A simple volume related model of arterial blood pressure generation.

A single compartment model of the arterial circulation was used to generate an arterial blood pressure waveform from pre-determined stroke volume (SV) and arterial resistance (R). With fixed stroke volume and varying resistances blood pressure waveforms showed mean values proportional to resistance but amplitude lessening with higher pressure; the amplitude of the hypothetical volume waveform of the arterial system was the same for all resistance values. Where SV varied and R changed reciprocally, the waveform when analysed with the PulseCO algorithm gave estimates slightly higher than the input stroke volumes (r 0.9998; y = 0.99x + 5.28 ml). Where SV varied with fixed R mean blood pressure varied with stroke volume; SV estimates were, again, slightly higher than the input stroke volumes (r 0.9994; y = 0.986x + 6.04 ml). Estimates of SV and R from Valsalva manoeuvre BP were used in the model to generate arterial blood pressure. SV estimates closely resembled the original model values (r 0.988; y = 1.0802x - 3.9251). The model appears capable of generating BP waveforms compatible with real BP waveforms since stroke volume estimates closely resemble the original stroke volumes used in the model.

Characterization of newly established tumor lines from a spontaneous malignant schwannoma in F344 rats: nerve growth factor production, growth inhibition by transforming growth factor-beta1, and macrophage-like phenotype expression.

Transplantable tumor (KE) and clone cell (KE-F11) lines were established from a spontaneous malignant schwannoma found in an aged F344 rat. The primary tumor and KE tumors consisted of oval or spindle cells arranged in ill-defined bundles. Cultured KE-F11 cells exhibited polygonal or spindle configurations. Immunohistochemically, neoplastic cells in KE and KE-F11 reacted to vimentin, S-100 protein, neuron-specific enolase, myelin basic protein, and glial fibrillary acidic protein in varying degrees, indicating neurogenic features; occasional cells reacted to alpha-smooth muscle actin. Cells positive for lysosomal enzymes (acid phosphatase and non-specific esterase), and ED1 (rat macrophage specific) were observed in KE-F11, and electron microscopically, cells with many lysosomes were frequently present, indicating expression of macrophage-like phenotypes. Bioassay analysis revealed that KE-F11 cells produced high levels of nerve growth factor. DNA synthesis was inhibited by addition of transforming growth factor-beta1 (TGF-beta1), and Northern blot analysis revealed that expression of c-myc, a cell cycle-related immediate early gene, was depressed by TGF-beta1. Likely, TGF-beta1 is a factor capable of inhibiting cellular growth of Schwann cells. mRNA expression of the low-density lipoprotein receptor-related protein (LRP) was seen in KE-F11 cells by Northern blot analysis, and the level was decreased by lipopolysaccharide (LPS) treatment. LRP may be attributable to regulation of Schwann cell functions. KE-F11 cells seeded on laminin-coated dishes exhibited more extended cytoplasmic projections than on collagen type I-coated dishes. The present study provides evidence that biological properties of malignant schwannoma-derived cells might be affected by exogenous factors such as TGF-beta1, LPS and laminin. These tumor lines may be useful for studies on pathobiological characteristics of Schwann cells.

HACS1 encodes a novel SH3-SAM adaptor protein differentially expressed in normal and malignant hematopoietic cells.

SH3 and SAM domains are protein interaction motifs that are predominantly seen in signaling molecules, adaptors, and scaffold proteins. We have identified a novel family of putative adaptor genes that includes HACS1. HACS1 encodes a 441 amino acid protein that is differentially expressed in hematopoietic cells and has restricted expression in human tissues. Its SH3 domain is most similar to the same motif in Crk and its SAM domain shares homology with a family of uncharacterized putative scaffold and adaptor proteins. HACS1 maps to human chromosome 21q11.2 in a region that is frequently disrupted by translocation events in hematopoietic malignancies. Polyclonal antibodies against HACS1 recognized a 49.5 kDa protein whose mRNA is expressed in human immune tissues, bone marrow, heart, lung, placenta and brain. Cell lines and primary cells from acute myeloid leukemias and multiple myeloma patients express HACS1. Immunostaining and cellular fractionation studies localized the HACS1 protein predominantly to the cytoplasm.

Differential effects of transforming growth factor-beta1, a fibrogenic factor, on macrophage-like cells (HS-P) and myofibroblastic cells (MT-9) in vitro.

Transforming growth factor-beta1 (TGF-beta1) produced by infiltrating macrophages plays a role in fibrotic disorders through the induction of myofibroblasts. To explore possible mechanisms by which TGF-beta1 may act in this context, we investigated effects of TGF-beta1 on macrophage-like (HS-P) and myofibroblastic (MT-9) cells, two novel cell lines developed by us. Immunocytochemically, the addition of TGF-beta1 (0, 0.1, 0.5, and 1.0 ng/ml) dose-dependently suppressed the expressions of antigens recognized by macrophage/histiocyte-specific antibodies (ED1 and ED2) in HS-P cells, whereas the addition concomitantly increased the number of anti-alpha-smooth muscle actin antibody-positive myofibroblastic cells, suggesting a possible phenotypical modulation of macrophages into myofibroblasts in the fibrotic lesions. By contrast, MT-9 cells did not show such immunophenotypical changes following TGF-beta1 addition. DNA synthesis, measured by tritiated thymidine-incorporation, was inhibited in a dose-dependent manner in MT-9 cells by TGF-beta1 addition (0, 0.1, 0.2, 0.5, 1.0, 5, and 10 ng/ml), but that in HS-P cells was unchanged. Northern blot analysis revealed that expressions of cell cycle-related early genes, c-jun and c-myc, were increased in HS-P cells after TGF-beta1 (1 ng/ml) addition, with c-jun showing peak expression prior to c-myc. By contrast, the peak expressions of c-jun and c-myc were delayed in TGF-beta1 (1 ng/ml)-added MT-9 cells, and their levels were less in MT-9 cells than in HS-P cells. Furthermore, TGF-beta1 (1 and 10 ng/ml) induced DNA laddering in MT-9 cells, but did not in HS-P cells. Based on these findings, it was speculated that TGF-beta1 could have induced G1 arrest in cell cycle and apoptosis in MT-9 cells. The present study showed that there were significant differences in the effects of TGF-beta1 between macrophage-like HS-P cells and myofibroblastic MT-9 cells, presumably depending on divergent susceptibilities to TGF-beta1 between both cell types. Because such cell types are key cells in the fibrogenesis, HS-P and MT-9 might be useful models for investigating the pathogenesis of fibrosis in vitro.

Developmental expression of the TTX-resistant voltage-gated sodium channels Nav1.8 (SNS) and Nav1.9 (SNS2) in primary sensory neurons.

The development of neuronal excitability involves the coordinated expression of different voltage-gated ion channels. We have characterized the expression of two sensory neuron-specific tetrodotoxin-resistant sodium channel alpha subunits, Na(v)1. (SNS/PN3) and Na(v)1.9 (SNS2/NaN), in developing rat lumbar dorsal root ganglia (DRGs). Expression of both Na(v)1.8 and Na(v)1.9 increases with age, beginning at embryonic day (E) 15 and E17, respectively, and reaching adult levels by postnatal day 7. Their distribution is restricted mainly to those subpopulations of primary sensory neurons in developing and adult DRGs that give rise to unmyelinated C-fibers (neurofilament 200 negative). Na(v)1.8 is expressed in a higher proportion of neuronal profiles than Na(v)1.9 at all stages during development, as in the adult. At E17, almost all Na(v)1.8-expressing neurons also express the high-affinity NGF receptor TrkA, and only a small proportion bind to IB4, a marker for c-ret-expressing (glial-derived neurotrophic factor-responsive) neurons. Because IB4 binding neurons differentiate from TrkA neurons in the postnatal period, the proportion of Na(v)1.8 cells that bind to IB4 increases, in parallel with a decrease in the proportion of Na(v)1.8-TrkA co-expressing cells. In contrast, an equal number of Na(v)1.9 cells bind IB4 and TrkA in embryonic life. The differential expression of Na(v)1.8 and Na(v)1.9 in late embryonic development, with their distinctive kinetic properties, may contribute to the development of spontaneous and stimulus-evoked excitability in small diameter primary sensory neurons in the perinatal period and the activity-dependent changes in differentiation they produce.

Effects of lipopolysaccharide on a macrophage-like cell line (HS-P) from a rat histiocytic sarcoma.

Lipopolysaccharide (LPS) is a major modulator of macrophage functions. To characterize a newly established rat histiocytic sarcoma-derived cell line (HS-P), immunophenotypic changes and cellular growth responses of HS-P cells exposed to LPS were investigated and compared with those of MT-9 cells isolated from a rat malignant fibrous histiocytoma. MT-9 cells have somewhat histiocytic features, because occasional cells react to rat macrophage-specific antibodies. Addition of LPS to cultured HS-P cells increased the numbers of cells immunopositive to ED1 (rat macrophage-specific antibody) and ED2 (rat histiocyte-specific antibody) and stimulated the phagocytosis of latex beads, whereas LPS-treated MT-9 cells did not show such immunophenotypic changes. LPS-treated HS-P cells showed enhanced immunolabelling of alpha-smooth muscle actin, suggesting a possible modulation of macrophages towards myofibroblastic cells. To evaluate cellular growth after the addition of LPS or fetal bovine serum, DNA synthesis was examined by measuring tritiated thymidine incorporation, and the mRNA expression of c- jun and c- myc (immediate early genes in the cell cycle) was examined by Northern blot analysis. In HS-P cells, the addition of serum greatly increased DNA synthesis and induced high expression of c- jun and c- myc; in contrast, LPS markedly depressed DNA synthesis and reduced the expression of c- jun and c- myc. HS-P cells were more sensitive than MT-9 cells to the growth-promoting effect of serum and the growth-inhibiting effect of LPS. The study demonstrated that HS-P cells are highly LPS-responsive, indicating that they would be useful for studies of macrophage functions.

Divergent Pseudomonas exotoxin A sensitivity in normal and transformed liver cells is correlated with low-density lipoprotein receptor-related protein expression.

Pseudomonas exotoxin A (PEA) is an extracellular virulence factor produced by the opportunistic human pathogen Pseudomonas aerguinosa. PEA intoxification begins when PEA binds to the low-density lipoprotein receptor-related protein (LRP). The liver is the primary target of systemic PEA, due largely to the high levels of functional LRP expressed by liver cells. Using a 3H-leucine incorporation assay to measure inhibition of protein synthesis we have demonstrated that normal (BNL CL.2) and transformed (BNL 1ME A7R.1) liver cells exhibit divergent PEA sensitivity; with BNL 1ME A7R.1 cells demonstrating greater PEA sensitivity than their non-transformed counterparts. The receptor-associated protein, a LRP antagonist, decreased PEA toxicity in BNL 1ME A7R.1 cells, confirming the importance of the LRP in PEA intoxification in this cell type. Increased PEA sensitivity in BNL 1ME A7R.1 cells was associated with increased functional cell surface LRP expression, as measured by alpha2-macroglobulin binding and internalization studies, and increased LRP mRNA levels, as determined by Northern blot analysis. Interestingly, BNL CL.2 cells were more sensitive than BNL 1ME A7R.1 cells to conjugate and mutant PEA toxins that do not utilize the LRP for cellular entry. These data demonstrate that increased LRP expression is an important mechanism by which PEA sensitivity is increased in BNL 1ME A7R.1 transformed liver cells.

Application of the ethoxyresorufin-O-deethylase (EROD) assay to mixtures of halogenated aromatic compounds.

The ethoxyresorufin-O-deethylase (EROD) assay monitors the induction of the xenobiotic-metabolizing enzyme cytochrome P-450 (CYP) 1A1 and is a widely used biomarker for exposure of wildlife to substances that bind the aryl hydrocarbon (Ah) receptor. In this work the induction of EROD activity by single compounds and binary mixtures in primary rat hepatocytes was compared with the predictions of a kinetic model involving mixtures of inducers. The inducing agents were also examined for their ability to activate the Ah receptor to its DNA-binding form and for their ability to act as competitive inhibitors for CYP 1A1. Xenobiotics that failed to activate the Ah receptor did not induce EROD activity. Competitive inhibition for CYP 1A1 between the xenobiotic and 7-ethoxyresorufin caused EROD activity to fall at high xenobiotic concentrations. Competition for a limited number of Ah receptor sites depressed the EROD activity of a strong inducer such as 2,3,7,8-tetrachlorodibenzo-p-dioxin at high concentrations of a weak inducer. Application of the kinetic model to the example of a mixture of low concentrations of dibenzo-p-dioxins and much higher concentrations of polychlorinated biphenyls indicated that EROD assays often seriously underestimate the true potency of an environmental sample. Hence the EROD assay cannot be used for determining dioxin equivalent concentrations using the toxic equivalence factor approach.

Caspase-dependent cleavage of the hematopoietic specific adaptor protein Gads alters signalling from the T cell receptor.

Gads is a SH2 and SH3 domain-containing, hematopoietic-specific adaptor protein that functions in signalling from the T cell receptor. Gads acts by linking SLP-76, bound by the carboxy-terminal Gads SH3 domain, to tyrosine phosphorylated LAT which contains binding sites for the Gads SH2 domain. Gads is distinguished from Grb2 and the closely related Grap protein by the presence of a 120 amino acid unique region between the SH2 domain and the carboxy terminal SH3 domain. Here we demonstrate that the unique region of Gads contains a capase cleavage site. Induction of apoptosis in lymphocytes results in detectable Gads cleavage by 60 min. Gads cleavage is blocked in vivo by treating cells with a caspase 3 inhibitor. A putative caspase 3 cleavage site was identified within the unique region and mutation of this site prevented Gads cleavage in vitro, and in vivo. The Gads cleavage products retained the predicted binding specificity for SLP-76 and LAT. Expression of the Gads cleavage products in Jurkat T cells inhibited NFAT activation following TCR cross linking. These findings indicate that cleavage of Gads in vivo could function to alter signalling downstream of the T cell receptor by disrupting cross talk between SLP-76 and LAT.

Macrophage-like cell line (HS-P) from a rat histiocytic sarcoma.

With future exploration of macrophage properties in mind, we established a novel cell line (HS-P) from a transplantable histiocytic sarcoma, derived originally from a tumour in an aged F344 rat. HS-P was subjected to 70 serial passages, in which the mean doubling time was 15.7 h. The cells, which were round, oval or polygonal in shape, were arranged in a compact sheet. They reacted to varying degrees for lysosomal enzymes (acid phosphatase and non-specific esterase) and with the following antibodies: ED1/ED2 (rat macrophage/histiocyte-specific), OX6 (rat MHC class II-specific), lysozyme antibody and alpha1-antichymotrypsin antibody. Electron microscopically, HS-P cells showed lysosomes and prominent cell projections. These findings indicated that the cultured cells were macrophage-like. Syngeneic rats inoculated subcutaneously or intraperitoneally with HS-P cells invariably developed sarcomatous tumours consisting of monomorphic mononuclear cells, which exhibited cytochemical properties similar to those of cultured HS-P cells. Bioassay and reverse transcription-polymerase chain reaction methods revealed that tumour necrosis factor-alpha increased on addition of lipopolysaccharide (LPS), indicating that HS-P cells remained LPS-responsive. HS-P cells may prove to be a useful tool for in-vitro studies of macrophage function.

Cyclooxygenase expression in canine platelets and Madin-Darby canine kidney cells.

OBJECTIVE: To examine cyclooxygenase (COX) expression in canine platelets and Madin-Darby canine kidney (MDCK) cells in culture. SAMPLE POPULATION: Canine platelets and MDCK cells. PROCEDURE: Total RNA was recovered from isolated canine platelets and MDCK cells. Northern blot analysis and reverse transcription-polymerase chain reaction (RT-PCR), using complementary DNA probes and primers designed from the human COX sequences, were used to determine COX-1 and -2 (cyclooxygenase isoforms 1 and 2) messenger RNA (mRNA) expression. RESULTS: Following northern blot analysis, canine platelets were found to express only the 2.8-kb COX-1 transcript; COX-2 was not detected. Canine MDCK cells expressed the 4.5-kb COX-2 transcript, in addition to the 2.8-kb COX-1 transcript. A single DNA band of 270 base pairs was identified following gel electrophoresis of the product obtained from RT-PCR of mRNA from canine platelets. Sequencing revealed that this PCR product was 90% homologous to a portion of the human COX-1 gene (Genbank M59979). CONCLUSIONS AND CLINICAL RELEVANCE: Detection of COX-1 by RT-PCR of RNA obtained from canine platelets is a novel finding. The 90% homology of the PCR product with the human sequence suggests strong conservation between the canine and human COX-1 gene. Cloning and sequencing of the canine gene will be required to fully characterize homologous regions. Because of the importance of COX in the inflammatory process and as a potential target of currently available nonsteroidal anti-inflammatory drugs (NSAID), a better understanding of canine COX may improve our ability to use NSAID appropriately, achieve efficacy, and avoid potential adverse drug effects in dogs.

In vitro effects of nonsteroidal anti-inflammatory drugs on cyclooxygenase activity in dogs.

OBJECTIVE: To establish an in vitro assay and determine the differential suppressive activity of non steroidal anti-inflammatory drugs (NSAID) on cyclooxygenase (COX)-1 and COX-2 isoenzymes in dogs. PROCEDURE: COX activity was evaluated in the presence and absence of 4 NSAID (meloxicam, tolfenamic acid, carprofen, and ketoprofen), using a canine monocyte/macrophage cell line that constitutively expresses COX-1, but can be induced to express COX-2 when incubated with lipopolysaccharide. Inhibition of prostaglandin E2 TPGE2) synthesis by each NSAID was measured by enzyme immunoassay and attributed to specific COX-1 or COX-2 activity through assessment of COX messenger RNA expression by use of northern blot analysis and reverse transcription-polymerase chain reaction (RT-PCR). The COX selectivity of each drug was evaluated from dose-response curves by calculating a ratio (COX-1:COX-2) of inhibitory concentration values on the basis of concentrations that reduced PGE2 by 50% in each COX model. RESULTS: Meloxicam and tolfenamic acid preferentially inhibited COX-2, with meloxicam inhibiting COX-2 activity 12 times more effectively than COX-1 activity. Carprofen was only 1.75 times more selective for COX-2 than for COX-1, and ketoprofen was slightly more selective for COX-1. CONCLUSIONS: COX-1 and COX-2 were differentially sensitive to inhibition in vitro by NSAID. Meloxicam and tolfenamic acid were selective for COX-2. Effects of carprofen and ketoprofen approached equipotency against both isoenzymes. Selective COX-2 inhibitors are a new class of drugs with anti-inflammatory effects similar to conventional NSAID but with fewer adverse effects. Development of these agents for veterinary use would be facilitated by the convenience of using a canine cell line as a model system to screen COX-1 and COX-2 inhibitor activities in vitro.

Enhanced macrophage resistance to Pseudomonas exotoxin A is correlated with decreased expression of the low-density lipoprotein receptor-related protein.

Cellular intoxification by exotoxin A of Pseudomonas aeruginosa (PEA) begins when PEA binds to its cellular receptor, the low-density lipoprotein receptor-related protein (LRP). This receptor is particularly abundant on macrophages. We hypothesize here that inducible changes in cellular expression levels of the LRP represent an important mechanism by which macrophage susceptibility to PEA is regulated by the host. We have examined the effect of lipopolysaccharide (LPS) on LRP expression and PEA sensitivity in the macrophage-like cell line HS-P. Using a [(3)H]leucine incorporation assay to measure inhibition of protein synthesis, we have demonstrated that HS-P macrophages are highly sensitive to PEA and that PEA toxicity is decreased by the LRP antagonist receptor-associated protein. LPS pretreatment decreases HS-P PEA sensitivity in a time- and dose-dependent manner. The dose of toxin required to inhibit protein synthesis by 50% increased from 11.3 +/- 1.2 ng/ml in untreated cells to 25.7 +/- 2.0 ng/ml in cells treated with LPS. In pulse experiments, involving brief exposure to saturating concentrations of PEA, [(3)H]leucine incorporation was more than threefold higher in cells pretreated with LPS than in untreated macrophages. These changes in HS-P PEA sensitivity following LPS treatment were consistently associated with a fivefold decrease in HS-P LRP mRNA expression as measured by Northern blot analysis and a three-and-a-half-fold decrease in HS-P LRP-specific ligand internalization as determined by activated alpha(2)-macroglobulin internalization studies. These data demonstrate for the first time that modulation of LRP levels by extracellular signaling molecules can alter cellular PEA sensitivity.

The influence of hepatic venous oxygen saturation on the liver's synthetic response to metabolic stress.

Hepatic oxygen consumption (HVO2) and hepatic venous oxygen saturation (ShvO2) were assessed in the isolated perfused rat liver under conditions that mimic critical illness in an effort to assess their utility in predicting the functional status of the liver. Flow rates were adjusted over the physiologic range of oxygen transport as indicated by the hepatic venous O2 saturation range of 10%-75%. HVO2 was found to be transport (HDO2) dependent only when perfusate conditions contained an increased counterregulatory hormone (glucagon, epinephrine, dexamethasone) stimulus or a high lactate concentration. In the absence of a metabolic load, (substrate and hormone-free perfusate), HVO2 was transport independent even at an ShvO2 as low as 10%. Although transport dependency of HVO2 is frequently used to infer tissue ischemia, hepatic oxygen consumption was poorly correlated with synthetic function under all conditions. In contrast, hepatic albumin production was directly related to ShvO2 at all levels of HDO2 and under all perfusion conditions indicating that this metabolic process is particularly sensitive to reductions in oxygen availability, which is more reliably predicted by venous saturation measurements. However, glucose and urea synthesis were almost independent of ShvO2. These findings indicate that various hepatic processes are affected differentially by stress conditions and flow alterations that may exist during critical illness, and protein synthesis is particularly sensitive to oxygen deprivation. Additionally, hepatic venous oxygen saturation measurement, but not HVO2, serves as a useful surrogate marker for hepatic albumin production suggesting that regional venous oximetry may play an important role in the detection of hepatic functional impairment.

Expression of hepatocyte low-density lipoprotein receptor-related protein is post-transcriptionally regulated by extracellular matrix.

The low-density lipoprotein receptor-related protein (LRP) is a multifunctional member of the low-density lipoprotein receptor family that has been implicated in a variety of physiologic and pathologic processes. However, little is known about LRP regulation at the molecular level, and the factors that might mediate LRP have not yet been characterized. This is particularly true of hepatocytes, an important site of LRP expression. Hepatocyte gene expression is known to be dependent on extracellular matrix composition, although the effect of extracellular matrix on lipoprotein receptor expression has not yet been investigated. Also, the mechanisms by which the extracellular matrix affects hepatocyte gene expression are not well understood. In this study, we show that hepatocyte LRP expression decreases rapidly at the mRNA, protein, and functional levels on collagen type I, but remains high on an Engelbreth-Holm-Swarm sarcoma matrix-preparation, Matrigel. LRP function was assessed with ligand binding studies and a novel cytotoxicity assay, using Pseudomonas exotoxin A. Investigation of the mechanism of LRP down-regulation revealed a two-fold longer LRP mRNA half-life in hepatocytes cultured on Matrigel relative to collagen. Taken together, these studies reveal that LRP expression in primary hepatocytes is dependent on the extracellular matrix, and that matrix-dependent differences in hepatocyte LRP mRNA expression are primarily due to changes in mRNA stability, indicating for the first time that the expression of LRP is subject to post-transcriptional regulation.

Particle-mediated gene transfer with transforming growth factor-beta1 cDNAs enhances wound repair in rat skin.

Based on preliminary but variable results with direct DNA transfer into wounds, we evaluated in vivo gene transfer by particle-mediated DNA delivery to rat skin to determine whether overexpression of TGF-beta1 at the site of skin incisions would result in a significant improvement in repair. Optimization of the method with viral promoter-luciferase reporter constructs indicated that expression of luciferase activity persisted up to 5 d and was promoter, pressure, and site dependent (ventral > dorsal). Using cytomegalovirus (CMV)-driven human alpha1-antitrypsin, transgene expression was immunolocalized within keratinocytes of the stratum granulosum at 24 h. We measured tensile strength of skin incisions at 11-21 d in both normal and diabetic rats transfected with TGF-beta1 expression vectors at surgery. Native murine TGF-beta1 under an SV40 promoter produced positive effects, while wound strengthening was more pronounced in diabetic animals using a CMV-driven construct. Transfection of rat skin with constitutively active, mutant porcine TGF-beta1 under the control of the CMV and Moloney murine leukemia virus promoters significantly increased tensile strength up to 80% for 14-21 d after surgery. Transfection 24 h before surgery was more effective. Particle-mediated gene delivery can be used to deliver viral promoter-cytokine expression constructs into rat skin in a safe, efficient, and reproducible fashion. The extent of wound repair, as evidenced by enhanced tensile strength, can be markedly improved in tissues transfected with TGF-beta1 expression constructs.

Circulatory responses to weight lifting, walking, and stair climbing in older males.

OBJECTIVES: To compare the heart rate and intra-arterial blood pressure responses during weight lifting, horizontal and uphill walking, and stair climbing in older male subjects. DESIGN: We used intra-brachial artery catheterization to compare the arterial blood pressure (ABP) and heart rate (HR) responses during 10 repetitions (approximately 40 s) of single-arm curl (SAC) and single-arm overhead military press (SAMP) (70% of the one repetition maximum-1RM); 12 repetitions (approximately 50 s) of single- (SLP) and double-leg press (DLP) weight-lifting exercises (80% of 1RM); 10 minutes of horizontal treadmill walking (T10) at 2.5 mph holding a 20-pound weight in minutes 4 to 6 (T10) and 30 pounds in minutes 8 to 10 (T10); 4 minutes of treadmill walking (T4) at 3.0 mph up an 8% incline; and 12 flights (192 steps) of stair climbing (STR) at 60 to 65 steps/minute on a Stiarmaster 6000 ergometer (approximately 3 minutes). SETTING: McMaster University, Hamilton, Ontario, Canada. PARTICIPANTS: Seventeen healthy males aged (mean +/- SE) 64.4 +/- 0.6 years. MEASUREMENTS: Continuous intra-arterial measurements of systolic, diastolic, and mean arterial pressure and heart rate and rate-pressure product. RESULTS: The peak values of HR, ABP and rate-pressure product (HR.BPs/1000;(RPP,10(3))) were not systematically ordered among the various activities. The lowest peak values for all variables were recorded during the initial 4 minutes of horizontal treadmill walking. The STR and T4 walking exercises elicited higher HRs (151 +/- 3.2 and 121 +/- 3.4 bpm) than the weight lifting (range from 100 +/- 4.8 (SAC) to 113 +/- 3.8 bpm (SAMP)), but the converse was true for diastolic pressure (range from 128 +/- 6.3 (SAC) to 151 +/- 4.8 mm Hg (SAMP) versus 101 +/- 2.5 (T4) to 118 +/- 3.4 mm Hg (T10) and mean arterial pressure (range from 145 +/- 4.5 (SAC) to 158 +/- 4.8 mm Hg (SAMP) versus 129 +/- 3.4 in T4 to 148 +/- 3.8 (T10) and 157 +/- 4.1 mm Hg (STR)). The peak systolic pressure was greatest in STR (271 +/- 9.6 mm Hg) followed by SAMP (261 +/- 9.3 mmHg) and T10 (244 +/- 6.4 mm Hg) and was lowest in SAC (224 +/- 10.5 mm Hg) and T10 (220 +/- 5.7 mm Hg). The peak RPP descended in sequence from STR (41 +/- 1.8), SAMP (29.8 +/- 1.7), T4 (28.1 +/- 1.3), DLP (27.2 +/- 1.3), T10 (27.1 +/- 1.4), SLP (25.4 +/- 1.7), T10 (22.7 +/- 1.2) and SAC (22.0 +/- 2.2). CONCLUSION: We concluded that older adults who engage in weight lifting with heavy submaximal loads are exposed to no more peak circulatory stress than that created during a few minutes of inclined walking. Moreover, climbing only three to four flights of stairs at a moderate pace (approximately 50-70 s) elicits peak circulatory demands similar to, but at a much more rapid rate of adjustment than, 10 minutes of horizontal walking at 2.5 mph intermittently carrying a 30-pound weight or 4 minutes of walking up a moderately steep slope.

Surgical management of prolapse of the anterior vaginal segment: an analysis of support defects, operative morbidity, and anatomic outcome.

OBJECTIVES: The objectives of this study were to describe a group of women with prolapse of the anterior vaginal segment associated with bilateral paravaginal defects, to report the morbidity associated with the operative repair, and to analyze the results of preoperative and postoperative pelvic support defects in five vaginal sites. STUDY DESIGN: Between June 1, 1988, and Nov. 3, 1993, 62 consecutive women with prolapse of the anterior vaginal segment associated with bilateral periurethral and perivesicle support defects and other coexisting pelvic support defects were treated by paravaginal repair done via the vagina and total pelvic reconstruction. Site-specific analysis of support for the urethra, bladder, cervix or cuff, cul-de-sac, and rectum was performed preoperatively, 6 weeks postoperatively, and longitudinally to assess the anatomic outcome of surgery. Perioperative morbidity was defined as hemorrhage requiring homologous blood transfusion, pelvic nerve injury, deep venous thrombosis, visceral injury, or infection. RESULTS: One hundred percent of the study patients had preoperative evidence of bilateral paravaginal defects, and 87% had a prolapse of the anterior segment that was halfway to completely outside the hymen. Seven patients experienced perioperative morbidity none of which was unique to this procedure. Fifty-six patients have been followed up a mean of 1.6 years postoperatively. In four, anterior segment defects have developed to or through the hymen, although none is as large as the preoperative defect and none has required further surgery to date. In one patient a postoperative defect developed in the cul-de-sac extending to the hymen; she has had the defect repaired and has been followed up 1.7 years with no support defects. CONCLUSION: Paravaginal repair performed transvaginally is a safe, effective method of management of prolapse of the anterior vagina associated with paravaginal defects. Coexisting support defects that require specific identification and repair can also be managed vaginally.