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M K Smith

Publications and source records attributed to M K Smith.

At least 55 records · Page 3Linked to original sources
PubMed1993

The cost of ethics legislation: a look at the Patient Self-Determination Act.

The Patient Self-Determination Act (PSDA) requires hospitals to ask patients upon admission whether they have an advance directive. Although the PSDA has received extensive criticism, little attention has been paid to the cost of the law, either during its legislative course or following its implementation. Nonetheless, several tangible and intangible costs are associated with the PSDA. Such costs may be incurred by different parties. This paper examines the costs and benefits of the PSDA and illustrates the extent of some of its tangible costs. The incremental start-up cost for one institution's response to the PSDA is estimated to be $49,304 ($1.31 per admission) and the total implementation cost of the program to be $114,528. In addition, the national incremental start-up cost for hospitals to implement the PSDA is estimated to be between $43,625,114 and $101,569,922. Finally, the potential implications of the PSDA for future governmental health care ethics regulation are discussed.

Advance Directives↗
PubMed1992

Functional determinants in the autoinhibitory domain of calcium/calmodulin-dependent protein kinase II. Role of His282 and multiple basic residues.

Important determinants in the autoinhibitory domain of calcium/calmodulin-dependent protein kinase II (CaMK-II), corresponding to residues 281-302 of the kinase alpha-subunit sequence, were identified. Replacement of Thr286 with Ala (CaMK-(281-302 Ala286)) had no effect on either the potency (IC50 = 2 MicroM) or inhibitory mechanism (competitive with ATP) using the catalytic fragment of CaMK-II. Single replacement of charged residues in CaMK-(281-302, Ala286) identified His282, Arg283, Lys291, Arg297, and Lys298 as important determinants (greater than 10-fold increase in IC50) for potent inhibition of CaMK-II. Glu285, Asp288, Lys291, Arg296, and Lys300 were not as essential (less than 4-fold change in IC50) for potent CaMK-II inhibition. Replacement of either Arg283, Lys291, or Arg297, and Lys298 with Ala did not alter the ATP-competitive mechanism of inhibition although the Ki values increased 16-530-fold. However, replacement of His282 with Ala decreased the IC50 by 20-fold and altered the mechanism of inhibition to noncompetitive with respect to ATP. The non-protonated form of His282 was functionally active since decreasing the pH from 7.5 to 5.5 increased the IC50 of CaMK-(281-302, Ala286) almost 20-fold. Histidine protonation also appeared to disrupt the autoinhibitory domain of intact forms of CaMK-II since preincubation of non-proteolyzed rat brain CaMK-II with calcium/calmodulin (in the absence of ATP) at pH 5.5 generated up to 16% calcium-independent activity when assayed at pH 5.5. Similarly, the level of calcium-independent activity of a baculovirus-expressed Asp286 mutant CaMK-II ((D286)mCaMK alpha) increased to almost 80% calcium independence when assayed at pH 5.5 compared to only 20% when assayed at pH 7.5. The levels of calcium-independent activity of both the (D286)mCaMK alpha (at pH 5.5 and 7.5) and the rat brain CaMK-II (at pH 5.5) were sensitive to the concentrations of both ATP and peptide substrate (syntide-2) in the assays. These data suggest that the basic residues Arg283, Lys291, Arg297, and Lys298 are important for potent inhibition of CaMK-II and that the non-protonated form of His282 may play a unique role in the ATP-directed mechanism of inhibition by the CaMK-II autoinhibitory domain.

Amino Acid Sequence↗
PubMed1992

Developmental toxicity of dichloroacetate in the rat.

Dichloroacetic acid (DCA) is a principal by-product of the chlorine disinfection of water containing humic and fulvic acids, and is also a drug of interest in the therapeutic management of metabolic disorders. The developmental effects of DCA were evaluated in the pregnant Long-Evans rat. In two separate studies, animals were dosed by oral intubation on gestation days 6-15 (plug = 0) with 0, 900, 1,400, 1,900 or 2,400 mg/kg/day and 0, 14, 140, or 400 mg/kg/day. The vehicle control was distilled water. Maternal observations included clinical signs, weight change, and gross evaluation of organ weights and uterine contents at necropsy (day 20). Corpora lutea were counted and uteri stained for implantation sites. Live fetuses were examined for external, skeletal, and soft tissue malformations. Seven dams died during treatment (1,400 mg 1/19, 1,900 mg 2/19, 2,400 mg 4/21), and maternal weight gain was reduced at all except the lowest treatment levels. Liver, spleen, and kidney weights increased in a dose-related manner. The mean percentage of resorbed implants per litter was significantly elevated at greater than or equal to 900 mg/kg/day. Live fetuses showed dose-dependent reductions in weight and length at doses above 140 mg/kg. Statistically significant frequencies of soft tissue malformations ranged from 2.6% (140 mg/kg) to 73% (2,400 mg/kg). These were principally in the cardiovascular system and predominantly comprised defects between the ascending aorta and the right ventricle. Skeletal malformations were not observed in significant numbers in any dose group.(ABSTRACT TRUNCATED AT 250 WORDS)

Abnormalities, Drug-Induced↗
PubMed1992

Cardiopathic effects of dichloroacetate in the fetal Long-Evans rat.

Dichloroacetic acid (DCA) is a by-product of the chlorine disinfection of water and may occur in treated water at levels exceeding 100 micrograms/L. Previous studies revealed teratogenic effects, particularly heart malformations, at high doses (900-2,400 mg/kg given on days 6-15 of pregnancy). In a series of three studies, groups of 7-10 Long-Evans rats were dosed with 1,900 mg/kg of DCA on days 6-8, 9-11, or 12-15; with 2,400 mg/kg on days 10, 11, 12, or 13; and with 3,500 mg/kg on days 9, 10, 11, 12, or 13, in an attempt to determine the most sensitive period and further characterize the heart defect. In a fourth study, six dams were treated with 1,900 mg/kg of DCA days 6-15 of pregnancy, and 56 fetuses were harvested for light microscopy of the heart. Eight control fetuses from four litters were also examined. No heart malformations were seen in the groups treated with 1,900 mg/kg DCA days 6-8 but were present in the group treated on days 9-11 and 12-15, with the higher incidence occurring on days 12-15. Single doses of 2,400 mg/kg DCA given on days 10, 11, 12, or 13 resulted in a much lower incidence of cardiac malformations, which occurred only on days 10 and 12. The high dose of DCA (3,500 mg/kg) did not increase the incidence of heart defects but showed that dosing on day 9 as well as on days 10 and 12 would produce the defect. The defects seen were characterized as high interventricular septal defects (H-IVSD). Light microscopy showed that the defect was caudal to the semilunar valves, with the anterior right wall of the aorta communicating with the right ventricle. Another aspect of the defect is at the level of the semilunar valves, with the right cusp or sinus of Valsalva in communication with the right ventricle. The defects are discussed more fully and methods for further study suggested.

Animals↗
PubMed1992

Adverse male reproductive effects following subchronic exposure of rats to sodium dichloroacetate.

Dichloroacetate (DCA) activates the pyruvate dehydrogenase complex enhancing carbohydrate and lactate utilization in animals. As a result it is used clinically in the treatment of acute lactic acidosis and has therapeutic potential in the treatment of stroke. Adverse effects of chronic DCA treatment include polyneuropathy and testicular degeneration. Since DCA is a principal product of the aqueous chlorination of fulvic acids concern has arisen regarding the agent's impact on environmental health. We treated male Long-Evans rats with 0, 31.25, 62.5, or 125 mg DCA/kg/day by oral gavage for 10 weeks. Compared to controls, preputial gland and epididymis weights were reduced at 31.25 mg/kg, body and liver weights at 62.5 mg/kg, and accessory organ weights at 125 mg/kg. Epididymal sperm counts were reduced and sperm morphology was impacted at the 62.5 and 125 mg/kg doses levels. Histologic examination of the testis and epididymis revealed inhibited spermiation in testes at the 125 mg/kg dose level. Computer-assisted sperm motion analysis revealed reductions in percentage motile sperm, curvilinear and straight-line velocity, linearity, and amplitude of lateral head displacement at both the 62.5 and the 125 mg/kg dose levels. In the assessment of fertility after an overnight mating, the number of viable implants on Day 14 of gestation was decreased only in the highest dose group. These studies demonstrate adverse effects of NaDCA treatment on the rat male reproductive system, primarily on the accessory organs and sperm within them at lower doses (31.25 and 62.5 mg/kg), and on the testis at the highest dose (125 mg/kg).

Animals↗
PubMed1992

Effects of three male reproductive toxicants on rat cauda epididymal sperm motion.

The sensitivity of the CellSoft computer-assisted sperm analysis (CASA) system to detect changes in rat sperm motion was evaluated. CASA motion endpoints were measured in cauda epididymal sperm from Long-Evans rats treated with each of three known male reproductive toxicants reported to affect the epididymis and epididymal sperm motility: alpha-chlorohydrin, ornidazole, and trimethylphosphate. Significant changes in endpoints describing sperm swimming vigor (curvilinear velocity and straight-line velocity) and pattern (linearity and amplitude of lateral head displacement) were observed for rats dosed with each agent when evaluations included mean values and other statistical parameters (i.e., percentiles and distributional shape). alpha-Chlorohydrin (ACH) treatment (10 mg/kg/day; 8 days) resulted in reductions in the mean percentage of motile sperm, curvilinear velocity (VCL), straight-line velocity (VSL), lateral head displacement (ALH), and linearity (LIN). Treatment with ornidazole (ONZ) (200 mg/kg/day/14 days) reduced the percentage of motile sperm. Mean VCL, VSL, and ALH were reduced by 400 mg ONZ/kg/day treatment. Trimethylphosphate (TMP) treatment led to (a) a reduction in the 75th and 90th percentiles for ALH (100 mg TMP/kg/day; 5 days) (P < or = 0.04), (b) a reduction in VCL, VSL, and ALH (250 mg TMP/kg/day), (c) a reduction in the percentage of motile cells and in the 10th and 25th percentiles for VSL (600 mg TMP/kg/day), and (d) increases in the 90th percentile for VSL, in the mean, 75th, and 90th percentiles for VCL, and in the 75th and 90th percentiles for ALH (600 mg TMP/kg/day). The general utility of these analytic approaches in reproductive toxicology studies was demonstrated in the observations of effects at or below dose levels previously reported.

Administration, Oral↗
PubMed1991

Sources of variation in the computer-assisted motion analysis of rat epididymal sperm.

Random and nonrandom factors associated with sample preparation and the automated analysis (CellSoft) of rat cauda epididymal sperm motion were studied. Random factors included inherent system variation at both the individual cell level and at the multiple cell level. Repeated analyses of identical tracks across grey level revealed a statistical interaction between grey settings and curvilinear velocity. However, in multiple track analyses, grey level was seen to be a factor only at higher settings. Nonrandom factors included time after sample preparation, dilution medium, and sample preparation procedures. Using a nicked preparation of the entire cauda epididymis from Long-Evans rats, the effects of time were studied on sperm suspended in 1) phosphate-buffered saline + 10 mg BSA/mL, 2) TEST yolk buffer, and 3) Medium 199. In PBS/BSA, the percent motile sperm estimate decreased (50% to 30%) over an hour, while the curvilinear velocity increased (127 to 142 microns/sec). Both sperm motion parameters were maintained in the TEST yolk buffer and in the Medium 199, although at lower values for the latter. Evaluation of the relative contribution of several factors, nested within sample, to the overall variance of three separate motion endpoints revealed that there was a large variation from field to field, negligible variation between overall CellSoft analyses of 200 cells or more, low variation at the preparation aliquot level, and moderate variation at the animal level. In planning experiments to test for effects on sperm motion endpoints, consideration of the relative contribution of the individual study factors to the overall variance of the parameter estimates will result in more sensitive experimental designs.

Animals↗
PubMed1991

Reproductive effects in Long-Evans rats exposed to chlorine dioxide.

Long-Evans rats, 4-6 weeks of age, were dosed with 0.0, 2.5, 5.0, or 10.0 ml/kg chlorine dioxide (ClO2) in deionized water for up to 73 days. Males were exposed for 56 days and females for 14 days prior to breeding, and throughout the 10-day breeding period. Males were killed and evaluated for sperm parameters and reproductive tract histopathology following the breeding period. Females continued to be dosed throughout gestation and lactation until weaning on lactation day 21, when both dams and selected pups were necropsied. Neither clinical signs of toxicity nor adverse effects on any reproductive parameter examined were observed in the parental animals. Litter size, pup viability, and pup weight were unaltered by chlorine dioxide exposure. F0 reproductive tract organ weights and F1 organ weights for testis, epididymis, uterus, and ovaries were not different between groups, but vaginal weight was significantly decreased (P less than 0.03) for female weanlings in the high dose (10.0 mg/kg) group relative to controls. There were no changes in thyroid hormone parameters that appeared to be attributable to chlorine dioxide treatment.

Animals↗
PubMed1990

Specificities of autoinhibitory domain peptides for four protein kinases. Implications for intact cell studies of protein kinase function.

Synthetic peptides corresponding to the autoinhibitory domains of calcium/calmodulin-dependent protein kinase II (CaMK-(281-309)), smooth muscle myosin light chain kinase (MLCK-(480-501)), and protein kinase C (PKC-(19-36)) as well as a peptide derived from the heat-stable inhibitor of cAMP-dependent protein kinase (PKI-tide) were tested for their inhibitory specificities. The inhibitory potencies of the four peptides were determined for each of the four protein kinases using both peptide substrates (at approximate Km concentrations) and protein substrates (at concentrations less than Km). In agreement with previous studies PKI-tide was a specific and potent inhibitor of only cAMP kinase, and none of the other inhibitory peptides gave significant inhibition of cAMP kinase at concentrations of less than 100 microM. With synthetic peptide substrates, PKC-(19-36) strongly inhibited native PKC (IC50 less than 1 microM) but also significantly inhibited autophosphorylated CaMK-II (IC50 = 30 microM) and proteolytically activated MLCK (IC50 = 35 microM). MLCK-(480-501) potently inhibited MLCK (IC50 = 0.25 microM) and also strongly inhibited both PKC and CaMK-II (IC50 = 1.4 and 1.7 microM, respectively). CaMK-(281-309) inhibited autophosphorylated CaMK-II, PKC, and proteolyzed MLCK almost equally (IC50 = 10, 38, and 48 microM, respectively). Qualitatively similar results were obtained with protein substrates. These studies validate the use of PKI-tide as a specific inhibitor of cAMP kinase in intact cell studies and suggest that PKC-(19-36) can also be used but only within a narrow concentration range. However, the autoinhibitory domain peptides from MLCK and CaMK-II are not sufficiently specific to be used in similar investigations.

Amino Acid Sequence↗
PubMed1990

Effects of chlorine dioxide on the developing rat brain.

Male and female Long-Evans rat pups, exposed to an oral dose of 14 mg chlorine dioxide (CIO2)/kg/d (postnatal d 1-20), were examined for effects on brain development and for changes in thyroid activity. Body weight reductions were observed on postnatal (pn) d 11, 21, and 35. Forebrain weight and protein content were decreased on pnd 21 and 35, as were the DNA content on d 35 and the number of dendritic spines on cerebral cortical pyramidal cells, a marker for synapse formation. Otherwise, cell proliferation in the forebrain, cerebellum, and olfactory bulbs was normal, as were migration and aggregation of neuronal cells in three areas of the cerebral cortex. Histopathology of the forebrain, cerebellum, and brainstem showed no gross lesions, loss of myelin, or change in the cells staining positive for Nissl substance. Serum T3 and T4 levels, as well as hepatic mitochondrial alpha-glycerophosphate dehydrogenase activity, were unchanged by CIO2 treatment. The results indicated that CIO2 may have central neurotoxic potential. No underlying antithyroid activity was evident.

Animals↗
PubMed1989

Regulatory domain of calcium/calmodulin-dependent protein kinase II. Mechanism of inhibition and regulation by phosphorylation.

Regulatory mechanisms of rat brain Ca2+/calmodulin-dependent protein kinase II (CaM-kinase II) were probed using a synthetic peptide (CaMK-(281-309] corresponding to residues 281-309 (alpha-subunit) which contained the calmodulin (CaM)-binding and inhibitory domains and also the initial autophosphorylation site (Thr286). Kinetic analyses indicated that inhibition of a completely Ca2+/CaM-independent form of CaM-kinase II by CaMK-(281-309) was noncompetitive with respect to peptide substrate (syntide-2) but was competitive with respect to ATP. Interaction of CaMK-(281-309) with the ATP-binding site was independently confirmed since inactivation of proteolyzed CaM-kinase II by phenylglyoxal (t1/2 = 7 min) was blocked by ATP analog plus Mg2+ or by CaMK-(281-309). In the presence of Ca2+/CaM, CaMK-(281-309) no longer protected against phenylglyoxal inactivation, consistent with our previous observations (Colbran, R.J., Fong, Y.-L., Schworer, C.M., and Soderling, T.R. (1988) J. Biol. Chem. 263, 18145-18151) that binding of Ca2+/CaM to CaMK-(281-309) 1) blocks its inhibitory property, and 2) enhances its phosphorylation at Thr 286. The present study also showed that phosphorylation of CaMK-(281-309) decreased its inhibitory potency at least 10-fold without affecting its Ca2+/CaM-binding ability. Thus, CaM-kinase II is inactive in the absence of Ca2+/CaM because an inhibitory domain within residues 281-309 interacts with the catalytic domain and blocks ATP binding. Autophosphorylation of Thr286 results in a Ca2+/CaM-independent form of the kinase by disrupting the inhibitory interaction with the catalytic domain.

Adenosine Triphosphate↗
PubMed1989

Teratogenic activity of trichloroacetic acid in the rat.

Trichloroacetic acid (TCA) is a by-product of the chlorine disinfection of water containing natural organic material. It is detectable in finished drinking water at levels comparable to the trihalomethanes (30-160 micrograms/L). TCA is also formed in vivo after ingestion of hypochlorite and has been identified as a major metabolite of chlorinated hydrocarbons such as trichloroethylene. The developmental effects of TCA were evaluated in the pregnant Long-Evans rat. Animals were dosed by oral intubation on gestation days 6-15 (plug = 0) with 0, 330, 800, 1,200, or 1,800 mg/kg/day. The vehicle control was distilled water. Maternal observations included clinical signs, weight change, and gross evaluation of organ weights and uterine contents at necropsy (day 20). Live fetuses were examined for external, skeletal, and soft tissue malformation. There were no maternal deaths associated with toxicity prior to sacrifice. Weight gain during treatment was reduced at 800, 1,200, and 1,800 mg/kg. Spleen and kidney weights were increased in a dose-related manner. The mean percent of resorbed implants per litter was 34, 62, and 90 at 800, 1,200, and 1,800 mg/kg, respectively. Live fetuses showed dose-dependent reductions in weight and length. The mean frequency of soft tissue malformations ranged from 9% at the low dose to 97% at the high dose. These were principally in the cardiovascular system (interventricular septal defect, levocardia). Skeletal malformations were found only at 1,200 and 1,800 mg/kg and were mainly in the orbit. Based on these observations TCA was considered to be developmentally toxic in the pregnant rat at doses of 330 mg/kg and above.

Abnormalities, Drug-Induced↗
PubMed1989

Developmental toxicity of dichloroacetonitrile: a by-product of drinking water disinfection.

Dichloroacetonitrile (DCAN), a by-product of drinking water disinfection formed by reaction of chlorine with background organic materials, was evaluated for its developmental effects in pregnant Long-Evans rats. Animals were dosed by oral intubation on Gestation Days 6-18 (plug = 0) with 0, 5, 15, 25, or 45 mg/kg/day. Tricaprylin was used as a vehicle. The highest dose tested (45 mg/kg) was lethal in 9% of the dams and caused resorption of the entire litter in 60% of the survivors. Embryolethality averaged 6% per litter at the low dose and 80% at the high dose and was statistically significant at 25 and 45 mg/kg/day. The incidence of soft tissue malformations was dose related and was statistically significant at doses toxic to the dam (45 mg/kg). These anomalies were principally in the cardiovascular (interventricular septal defect, levocardia, and abnormalities of the major vessels) and urogenital (hydronephrosis, rudimentary bladder and kidney, fused ureters, pelvic hernia, cryptorchidism) systems. The frequency of skeletal malformations (fused and cervical ribs) was also dose related and significantly increased at 45 mg/kg. The no-observed-adverse-effect dose for toxicity in pregnant Long-Evans rats was established by statistical analysis to be 15 mg/kg/day.

Acetates↗
PubMed1989

Effects of epichlorohydrin on male and female reproduction in Long-Evans rats.

Male and female Long-Evans rats were treated with epichlorohydrin (ECH) by oral gavage (males: 12.5, 25, and 50 mg/kg/day; females: 25, 50, and 100 mg/kg/day) for 21 and 14 days, respectively, prior to mating trials with untreated animals. Treated females were further dosed until delivery. Fertility was assayed in the high-dose males only and was found to be totally impaired. No measured parameters of female reproduction were changed relative to controls. Treated males showed normal copulatory behavior. Sperm morphology and percentage motile sperm were not statistically different from control values in both ejaculated and cauda epididymal samples from ECH-treated animals. The number of sperm in ejaculates was normal while cauda epididymal sperm count was slightly decreased in males at the 50 mg ECH/kg dose level. Mean curvilinear velocity, straight-line velocity, and amplitude of lateral head displacement of cauda epididymal sperm were significantly reduced by ECH at 12.5 mg/kg/day and above. Sperm track linearity was also reduced, but only at 50 mg/kg/day. Beat/cross frequency of sperm was significantly increased at 12.5 mg/kg/day and above. All of the above sperm motion parameters showed dose-dependent trends. These effects are consistent with the spermatozoal metabolic lesions reported for alpha-chlorohydrin, a metabolite of ECH.

Animals↗
PubMed1989

Factors associated with reduced fertility and implantation rates in females mated to acrylamide-treated rats.

A series of studies was conducted to examine the role of copulatory dysfunction, spermatotoxicity, and/or impaired fertilization in the reduced rates of fertility and implantation observed in females mated to acrylamide-treated male rats. In initial experiments, males were gavaged with 0, 5, 15, 30, 45, or 60 mg/kg acrylamide (ACR) for 5 days and then mated serially to naive females. ACR treatment reduced fertility and increased pre- and post-implantation loss, primarily over the first 3 weeks post-treatment. The effects at Week 1 appeared to result from an interference in sperm transport as demonstrated by the absence of sperm in the uteri of females following a single ejaculation by ACR-treated male rats. The effect however was transient, with recovery of fertility in all but the 60 mg/kg group by Week 2. Attempts to explain the reduced rate of implantation concentrated on characterizing changes in measures of ejaculated sperm count and various motility parameters and evaluating sperm fertilizing ability. Males were again dosed acutely with ACR (p.o.). ACR produced statistically significant, but modest, alterations in sperm motility at Week 3. More prominent was the marked decrease in the number of fertilized ova recovered from females mated to ACR-treated males at Week 3. These data suggest that events critical to the fertilizing ability of the sperm appear to play a major role in the reduced reproductive competence associated with ACR treatment in male rats.

Acrylamides↗
PubMed1988

Molecular evolution of the mouse proline-rich protein multigene family. Insertion of a long interspersed repeated DNA element.

Proline-rich proteins (PRPs) in the salivary glands of mice, rats, and hamsters are encoded by tissue-specific inducible multigene families. Mouse PRP genes are located on chromosome 8, and transcription is dramatically induced (about 70-fold) by isoproterenol treatment. Clones containing two nonallelic PRP genes (MP2 and M14) were isolated from cosmid and phage libraries of CD-1 mouse genomic DNA. The cloned regions comprise a contiguous block of 77 kilobase pairs of the mouse genome. Restriction mapping established the physical lineage of PRP genes MP2 and M14, and they are tandemly arrayed. The DNA sequence analysis presented in this report suggests that genes M14 and MP2 (Ann, D. K., and Carlson, D. M. (1985) J. Biol. Chem. 260, 15863-15872) arose via a gene duplication of a common ancestor. Two major differences between M14 and MP2 were observed. PRP gene MP2 has 13 tandemly arrayed 42-nucleotide repeats in exon II, whereas M14 has 17 repeats, and PRP gene M14 has an insertion by transposition of a 2-kilobase pair member of the long interspersed repeated DNA (LINE) family (LIMd) into intron I. The evolution of this PRP multigene family has been dominated by intra-exonic amplification of repeating nucleotide units coding for these and other proline-rich repeated peptides and by gene duplication. The LIMd element gives rise to heterogenous EcoRI, BamHI, and HindIII restriction enzyme patterns, and this insertion is also present in BALB/c, C57BL/6J, and DBA/2J mice.

Amino Acid Sequence↗