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S Rice

Publications and source records attributed to S Rice.

At least 37 records · Page 2Linked to original sources
PubMed2000

The effect of nonscreening smears on screening smear results: a statistical analysis with its implications for the NHS cervical screening programme.

This is a statistical analysis of individual NHS Cervical Screening Programme laboratories screening smear 'pick-up' rates (defined here as percentage low grade and percentage high grade of total adequate smears for ages 20-64 years derived from general practitioners and community clinics) in relation to their nonscreening smear workload proportion (here defined as percentage nonscreening smears of total laboratory workload from all sources for all ages). This was achieved by the use of three one way ANOVA models in order to receive a complete overview of the results. The models were applied to the following: (1) Laboratories with a total workload of less than 15000 general practitioner (GP) and community clinic smears; (2) laboratories with a total workload of greater than 15000 GP and community smears and; (3) all laboratories (i.e. a combination of 1 and 2). The 'test' groups within each of these models comprised three subgroups based on the percentage of laboratory workload that consisted of smears from a nonscreening source. This figure ranged from 2.8% to 82.6%. The subgroups were divided so as to contain approximately the same number of laboratories in each one (172 laboratories in total, 42 with workload < 15000 and 130 with > 15000). The results show that laboratories high and low grade pick-up rates have a positively correlated but variable relationship with the proportion of their workload that consists of nonscreening smears. The results show significance overall at the 5% level for high grade and the 10% level for low grade (high grade at P = 0.045 and low grade at P = 0.071). Significance for laboratories viewing less than 15000 screening smears at the 1% level (high grade P = 0.006 and low grade P = 0.005). They show no significance, however, for laboratories viewing more than 15000 screening smears (high grade P = 0.457 and low grade P = 0.622). There is an intriguing possibility that a greater exposure to abnormal smears results in a greater tendency to detect them. The current data provides no evidence to support the NHS Executive's use of 15000 as a designated figure when quality monitoring and service provision becomes a specific issue. The closure or amalgamation of laboratories with workloads less than this would appear to have no scientific evidence base.

Adult↗
PubMed2000

Gastric adenocarcinoma with a yolk sac component: a case report and review of the literature.

Gastric yolk sac tumors (YST) are very rare and are mainly reported in elderly people. We present a case of a 36-year-old man with a poorly differentiated gastric cancer showing a mixture of adenocarcinoma and yolk sac tumor that metastasized to Virchow's node. Both biopsies, Virchow's node and gastric tumor, contained areas of adenocarcinoma and yolk sac tumor that stained strongly positive for alpha fetoprotein (AFP) by the immunohistochemistry method. A high level of serum AFP (38,200 ng/mL) was also noted in this case. The response to chemotherapy in this case of mixed gastric yolk sac tumor and adenocarcinoma was not as favorable as would be expected in a pure primary germ cell tumor.

Adenocarcinoma↗
PubMed2000

Hematology analyzers.

Explore the source record for details and available documents.

Clinical Laboratory Information Systems↗
PubMed1999

A structural change in the kinesin motor protein that drives motility.

Kinesin motors power many motile processes by converting ATP energy into unidirectional motion along microtubules. The force-generating and enzymatic properties of conventional kinesin have been extensively studied; however, the structural basis of movement is unknown. Here we have detected and visualized a large conformational change of an approximately 15-amino-acid region (the neck linker) in kinesin using electron paramagnetic resonance, fluorescence resonance energy transfer, pre-steady state kinetics and cryo-electron microscopy. This region becomes immobilized and extended towards the microtubule 'plus' end when kinesin binds microtubules and ATP, and reverts to a more mobile conformation when gamma-phosphate is released after nucleotide hydrolysis. This conformational change explains both the direction of kinesin motion and processive movement by the kinesin dimer.

Adenosine Triphosphatases↗
PubMed1999

Quorum-sensing cross talk: isolation and chemical characterization of cyclic dipeptides from Pseudomonas aeruginosa and other gram-negative bacteria.

In cell-free Pseudomonas aeruginosa culture supernatants, we identified two compounds capable of activating an N-acylhomoserine lactone (AHL) biosensor. Mass spectrometry and NMR spectroscopy revealed that these compounds were not AHLs but the diketopiperazines (DKPs), cyclo(DeltaAla-L-Val) and cyclo(L-Pro-L-Tyr) respectively. These compounds were also found in cell-free supernatants from Proteus mirabilis, Citrobacter freundii and Enterobacter agglomerans [cyclo(DeltaAla-L-Val) only]. Although both DKPs were absent from Pseudomonas fluorescens and Pseudomonas alcaligenes, we isolated, from both pseudomonads, a third DKP, which was chemically characterized as cyclo(L-Phe-L-Pro). Dose-response curves using a LuxR-based AHL biosensor indicated that cyclo(DeltaAla-L-Val), cyclo(L-Pro-L-Tyr) and cyclo(L-Phe-L-Pro) activate the biosensor in a concentration-dependent manner, albeit at much higher concentrations than the natural activator N-(3-oxohexanoyl)-L-homoserine lactone (3-oxo-C6-HSL). Competition studies showed that cyclo(DeltaAla-L-Val), cyclo(L-Pro-L-Tyr) and cyclo(L-Phe-L-Pro) antagonize the 3-oxo-C6-HSL-mediated induction of bioluminescence, suggesting that these DKPs may compete for the same LuxR-binding site. Similarly, DKPs were found to be capable of activating or antagonizing other LuxR-based quorum-sensing systems, such as the N-butanoylhomoserine lactone-dependent swarming motility of Serratia liquefaciens. Although the physiological role of these DKPs has yet to be established, their activity suggests the existence of cross talk among bacterial signalling systems.

4-Butyrolactone↗
PubMed1998

Delayed targeting of cytokine-nonresponsive human bone marrow CD34(+) cells with retrovirus-mediated gene transfer enhances transduction efficiency and long-term expression of transduced genes.

Primitive hematopoietic progenitor cells (HPCs) are potential targets for treatment of numerous hematopoietic diseases using retroviral-mediated gene transfer (RMGT). To achieve high efficiency of gene transfer into primitive HPCs, a delicate balance between cellular activation and proliferation and maintenance of hematopoietic potential must be established. We have demonstrated that a subpopulation of human bone marrow (BM) CD34(+) cells, highly enriched for primitive HPCs, persists in culture in a mitotically quiescent state due to their cytokine-nonresponsive (CNR) nature, a characteristic that may prevent efficient RMGT of these cells. To evaluate and possibly circumvent this, we designed a two-step transduction protocol using neoR-containing vectors coupled with flow cytometric cell sorting to isolate and examine transduction efficiency in different fractions of cultured CD34(+) cells. BM CD34(+) cells stained on day 0 (d0) with the membrane dye PKH2 were prestimulated for 24 hours with stem cell factor (SCF), interleukin-3 (IL-3), and IL-6, and then transduced on fibronectin with the retroviral vector LNL6 on d1. On d5, half of the cultured cells were transduced with the retroviral vector G1Na and sorted on d6 into cytokine-responsive (d6 CR) cells (detected via their loss of PKH2 fluorescence relative to d0 sample) and d6 CNR cells that had not divided since d0. The other half of the cultured cells were first sorted on d5 into d5 CR and d5 CNR cells and then infected separately with G1Na. Both sets of d5 and d6 CR and CNR cells were cultured in secondary long-term cultures (LTCs) and assayed weekly for transduced progenitor cells. Significantly higher numbers of G418-resistant colonies were produced in cultures initiated with d5 and d6 CNR cells compared with respective CR fractions (P < .05). At week 2, transduction efficiency was comparable between d5 and d6 transduced CR and CNR cells (P > .05). However, at weeks 3 and 4, d5 and d6 CNR fractions generated significantly higher numbers of neoR progenitor cells relative to the respective CR fractions (P < .05), while no difference in transduction efficiency between d5 and d6 CNR cells could be demonstrated. Polymerase chain reaction (PCR) analysis of the origin of transduced neoR gene in clonogenic cells demonstrated that mature progenitors (CR fractions) contained predominantly LNL6 sequences, while more primitive progenitor cells (CNR fractions) were transduced with G1Na. These results demonstrate that prolonged stimulation of primitive HPCs is essential for achieving efficient RMGT into cells capable of sustaining long-term in vitro hematopoiesis. These findings may have significant implications for the development of clinical gene therapy protocols.

Adult↗
PubMed1998

An intensive weight loss programme in established type 2 diabetes and controls: effects on weight and atherosclerosis risk factors at 1 year.

The efficacy, safety, and effect on cardiovascular risk factors of two intensive weight loss programmes in overweight Type 2 diabetic subjects were studied. The patients were recruited from hospital diabetic clinics and control obese subjects from the community. Obese (BMI >30) patients with Type 2 diabetes mellitus and controls were offered intensive conventional diabetic advice or a very low calorie diet. Weekly 2 h sessions were conducted in two day-room areas of adjacent medical wards of Torbay Hospital. Non-diabetic and diabetic very low calorie diet groups reduced BMI by 6 and 5 kg m(-2), respectively, at 1 year. Waist-hip ratios (-0.06 and -0.05) were also reduced (p = 0.04 and p = 0.01), while HDL/total cholesterol ratios increased (+0.04 and +0.06, p = <0.01). Transient changes in blood pressure and antioxidant vitamin status occurred in the intensive conventional diet group. Fourteen of diabetic very low calorie diet subjects discontinued insulin and oral hypoglycaemic agents for the whole year, and psychological well-being transiently improved. Substantial weight loss and improvement in cardiovascular risk factors could be maintained for 1 year in Type 2 diabetic patients by the use of a very low calorie diet.

Adult↗
PubMed1998

Transduction of recombinant human erythropoietin receptor cDNA into daughter progenitors derived from single CD34(3+) cord blood cells changes the differentiation profile of daughter progenitors.

In this study, we tested the capacity to change the differentiation profile of progenitor cells by retroviral-mediated transduction of EpoR cDNA into one of the paired daughter cells derived from single CD34(3+) CB cells. Our results show that for the non-viral-treated daughter cells, the majority (99.6%) formed the same colony type. However, with cells transduced with viral vectors, 7.1% of the daughter cells transduced with the EpoR cDNA formed either a burst forming unit-erythroid (BFU-E) or a colony-forming unit-granulocyte, macrophage, erythroid, megakaryocyte (CFU-GEMM) colony compared to the other daughter cell transduced with viral supernatant lacking EpoR cDNA, which formed either a colony-forming unit granulocyte-macrophage (CFU-GM) or a high proliferative potential-colony forming cell (HPP-CFC) colony. Expression of the transduced EpoR cDNA was confirmed in individual colonies by RT-PCR analysis. These results substantiate in a more rigorous fashion our previous results that it is possible to change the Epo-responsive differentiation profile of progenitor cells by transduction into these cells of an EpoR cDNA and this change was apparent only in daughter cells derived from single CD34(3+) kit+ cells transduced with EpoR cDNA.

Antigens, CD↗
PubMed1998

The myeloid zinc finger gene (MZF-1) delays retinoic acid-induced apoptosis and differentiation in myeloid leukemia cells.

The myeloid zinc finger gene, MZF-1, is a hematopoietic transcription factor expressed in developing myeloid cells. To characterize further the role of MZF-1 in myelopoiesis, we used retroviral gene transduction to overexpress MZF-1 in HL-60 cells to produce HL-60-MZF-1 cells. HL-60 cells respond to retinoic acid (RA) with growth inhibition, granulocytic differentiation and apoptosis. However, HL-60-MZF-1 cells exposed to RA continue to proliferate in response to RA as evidenced by a higher percentage of cells in S phase, higher peak cell counts, and later peak cell counts. Morphologic differentiation of the RA-induced HL-60-MZF-1 cells is delayed with half as many of the HL-60-MZF-1 cells compared to the wild-type HL-60 cells that are differentiated after 3 days of RA, although both cells types responded with 80-95% mature granulocytes after 6 days of RA. Apoptosis was delayed in the MZF-1 transduced cells as measured by internucleosomal DNA fragmentation patterns, the terminal transferase end labeling reaction (TUNEL), and quantitation of fragmented DNA by the diphenylamine reaction. Several markers of differentiation were identical in both HL-60 and HL-60-MZF-1 cells including CD11b, CD33, CD34, CD13, CD16 and CD14. However, following 6 days of RA, only half as many HL-60-MZF-1 cells expressed CD18 compared to the wild-type HL-60 cells. Expression of the bcl-2 proto-oncogene transcript and protein was higher in the HL-60-MZF-1 cells compared to wild-type HL-60s and expression persisted for 5 days following RA in the HL-60-MZF-1 cells compared to only 3 days in the parental HL-60 cells suggesting that bcl-2 may contribute to the inhibition of apoptosis. Overexpression of MZF-1 had no effect on PMA-induced monocyte/macrophage differentiation of HL-60 cells. Together these findings indicate that MZF-1 can stimulate cell proliferation and delay RA-induced differentiation and apoptosis in HL-60 cells. MZF-1 may function in a similar role in myelopoiesis allowing myeloid precursors to expand their numbers before going on to terminally differentiate.

Antineoplastic Agents↗
PubMed1998

Chronic myelogenous leukaemia CD34+ cells exit G0/G1 phases of cell cycle more rapidly than normal marrow CD34+ cells.

To investigate the mechanisms behind the leukaemic expansion of chronic myelogenous leukaemia (CML), we examined the cell cycle status and activation kinetics of purified subpopulations of CD34+ cells from normal and CML bone marrow (BM). Propidium iodide staining was used to assess cell cycle status of fresh cells or those stimulated with cytokines. Although the cell cycle status of fresh low-density cells from CML and normal BM was similar, a larger percentage of CML CD34+ cells were cycling than those from normal BM. The HLA-DR compartment of CML CD34+ cells, a fraction enriched for normal, non-leukaemic progenitors, contained a higher percentage of quiescent cells than the CD34+ HLA-DR+ fraction. When the activation of CD34+ cells was examined in response to SCF or IL-3 alone, or SCF+IL-3+IL-6, CML CD34+ cells exited GO/G1 more rapidly than normal CD34+ cells. Interestingly, although normal BM CD34+ cells failed to cycle in response to IL-6 alone, or in the absence of exogenous cytokines, 30% of CML cells cycled under these conditions. No differences in the degree of apoptosis were documented among CML and normal CD34+ cells in these cultures. These data suggest that enhanced cell cycle activation of CML CD34+ cells, by either autocrine stimuli or via enhanced sensitivity to exogenous stimuli, may be partially responsible for the pronounced cellular expansion characteristic of CML.

Adult↗
PubMed1998

Proliferation-induced decline of primitive hematopoietic progenitor cell activity is coupled with an increase in apoptosis of ex vivo expanded CD34+ cells.

We examined the decline in hematopoietic potential observed when human CD34+ cells are cultured in vitro by evaluating the association between proliferation history and the fate of long-term hematopoietic culture-initiating cells (LTHC-ICs) as well as the onset of programmed cell death. The membrane dye PKH2 was used to track ex vivo expanded human CD34+ cells from bone marrow, cord blood, and mobilized peripheral blood, and to identify and isolate CD34+ cells that had divided once, twice, three, or four times or more, as well as cells that had remained cytokine nonresponsive and therefore failed to proliferate. These isolated groups of cells were assayed for their hematopoietic potential, cell cycle status, and percentage of apoptotic cells. A gradual decline in the content of LTHC-ICs, as well as in their ability to initiate and sustain in vitro hematopoiesis, was found to correlate with the number of in vitro cellular divisions, such that the hematopoietic potential of CD34+ cells dividing four or more times was nearly depleted. DNA analysis revealed that cells dividing more than three times resided predominantly in G0/G1 phases of the cell cycle. In addition, the percentage of CD34+ cells undergoing apoptosis was found to increase concomitantly with the number of in vitro cellular divisions; less than 10% of cells dividing once were apoptotic, whereas more than 25% of CD34+ cells dividing four or more times underwent programmed cell death. Together, these data suggest that a proliferation-associated, and possibly activation-induced, loss of hematopoietic potential among dividing CD34+ cells may result from an increase in programmed cell death among dividing primitive hematopoietic progenitor cells.

Antigens, CD34↗
PubMed1998

The problem-based medical audit program: influence on family practice residents' knowledge and skills.

BACKGROUND AND OBJECTIVES: Family physicians need to possess the skills to conduct audits in their own clinical settings to ensure that their patients receive exemplary clinical care. Residency offers an important opportunity for physicians to develop these auditing skills. This study describes the introduction of a problem-based medical audit program at three teaching units in the Department of Family Medicine at McMaster University and the program's effect on learner knowledge, skills, and attitudes toward the practice audit. METHODS: A survey designed to assess residents' self-rated knowledge, skills, and attitudes toward practice audits was distributed before and after residents participated in the audit program. RESULTS: Forty-three residents were surveyed; 33 (76.7%) completed the initial questionnaire and follow-up questionnaire. Residents reported significant improvements in their understanding of the relevance of audits, ability to develop a practice audit question, skills in designing methodology, and skills needed to conduct an audit independently. Residents also reported a moderate increase in their knowledge of statistics needed to complete an audit. CONCLUSIONS: The practice audit program at McMaster University uses a problem-based model to introduce learners to the concept of the clinical audit. The practice audit program successfully improved the residents' self-reported ability to conduct an audit and heightened their understanding of the importance and relevance of the audit process.

Commission on Professional and Hospital Activities↗
PubMed1998

Assessment of proliferative and colony-forming capacity after successive in vitro divisions of single human CD34+ cells initially isolated in G0.

Exit of primitive hematopoietic progenitor cells (HPCs) from the G0 phase of the cell cycle in response to in vitro cytokine stimulation is a limiting step in successful ex vivo expansion. Simultaneous DNA/RNA staining with Hoechst 33342 and pyronin Y was used to separate human bone marrow CD34+ cells residing in G0 (G0CD34+) from those cycling in G1 and S/G2+M. Compared with CD34+ cells isolated in G1, G0CD34+ cells were characterized by a delayed response to cytokine stimulation and were enriched for long-term hematopoietic culture-initiating cells. We next compared the activation kinetics of individually sorted G0CD34+ cells stimulated with stem cell factor (SCF), flt3-ligand (FL), or interleukin-3 (IL-3) as single factors. In a novel clonal proliferation assay, the functional status of cells that had remained quiescent after an initial 7-day period and of those that had completed successive division cycles under each of these three factors was evaluated by assessment of subsequent proliferative capacity and maintenance of colony-forming cell precursor (pre-CFC) activity. All three cytokines were equally able to support the survival of primitive HPCs in the absence of cell division. Cells that did not respond to any cytokine stimulation for 7 days retained higher proliferative and pre-CFC activities than dividing cells. The hematopoietic function of cells that divided in response to SCF, FL, or IL-3 decreased after each division cycle. However, G0CD34+ cells displayed a heterogeneous response pattern to cytokine stimulation whereby SCF appeared to have a superior ability to promote the cycling of cells with high proliferative and pre-CFC activities. These results indicate that HPCs reside in opposing hierarchies of hematopoietic potential and responsiveness to cytokine stimulation. The data also begin to indicate relationships between cellular division in response to different stimuli and maintenance of hematopoietic function.

Adult↗
PubMed1997

Functional heterogeneity of human CD34(+) cells isolated in subcompartments of the G0 /G1 phase of the cell cycle.

Using simultaneous Hoechst 33342 (Hst) and Pyronin Y (PY) staining for determination of DNA and RNA content, respectively, human CD34(+) cells were isolated in subcompartments of the G0 /G1 phase of the cell cycle by flow cytometric cell sorting. In both bone marrow (BM) and mobilized peripheral blood (MPB) CD34(+) cells, primitive long-term hematopoietic culture-initiating cell (LTHC-IC) activity was higher in CD34(+) cells isolated in G0 (G0CD34(+) cells) than in those residing in G1 (G1CD34(+) cells). However, as MPB CD34(+) cells displayed a more homogeneous cell-cycle status within the G0 /G1 phase and a relative absence of cells in late G1 , DNA/RNA fractionation was less effective in segregating LTHC-IC in MPB than in BM. BM CD34(+) cells belonging to four subcompartments of increasing RNA content within the G0 /G1 phase were evaluated in functional assays. The persistence of CD34 expression in suspension culture was inversely correlated with the initial RNA content of test cells. Multipotential progenitors were present in G0 or early G1 subcompartments, while lineage-restricted granulomonocytic progenitors were more abundant in late G1 . In vitro hematopoiesis was maintained for up to 6 weeks with G0CD34(+) cells, whereas production of clonogenic progenitors was more limited in cultures initiated with G1CD34(+) cells. To test the hypothesis that primitive LTHC-ICs would reenter a state of relative quiescence after in vitro division, BM CD34(+) cells proliferating in ex vivo cultures were identified from their quiescent counterparts by a relative loss of membrane intercalating dye PKH2, and were further fractionated with Hst and PY. The same functional hierarchy was documented within the PKH2(dim) population whereby LTHC-IC frequency was higher for CD34(+) cells reselected in G0 after in vitro division than for CD34(+) cells reisolated in G1 or in S/G2 + M. However, the highest LTHC-IC frequency was found in quiescent PKH2(bright) CD34(+) cells. Together, these results support the concept that cells with distinct hematopoietic capabilities follow different pathways during the G0 /G1 phase of the cell cycle both in vivo and during ex vivo culture.

Antigens, CD34↗
PubMed1997

Orderly process of sequential cytokine stimulation is required for activation and maximal proliferation of primitive human bone marrow CD34+ hematopoietic progenitor cells residing in G0.

Bone marrow (BM) CD34+ cells residing in the G0 phase of cell cycle may be the most suited candidates for the examination of cell cycle activation and proliferation of primitive hematopoietic progenitor cells (HPCs). We designed a double simultaneous labeling technique using both DNA and RNA staining with Hoechst 33342 and Pyronin Y, respectively, to isolate CD34+ cells residing in G0(G0CD34+). Using long-term BM cultures and limiting dilution analysis, G0CD34+ cells were found to be enriched for primitive HPCs. In vitro proliferation of G0CD34+ cells in response to sequential cytokine stimulation was examined in a two-step assay. In the first step, cells received a primary stimulation consisting of either stem cell factor (SCF), Flt3-ligand (FL), interleukin-3 (IL-3), or IL-6 for 7 days. In the second step, cells from each group were washed and split into four or more groups, each of which was cultured again for another week with one of the four primary cytokines individually, or in combination. Tracking of progeny cells was accomplished by staining cells with PKH2 on day 0 and with PKH26 on day 7. Overall examination of proliferation patterns over 2 weeks showed that cells could progress into four phases of proliferation. Phase I contained cytokine nonresponsive cells that failed to proliferate. Phase II contained cells dividing up to three times within the first 7 days. Phases III and IV consisted of cells dividing up to five divisions and greater than six divisions, respectively, by the end of the 14-day period. Regardless of the cytokine used for primary stimulation, G0CD34+ cells moved only to phase II by day 7, whereas a substantial percentage of cells incubated with SCF or FL remained in phase I. Cells cultured in SCF or FL for the entire 14-day period did not progress beyond phase III but proliferated into phase IV (with <20% of cells remaining in phases I and II) if IL-3, but not IL-6, was substituted for either cytokine on day 7. G0CD34+ cells incubated with IL-3 for 14 days proliferated the most and progressed into phase IV; however, when SCF was substituted on day 7, cells failed to proliferate into phase IV. Most intriguing was a group of cells, many of which were CD34+, detected in cultures initially stimulated with IL-3, which remained as a distinct population, mostly in G0/G1, unable to progress out of phase II regardless of the nature of the second stimulus received on day 7. A small percentage of these cells expressed cyclin E, suggesting that their proliferation arrest may have been mediated by a cyclin-related disruption in cell cycle. These results suggest that a programmed response to sequential cytokine stimulation may be part of a control mechanism required for maintenance of proliferation of primitive HPCs and that unscheduled stimulation of CD34+ cells residing in G0 may result in disruption of cell-cycle regulation.

Adult↗
PubMed1996

Changing hospital practices to increase the duration of breastfeeding.

OBJECTIVE: To change the breastfeeding policy in a university teaching hospital in accord with the Ten Steps to Successful Breastfeeding of the United Nations Children's Fund and World Health Organization and to assess the impact of hospital practices on the duration of breastfeeding. METHODS: One hundred ninety-two and 392 postpartum women in a maternity ward were interviewed in 1990 and 1993, respectively, regarding how they were feeding their infants and feeding practices in the hospital. Between these two periods, the hospital infant-feeding policy was reviewed and revised in accord with the Ten Steps. Two hundred seventy of the mothers interviewed in 1993 were interviewed again when their infants were 4 months old regarding the duration of full and partial breastfeeding. RESULTS: By 1993, more newborns were put to the breast in the first hour of life (63.2% vs 24.8%); fewer breastfed infants were fed foods other than breast milk (27.9% vs 46.7%); and more mothers received breastfeeding guidance from hospital staff (81.9% vs 61.3%). The duration of breastfeeding in 1993 was longer for women who did not receive formula in the hospital, who were not given discharge packs containing formula and/or coupons, and who roomed-in more than 60% of the time. These associations persisted after controlling for confounding. CONCLUSION: Infant-feeding policies and practices are amenable to change, and policies such as the Baby-Friendly Hospital Initiative may contribute to an increase in the duration of breastfeeding.

Adult↗
PubMed1996

Effects of resistance training on bone mineral content and density in adolescent females.

Postmenarcheal adolescent girls performed resistance training (RT) for 26 weeks, which consisted of 4 sets of 13 exercises of varying and progressive intensity performed 3 times weekly on hydraulic resistance machines. Bone mineral was assessed by dual photon absorptiometry. Resistance training resulted in significant increases (pre-post) in biceps curl (21.4%), triceps press (21.5%), knee extension (25.1%), knee flexion (52.8%), and squat press (21.5%) strength. There were no significant differences between RT and control (C) groups initially, and no significant effects of training (pre-post) for total body (TB) or lumbar spine (LS) bone mineral content (BMC) or bone mineral density (BMD). The largest increases in LS bone mineral occurred during the first 13 weeks, and although not significant, the increases in LS BMC (g) (3.9 vs. 5.9%), LS BMC (g.cm-1) (2.6 vs. 5.9%), LS areal BMD (g.cm-2) (1.48 vs. 4.75%), and LS bone mineral apparent density (BMAD, g.cm-3) (0.47 vs. 4.13%) were greater in the RT compared with the C group during this period. In conclusion, resistance training resulted in a trend towards a transient increase in LS bone mineral during the first 13 weeks, but despite significant strength gains, there were no significant changes in TB or LS bone mineral after 26 weeks of training.

Adolescent↗