-4 variant, resulted in discordant IHA results with relatively higher ER-IHA H-scores from N-terminal antibodies (P < 0.03). Furthermore, re-examination of a subset of breast tumors previously studied by ER-IHA showed persistent concordance in 4/5 cases and persistent differences in 3/5 cases with a different pair of ER antibodies. We conclude that the presence of truncated ER variant proteins can interfere with the interpretation of ER status determined by IHA and that this may account for some of the inconsistencies between ER status and response to endocrine therapy.

Antibodies, Neoplasm↗

Oestrogen receptor-alpha variant mRNA expression in primary human breast tumours and matched lymph node metastases.

We have shown previously that the relative expression of a truncated oestrogen receptor-alpha variant mRNA (ER clone 4) is significantly increased in axillary node-positive primary breast tumours compared with node-negative tumours. In this study, we have examined the relative expression of clone 4-truncated, exon 5-deleted and exon 7-deleted oestrogen receptor-alpha variant mRNAs in 15 primary breast tumour samples and in synchronous axillary lymph node metastases. Overall, there were no significant differences between the primary tumours and the matched metastases in the relative expression of these three specific variant mRNAs. Furthermore, the pattern of all deleted oestrogen receptor-alpha variant mRNAs appeared conserved between any primary and its matched secondary tumour.

Breast Neoplasms↗

Altered expression of exon 6 deleted progesterone receptor variant mRNA between normal human breast and breast tumour tissues.

The progesterone receptor (PR) is an important prognostic marker in breast cancer as well as a marker of responsiveness to endocrine therapies. The presence of several exon-deleted PR variant mRNAs in both normal and neoplastic breast samples has recently been reported. Amongst them, a variant mRNA deleted in exon 6 (D6-PR mRNA) that if translated would encode a truncated PR-like protein missing the hormone binding domain and one of the transactivating domains of the wild-type PR protein. In order to determine whether changes in D6-PR variant expression could occur during tumorigenesis, its expression was investigated by reverse transcription and polymerase chain reaction in ten normal reduction mammoplasty samples, nine breast tumours with high PR levels (> 100 fmol mg(-1) protein) and eight breast tumours with low PR levels (< 15 fmol mg(-1) protein), as determined by ligand binding assay. The relative expression of D6-PR to wild-type PR mRNA was lower (P< 0.01 ) in normal than in all tumour breast samples. Moreover, a trend to lower (P < 0.1) relative D6-PR expression was observed in high PR tumours, compared to low PR tumours. These data suggest that increased expression of D6-PR occurs during tumorigenesis.

Adult↗

The potential role for prolactin-inducible protein (PIP) as a marker of human breast cancer micrometastasis.

The prolactin-inducible protein (PIP/GCPD15) is believed to originate from a limited set of tissues, including breast and salivary glands, and has been applied as a clinical marker for the diagnosis of metastatic tumours of unknown origin. We have investigated the potential role of PIP mRNA as a marker of human breast cancer metastasis. Using reverse transcription polymerase chain reaction and Southern or dot blot analysis, PIP mRNA was detected in 4/6 breast cell lines, independent of oestrogen receptor (ER) status. In breast primary tumours (n = 97), analysed from histologically characterized sections, PIP mRNA was detected in most cases. Higher PIP mRNA levels correlated with ER+ (P = 0.0004), progesterone receptor positive (PR+) (P = 0.0167), low-grade (P = 0.0195) tumours, and also PIP protein levels assessed by immunohistochemistry (n = 19, P = 0.0319). PIP mRNA expression was also detectable in 11/16 (69%) of axillary node metastases. PIP mRNA expression, however, was also detected in normal breast duct epithelium, skin, salivary gland and peripheral blood leucocyte samples from normal individuals. We conclude that PIP mRNA is frequently expressed in both primary human breast tumours and nodal metastases. However, the presence of PIP expression in skin creates a potential source of contamination in venepuncture samples that should be considered in its application as a marker for breast tumour micrometastases.

Apolipoproteins↗

Classification of breast tumors by grade and steroid receptor status using pattern recognition analysis of infrared spectra.

Infrared (IR) spectroscopy applied to tissue sections yields complex spectra that provide a molecular fingerprint of the tissue. We have studied a cohort of 77 breast tumors by IR spectroscopy to develop an objective method for the assignment of grade of breast tumors. Although the major variations between spectra from different tumors were in absorptions arising from triglycerides (adipose tissue) and collagen, subtle changes in spectra could be detected that were independent of cellularity and tissue composition. Using a specific multivariate pattern recognition strategy to associate these changes in spectra with different tumor grades, we then were able to accurately reclassify tumors by grade (87% accuracy; kappa = 0.835). A similar approach allowed classification of steroid receptor status (93% accuracy; kappa = 0.852). We conclude that IR spectroscopy may have clinical utility in the objective assignment of breast tumor grade.

Breast Neoplasms↗