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Biomedical subjects

D L Wood

Publications and source records attributed to D L Wood.

At least 19 recordsLinked to original sources
PubMed1992

Left ventricular dysfunction due to atrial fibrillation in patients initially believed to have idiopathic dilated cardiomyopathy.

Ten patients aged 22 to 80 years (median 57) with severe left ventricular (LV) dysfunction and atrial fibrillation (AF) with rapid ventricular response were evaluated after therapy. Because most patients were unaware of their arrhythmia, duration was usually unknown. All patients had heart failure symptoms; 9 presented with New York Heart Association class III or IV disability, and 1 with class II disability. Initial LV ejection fraction ranged from 12 to 30% (median 25). No patient had symptomatic coronary artery disease (4 underwent angiography). Myocarditis and infiltrative processes were excluded by biopsy in 5 patients. All patients were considered initially to have idiopathic dilated cardiomyopathy with secondary AF. Ventricular rate was controlled in all patients, with sinus rhythm restored in 5. At follow-up (median 30 months, range 3 to 56), all patients were asymptomatic. LV ejection fraction after treatment ranged from 40 to 64% (median 52). It is concluded that in some patients initially considered to have idiopathic dilated cardiomyopathy, AF with rapid ventricular response may be the primary cause rather than the consequence of severe LV dysfunction. LV dysfunction may be completely reversible with ventricular rate control.

Adult↗
PubMed1992

Characterization of an intron 12 splice donor mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene.

Cystic fibrosis, the most common lethal genetic disease in the white population, is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Analysis of DNA from a pancreatic insufficient patient by chemical mismatch cleavage and subsequent DNA sequencing led to the identification of a potential splice mutation in the CFTR gene. A transition of the invariant guanosine to adenosine (1898 + 1G > A) was found at the splice donor site of intron 12. To determine the effect of this mutation on the patient's CFTR transcripts, RNA from the nasal epithelium was reverse transcribed and amplified by the polymerase chain reaction (RT-PCR). Direct sequencing of the PCR products revealed that the transcript from the chromosome with the 1898 + 1G > A mutation had skipped exon 12 entirely, resulting in a joining of exons 11 and 13. Deletion of exon 12 results in the removal of a highly conserved region which encodes the Walker B consensus sequence of the first nucleotide-binding fold of CFTR.

Adult↗
PubMed1992

Human mammary gland function at the onset of lactation: medium-chain fatty acid synthesis.

The onset of medium-chain fatty acid synthesis in the human mammary gland was investigated. Colostrum and serum were collected from 31 healthy women and the fatty acid composition of total lipid was analyzed by gas-liquid chromatography. Although colostrum/serum ratios for most fatty acids range from 0.7-2.4, very low levels of 10:0 and 12:0 were present in serum lipids as compared to much higher concentrations of these fatty acids in colostrum lipids (colostrum/serum ratio 16.23 and 17.11 for 10:0 and 12:0, respectively). We have previously found that medium-chain fatty acid levels are very low in prepartum mammary secretions (6-10 wk before term delivery) but are higher and similar in colostrum of women who deliver preterm (3-14 wk) or at full term. The data indicate that parturition, irrespective of length of pregnancy, is the trigger for medium-chain fatty acid synthesis in the human mammary gland.

Breast↗
PubMed1992

Incorporation of [14C] arachidonic acid into ovine conceptus and endometrial lipids.

The purpose of this study was to quantitate conceptus and endometrial incorporation of [14C]arachidonic acid (AA) into individual neutral and polar lipids. Endometrium and conceptuses from pregnant ewes and endometrium from nonbred ewes were collected 14 and 16 d after onset of estrus (d 0). Tissues were incubated for 8 h at 37 degrees C in medium containing 1 microCi of [14C]AA. Thin-layer chromatographic procedures were used to separate 12 lipids. Radioactivity was measured in each lipid, and the amount (ng) of [14C]AA incorporated into each lipid was calculated. Conceptuses and endometrium incorporated more [14C]AA into triacylglycerols than into any other lipid. Day and tissue type affected differentially (i.e., day X tissue interaction) the incorporation of [14C]AA into several lipids; d-14 conceptuses incorporated [14C]AA more actively than did any other day-tissue combination. Results indicate that triacylglycerols may be an important reservoir for conceptus and endometrial AA. The remarkable ability of d-14 conceptuses to incorporate [14C]AA into various lipids may be important for their accelerated elongation and active prostaglandin synthetic system.

Animals↗
PubMed1992

Out-of-hospital pleomorphic ventricular tachycardia and resuscitation: association with acute myocardial ischemia and infarction.

Pleomorphic ventricular tachycardia is characterized by QRS complexes with repeated variation in polarity, amplitude, and regularity. When associated with prolongation of the QT interval, the term torsades de pointes is used to describe the arrhythmia. It usually is seen clinically in association with class IA antiarrhythmic drugs such as quinidine and procainamide, bradycardia, hypokalemia, and, much less often, other drugs and electrolyte disorders as well as a result of congenital and neurogenic causes. It also may accompany acute myocardial infarction or ischemia. We describe four patients in whom pleomorphic ventricular tachycardia was observed as the presenting rhythm or during the course of resuscitation in out-of-hospital cardiac arrest. In all four patients, acute myocardial ischemia appeared to be the provocative mechanism. Therapeutic implications include an awareness of the unusual behavior of this arrhythmia, especially its propensity to terminate spontaneously. Such awareness may prevent the delivery of unnecessary defibrillatory shocks.

Acute Disease↗
PubMed1992

Milk and blood fatty acid composition during two lactations in the same woman.

Fatty acid composition of colostrum, milk, and serum was studied during two consecutive lactations in the same woman. There were marked differences between milk and serum: medium chain fatty acids (C6:0-C14:0) were higher in milk (8.36-21.37%) than in serum (1.59-9.6%) throughout lactation. The high milk-serum ratio of medium chain fatty acids (up to 28.4, 30.2, and 6.2 for 10:0, 12:0, and 14:0, respectively) indicates synthesis in the mammary gland. Long-chain polyunsaturated fatty acids (C20:1-C22:6) of the n - 3 and n - 6 series were higher in serum (6.76-12.53%) than in milk (1.57-4.42%). With the exception of colostrum, the fatty acid composition of milk and serum changed little during lactation and was similar in two consecutive lactations in the same woman. Comparison of milk and serum fatty acids provides a noninvasive approach for the assessment of the synthetic activity of the human mammary gland.

Adult↗
PubMed1992

The ability of bovine mammary tissue to synthesize lipids for 96 h when cocultured with liver and adipose tissue.

Explants of bovine mammary, liver, and adipose tissues were cocultured in the same well for 24, 48, 72 or 96 h and their ability to synthesize lipids was measured by the incorporation of [14C]acetate into triglycerides, free fatty acids, and phospholipids. The model was developed to study the effect of bovine somatotropin on lipid synthesis in mammary tissue, because somatotropin will not affect mammary tissue unless liver tissue is present. Somatotropin reduced incorporation by mammary tissue relative to the control. However, the rate of incorporation remained constant through 96 h with somatotropin, but steadily decreased in control mammary tissue. Phospholipid release into the media increased dramatically from 2% of that synthesized during the first 24 h to 218% of that synthesized from 72 to 96 h. The high release of phospholipids after 24 h suggests that cellular breakdown was occurring. A 24-h incubation is recommended to study lipid synthesis with this system.

Adipose Tissue↗
PubMed1992

Changes in the lipid composition of the secretions of the bovine mammary gland during the dry period.

To study initiation of milk fat synthesis, lipid composition of mammary secretions at -60, -40, and -10 d prepartum was studied in lactating and nonlactating Holstein cows. Eleven cows were dried off, and 13 cows were milked twice per day throughout the normal dry period. Total neutral lipid was similar in late lactation milk (-60 d) from lactating cows, 2.1 g/dl, and in milk from the dry group, 2.2 g/dl. Neutral lipids decreased to 1.3 and .9 g/dl in quarters from dry cows at -40 and -10 d prepartum. In secretions from dry quarters, triglycerides were 97% of total lipids at -60 d and decreased to 85 and 91% at -40 and -10 d, respectively. Conversely, FFA and monoglycerides increased during the dry period. Lipids associated with fat globule membrane components increased during the dry period. These increases were 10 times for cholesterol, 20 times for cholesteryl esters, and twice for phospholipids. In general, the content of fat globule core lipids (triglycerides) exhibited a pattern opposite that of membrane lipids (cholesterol, cholesteryl esters, phospholipids) during the prepartum period. Proportions of core lipids tended to decrease, whereas proportions of membrane lipids increased in prepartum mammary secretions. Lipid composition of prepartum secretions may be influenced by blood lipids, somatic cells, and alterations in mammary lipid synthesis.

Animals↗
PubMed1992

Effect of clinical and subclinical mastitis on lipid composition of teat canal keratin.

Two experiments were conducted to investigate lipid composition of teat canal keratin when different conditions of bacterial colonization and quarter inflammation were present. In Experiment 1, 11 multiparous cows with subclinical mastitis (bacteria present but no visible inflammation) in at least one quarter were selected for study. Quarters that were sampled and found negative for bacterial growth were classified as control. In Experiment 2, 10 multiparous cows with clinical mastitis in one or more quarters were selected. Milk samples from inflamed quarters were cultured to identify mastitis pathogens; these quarters were classified as clinical; all other quarters were classified as control. Teat canal keratin was collected from all quarters just before an a.m. milking, samples were weighed, and lipid determinations were conducted by TLC. Keratin from subclinical quarters compared with keratin from control quarters did not differ in either neutral lipid or fatty acid composition. Total lipid was significantly higher in keratin from teats of clinical quarters than in keratin from control quarters (27.8 vs. 21.5 microgram/mg). Neutral lipid composition of keratin was similar between teats from clinical quarters and teats from control quarters. In Experiment 2, quarter foremilk samples were also obtained to determine lipid composition. The FFA in milk from clinical quarters contained fewer short-chain fatty acids, whereas polyunsaturated fatty acids were significantly higher in milk from clinical quarters.

Animals↗
PubMed1992

Increased susceptibility to intramammary infection following removal of teat canal keratin.

Influence of teat canal keratin on susceptibility to intramammary infection was investigated in lactating Jersey cows. In each of two replicate trials, keratin was removed from the left teats of 20 cows immediately before milking. Immediately after milking, all teats were exposed to bacterial challenge by immersion in a suspension of Streptococcus agalactiae (5 x 10(7) cfu/ml). Bacterial challenge was repeated after the next four milkings. Foremilk samples were obtained for 8 d after keratin removal to determine infection status. A mammary quarter was classified as infected based solely upon the bacteriological criteria outlined by the National Mastitis Council. The rate of infection in quarters from which keratin was removed was greater than that in control quarters. Infection rates were 26.3% for keratin-removed quarters and 8.3% for control quarters in trial 1 and 13.5 and 0%, respectively, in trial 2. When more stringent criteria (recovery of greater than 100 cfu of S. agalactiae/ml in three or more successive milk samples and a SCC of greater than 10(6)) were used to identify a subset of infections that were clearly intramammary, infection rates were 9.3% for keratin-removed quarters and 1.4% for control quarters. Thus, partial removal of keratin from the teat canal compromised the ability of the teat to prevent passage of bacterial pathogens from the external environment into the mammary gland.

Animals↗
PubMed1992

Are poor families satisfied with the medical care their children receive?

While access to care has been shown to be worse for poor populations, few studies have examined the quality of care received by the poor vs the nonpoor. Furthermore, serious concerns have been raised about the impact of cost-containment efforts on the quality of health care for both the poor and nonpoor. The authors examine the interpersonal quality of medical care received by children from poor and nonpoor families by assessing parental satisfaction with physician-patient communication in a telephone survey of a nationally representative sample of households containing 2182 children and adolescents 17 years or younger. The majority of parents were satisfied with many aspects of their interactions with physicians. However, poor families were more likely to be not completely satisfied with the medical care their children received at their last health visit than nonpoor families (27% vs 12%, P less than .001). With regard to specific aspects of the physician-patient communication, poor families were more likely to be not satisfied with the physician's provision of information about the illness (40% vs 21%, P greater than .001); the physician's discussion of examination findings (21% vs 9%, P less than .001); and the opportunity provided by the physician to express their concerns (12% vs 6%, P less than .001). Logistic regression demonstrated that poor patients were approximately twice as likely to be not satisfied with the medical encounter and with various aspects of their communication with the physician. It is concluded that the parents of poor children are less satisfied with their care. Both policy and educational interventions may be needed to address this problem.

Adolescent↗
PubMed1991

Identification of the neurofibromatosis type 1 gene product.

The gene for neurofibromatosis type 1 (NF1) was recently identified by positional cloning. The complete cDNA encodes a polypeptide of 2818 amino acids. To study the NF1 gene product, antibodies were raised against both fusion proteins and synthetic peptides. Initial characterization of two anti-peptide antibodies and one fusion-protein antibody demonstrated a specific protein of approximately 250 kDa by both immunoprecipitation and immunoblotting. This protein was found in all tissues and cell lines examined and is detected in human, rat, and mouse tissues. To demonstrate that these antibodies specifically recognize the NF1 protein, additional fusion proteins containing the sequence specific to the synthetic peptide were generated. Both peptide antisera recognize the proper specific fusion proteins so generated. Immunoprecipitates using the peptide antisera were shown to recognize the same protein detected by immunoblotting with either the other peptide antiserum or the fusion-protein antiserum. Immunoblotting using antiserum specific to spatially distinct epitopes conducted on tissue homogenates demonstrated the NF1 protein in all adult tissues. Based on the homology between the NF1 gene product and members of the GTPase-activating protein (GAP) superfamily, the name NF1-GAP-related protein (NF1GRP) is suggested.

Amino Acid Sequence↗
PubMed1991

Lipid synthesis by co-cultures of mammary, liver, and adipose tissue explants from sometribove (recombinant methionyl bovine somatotropin)-treated dairy cows.

Bovine somatotropin was given to six lactating (230 day) cows (40 mg/day X 5-days) and excipient was given to six control cows. Mammary, liver, and adipose explants from somatotrophin and control cows were co-cultured at 37 degrees C for 24 h with 0.5 microCi [14C]acetate/ml media with or without 0.5 micrograms/ml somatotrophin. Tissue lipids were extracted with chloroform/methanol and separated by thin layer chromatography. In vivo somatotrophin increased milk production 2.4 kg/day compared to a 0.9 kg/day decrease by controls. Mammary tissue from somatotrophin cows incorporated more [14C]acetate into total lipids (4417 vs. 3016 dpm/mg tissue) than controls. Adding somatotrophin to explant cultures from somatotrophin cows further increased incorporation into total lipids (4839 vs. 3994 dpm/mg tissue). In contrast, adipose tissue from somatotrophin cows incorporated less [14C]acetate into total lipids than controls (1524 vs. 2581 dpm/mg tissue). Serum IGF-I concentration correlated well (r = 0.69) with milk output differences between Days 1 and 5 of treatment. Media IGF-I concentration correlated well (r = 0.61) with the difference in total lipid synthesis between the in vitro control and somatotrophin groups. Results support the concept that somatotrophin increases milk production by partitioning nutrients away from adipose toward mammary tissue.

Adipose Tissue↗
PubMed1991

Adherence of medium-chain fatty acids to feeding tubes of premature infants fed formula fortified with medium-chain triglyceride.

Adherence of medium-chain triglyceride (MCT) oil to feeding tubes during gavage feeding of Enfamil formula was quantitated. Infants were fed similar volumes of either unfortified formula (n = 11) or MCT oil-fortified formula (0.5 ml/oz); either the MCT oil was mixed with the formula before feeding (n = 11) or the MCT oil was delivered into the feeding tube and then was followed by formula (n = 11). The fat residue in the feeding sets was quantitated by gravimetry, and individual fatty acids were characterized by gas-liquid chromatography. The data show that only trace amounts of lipid (0.23 +/- 0.04%) adhered to feeding sets during feeding of unfortified formula. Significantly more lipid (p less than 0.0005) adhered when formula was fortified with MCT oil, and the method of feeding greatly affected lipid adherence, i.e., 1.52 +/- 0.21% when the MCT oil was followed by formula versus 10.20 +/- 1.76% when the MCT oil was mixed with formula before feeding. Analysis of the fat residue of fortified formula showed that greater than 90% was composed of C8:0 and C10:0, the major fatty acid components of MCT oil. We suggest that care be exercised when fortifying infant formula with MCT oil.

Adhesiveness↗
PubMed1991

Lipid composition of teat canal keratin collected before and after milking from Holstein and Jersey cows.

In three experiments, keratin was collected from individual teats of 40 Holstein and 20 Jersey cows immediately before and after milking. In Experiments 1 and 2, keratin collected from teats of 20 Holstein cows before milking was compared with keratin collected after milking. In Experiment 3, keratin was collected from two teats of 20 Jersey and 20 Holstein cows before milking and compared to the other two teats of the same cows after milking. All three experiments yielded similar results. In Holsteins, keratin weight before milking was 1.6 times greater than keratin weight after milking (3.1 vs. 1.9 mg). In Jerseys, only small amounts of keratin were removed during milking (3.5 mg before vs. 3.1 mg after) In Holsteins and Jerseys, neutral lipid concentration was 1.6 times greater after milking than before, suggesting that when keratin was removed during milking, only moderate amounts of lipid were removed. In Holsteins, total lipid collected per teat was similar before or after milking (59.2 vs. 48.5 micrograms). Results demonstrate that keratin collected after milking had a different lipid composition than keratin collected before milking.

Animals↗
PubMed1990

Potentially lethal ventricular arrhythmias. Minimizing the danger.

Patients with potentially lethal ventricular arrhythmias are at an increased risk of sudden death. Antiarrhythmic drugs, with the exception of beta blockers and possibly amiodarone, have not been particularly effective in reducing mortality. Beta blockers have been used successfully to treat survivors of myocardial infarction, including patients with significant impairment of ventricular function. Evidence to date suggests that use of low-dose amiodarone may be appropriate for selected patients with chronic heart failure and potentially lethal ventricular arrhythmias.

Anti-Arrhythmia Agents↗
PubMed1990

Methods of collection and lipid composition of teat canal keratin in dry and lactating cows.

Methods for collecting keratin from the teat canal were examined to select a procedure to obtain representative samples for lipid analysis. Data obtained by solvent extraction of excised teats were compared with those obtained by scraping keratin from dissected teats of lactating and dry cows. Solvent extraction with petroleum ether or 2:1 chloroform-methanol yielded similar dry weights of material. However, both solvents removed large amounts of material other than keratin from the teat canal. The lipid class and fatty acid profiles of the material extracted by solvent flushing were not similar to profiles obtained by scraping keratin from the teat canal. A metal tapestry needle was suitable for collection of keratin from the teat canal of living cows. About 78% of the keratin present in the teat was collected with the needle. Lipid composition of keratin collected with the needle was the same as in keratin scraped from excised teats. The tapestry needle was suitable as a tool for collecting repeatable, representative samples of keratin for analysis from single teat canals of living cows.

Alkanes↗