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Biomedical subjects

M B Lewis

Publications and source records attributed to M B Lewis.

At least 19 recordsLinked to original sources
PubMed1997

The Thatcher illusion as a test of configural disruption.

Bartlett and Searcy's recent account for the Thatcher illusion suggests that inversion impairs holistic facial information. This illusion is used to compare the effects of inverting and negating faces. Subjects made a speeded response to whether just the mouth and the eyes of a face have been inverted. Performance was found to be slower when faces were inverted rather than upright. Presenting faces in photographic negative also hindered performance implying that this transformation also disrupts holistic facial information.

Analysis of Variance↗
PubMed1995

"He calls me his angel of mercy": the experience of caring for elderly parents in the home.

The purpose of this qualitative ethnography was to describe the experience of caregivers who resided with their elder dependent parents and to discover caregiver needs. Five women between the ages of 35 and 73 years who cared for and shared residence with their dependent elder parents participated in the study. As prescribed by Field and Morse's method of data analysis, interviews were transcribed verbatim, and concepts and subconcepts were discovered in the data. The findings reflecting the experience of caregiving and a discovery of caregiver needs assisted in identifying three concepts--needs, motivation, and helpers/hindrances--and six subconcepts--quiescence, emancipation, love for parent, avoiding institutionalization, family, and formal support. These concepts and subconcepts contributed to the development of the model of kin-keeper for caregivers. This model has consideration as a level I theory. It offers to nursing an explanation of the behaviors of caregivers and provides an improved understanding of the process of caregiving as related to holistic nursing practice. Further research and development of the model to a level I theory are recommended, as is the use of a larger and more diverse population.

Adult↗
PubMed1993

Serine for glycine substitutions in type I collagen in two cases of type IV osteogenesis imperfecta (OI). Additional evidence for a regional model of OI pathophysiology.

Serine for glycine substitutions in type I collagen have been described in seven cases of lethal type II osteogenesis imperfecta (OI), and six cases of nonlethal OI. We describe here two cases of moderately severe type IV OI with serine substitutions at alpha 1(I) Gly352 and alpha 2(I) Gly922, respectively. In both cases, G-->A point mutations were detected by RNase A cleavage of RNA/RNA and RNA/DNA hybrids. These cases extend the location for serine substitutions producing the moderately severe OI phenotype to the alpha 2(I) chain and the amino-terminal end of the alpha 1(I) chain. Their location supports a regional model of OI pathophysiology for serine substitutions. The proband with alpha 2(I) Gly922-->Ser has both normal and overmodified forms of both type I collagen chains. The overmodified form has delayed migration of all CNBr peptides. Helix thermal stability is decreased 4 degrees C. The fibroblast collagen protein and RNA of her unaffected parents are normal. However, the father was demonstrated to be a mosaic carrier using leukocyte DNA. The fibroblasts of the proband whose serine substitution is at alpha 1(I) Gly352 synthesize type I procollagen chains with delayed electrophoretic migration; normally migrating forms are difficult to detect. Only alpha 1(I) CB 8 displayed delayed migration. Helix thermal stability is reduced 2 degrees C. Parental genomic DNA was normal.

Amino Acid Sequence↗
PubMed1993

Moderately severe osteogenesis imperfecta associated with substitutions of serine for glycine in the alpha 1(I) chain of type I collagen.

We have examined the type I collagen protein, RNA, and cDNA of 2 children with moderately severe (type IV) osteogenesis imperfecta (OI). They have in common a non-lethal form of OI with ambulatory potential, overmodification of type I collagen protein, and a substitution of serine for glycine in the collagen chain produced by one alpha 1(I) allele. The first child (Marini et al.: J Biol Chem 264:11893-11900, 1989) is now 7 years old, with the height of a 3-year-old. Her course includes significant remodeling of lower long bones and 4 femur fractures. She walks independently. A mishmatch was detected in her alpha 1(I) mRNA using RNA/RNA hybrids; it was demonstrated to be due to a G-->A point mutation in one allele of alpha 1(I), resulting in the substitution of serine for glycine 832. The second child is now 6 1/2 years old, with the height of 1 1/2-year-old. Her history includes significant bowing of femurs and tibias, 6 femur fractures, S-curve scoliosis, compression of all lumbar vertebrae, and limited short-distance walking with braces. Her alpha 1(I) mRNA has also been studied by RNA hybrid analysis; there is a single G-->A change in one alpha 1(I) allele causing the substitution of serine for gly 352. Both children have moderately severe OI. However, the serine substitution at gly 352 is associated with a more severe phenotype then is the serine substitution at gly 832. Compared to substitutions described in other cases of OI, the serine 352 is located in the middle of a cluster of cysteine substitutions associated with non-lethal OI.(ABSTRACT TRUNCATED AT 250 WORDS)

Child↗
PubMed1993

A de novo G+1-->A mutation at the alpha 2(I) exon 16 splice donor site causes skipping of exon 16 in the cDNA of one allele of an OI type IV proband.

We have investigated the procollagen, collagen, alpha 2(I) mRNA, and DNA of a proband with type IV OI. The proband synthesized two alpha 2(I) chains, one with normal electrophoretic migration and one more rapidly migrating. The fast alpha 2(I) chain was relatively retained within the cell and was present in collagens synthesized in the presence of alpha,alpha'-dipyridyl. The alpha 2(I) cyanogen bromide peptide CB 4-2 contained both normal and rapidly migrating components. Thermal stability of helices containing the rapidly migrating alpha 2(I) chain was reduced 6 degrees C. Parental fibroblast collagens were normal. RNA/RNA hybrids between proband total RNA and antisense riboprobe complementary to alpha 2(I) nt 236-1390 were digested with RNase A and T1. Digestion products seen exclusively in the proband suggested a structural change in the region coding for exons 16-19. The region which hybridized to the riboprobe was amplified using RNA-PCR and subcloned. Multiple restriction enzyme digestions of the two subcloned alleles suggested a structural change localized to the region coding for exons 16-17. Sequencing revealed a deletion of the 54 bp comprising exon 16 in the cDNA of one allele. The region of the proband's genomic DNA spanning exons 15-17 was amplified by PCR. The subcloned genomic fragments of each allele were distinguished by RNA/DNA hybrid analysis using a riboprobe complementary to normal genomic DNA from this region. Sequencing revealed a G+1-->A mutation at the exon 16 donor site in one allele. The mutation eliminates a StyI site.(ABSTRACT TRUNCATED AT 250 WORDS)

Alleles↗
PubMed1993

Unilateral cleft lip repair. Z-plasty.

All unilateral clefts of the lip are not alike. The deficiencies that exist, especially in the lateral lip element, can vary considerably. Because of these differences, it is unreasonable to expect one technique of repair to satisfy all situations. In more difficult complete unilateral cleft lip deformity, the Z-plasty repairs described in this article better satisfy the goals of this surgery.

Anthropometry↗
PubMed1991

Familial holoprosencephaly associated with a translocation breakpoint at chromosomal position 7q36.

A familial balanced t(7;9) (q36;q34) was reported recently. Analysis of the craniofacial features of 3 of the sibs showed signs of holoprosencephaly. Two of the sibs have an unbalanced derivative chromosome leading to del(7) (q36) and dup(9) (q34), while the other has a cytogenetically balanced translocation. These findings, together with several reports associating holoprosencephaly with terminal 7q deletions, indicate that a putative locus for holoprosencephaly resides at or near 7q36. It should now be feasible to clone this locus.

Adolescent↗
PubMed1990

Detection of point mutations in type I collagen by RNase digestion of RNA/RNA hybrids.

We have developed a strategy for the detection, localization and sequence determination of point mutations in the mRNA coding for the alpha 1(I) and alpha 2(I) chains of type I collagen. Point mutations are detected by RNase A cleavage of mismatches in RNA/RNA hybrids. The mRNAs coding for the fibrillar collagens present special problems for hybrid analysis because of their large size and their GC-rich and repetitive sequences. We have generated a series of overlapping antisense riboprobes covering the entire pro alpha 1(I) and pro alpha 2(I) mRNAs. Uniformly labelled normal antisense riboprobes are hybridized with the total fibroblast RNA of patients with possible mutations in type I collagen. Mismatches in the resulting RNA/RNA hybrids are cleaved with RNase A and the labelled riboprobe cleavage products are examined electrophoretically. The sensitivity and specificity of the system were demonstrated by the detection and localization of a known point mutation in the codon for alpha 1(I) glycine 988 (1). DNA for sequencing the mutations localized by hybrid analysis may be obtained by either (1) generation of a fibroblast cDNA library and isolation of both alleles by plaque screening, or (2) a more rapid method using first strand cDNA synthesis from poly (A+)-mRNA, followed by PCR amplification of the mutation-containing region of the DNA/RNA hybrid. This strategy for detection and isolation has wide application not only for mutations causing connective tissue disorders, but also for mutations in other large and repetitive genes. We have used this strategy for the detection and sequencing of a point mutation in alpha 2(I) mRNA associated with a case of lethal osteogenesis imperfecta. The G----A point mutation in the codon for alpha 2(I) glycine residue 805 results in the substitution of an aspartic acid at this position and is consistent with the proband's collagen protein data.

Alleles↗
PubMed1990

Analysis of cultured chorionic villi in a case of osteogenesis imperfecta type II: implications for prenatal diagnosis.

We examined collagens produced by cultured cells from skin, chorionic villi, and placental membranes of a 32 week fetus with osteogenesis imperfecta (OI) type II. We observed that skin fibroblasts synthesized two populations of pro alpha 1(I) chains of type I procollagen; one population was normal, while the other population had excessive post-translational modification. The thermal stability of helices containing the overmodified chains was reduced 1-2 degrees C. Most significantly, the cells cultured from chorionic villi produced type I collagen chains with the same electrophoretic abnormalities as the skin collagen. This suggests that chorionic villus sampling (CVS) is a means of prenatal diagnosis for families with a previous type II or type IV OI infant.

Cells, Cultured↗
PubMed1990

Effects of amiloride on alveolar epithelial PD and fluid composition in rabbits.

To look for evidence of active absorption of Na+ in the alveolus in vivo in air-filled lungs, we measured [K+] and [Cl-] in the alveolar lining fluid and the potential difference (PD) across the alveolar epithelium by puncturing alveoli in lungs of anesthetized rabbits with nonselective and ion-selective microelectrodes. After intravenous doses of amiloride, the PD and [K+] decreased (-1.0 +/- 0.3 to -0.3 +/- 0.1 mV, 7.4 +/- 1.1 to 4.2 +/- 0.4 meq/l, P less than 0.001), but [Cl-] did not change (96 +/- 9, 94 +/- 4 meq/l). In another set of experiments, the PD was measured with microelectrodes filled with an electrolyte solution, and midway through each measurement some of the solution was injected into the alveolar lumen. Injecting the solution without amiloride did not alter the alveolar PD (-1.0 +/- 0.4 before and -1.1 +/- 0.5 after injection). The alveolar PD decreased to -0.1 +/- 0.2 mV after injecting the solution with 10(-5) M amiloride into the alveolar interior. These results support the hypothesis that alveolar epithelium in air-filled lungs actively absorbs sodium in vivo, which accounts for the majority of the transepithelial PD.

Amiloride↗
PubMed1989

Osteogenesis imperfecta type IV. Detection of a point mutation in one alpha 1(I) collagen allele (COL1A1) by RNA/RNA hybrid analysis.

We have identified a point mutation in one alpha 1(I) collagen allele (COL1A1) of a child with the type IV osteogenesis imperfecta phenotype. When compared to parental and control samples, skin fibroblasts of the proband synthesized two populations of type I collagen molecules. One population was normal; the other was delayed in secretion and electrophoretic migration due to post-translational overmodification. Two-dimensional gel electrophoresis of the CNBr peptides demonstrated a gradient of overmodification beginning near the carboxyl-terminal CB peptides. This predicts that the mutation delaying helix formation is near the carboxyl-terminal end of one of the component chains of type I collagen. The mRNA of the patient was probed with overlapping antisense riboprobes to type I collagen cDNA. Cleavage of a mismatch in RNA/RNA hybrids of RNase A allowed the location of the mutation to a 225-base pair region of alpha 1(I) cDNA. The mismatch was not present in RNA/RNA hybrids from either parent. This region of both alpha 1(I) alleles of the patient was isolated by screening a lambda ZAP cDNA library. Sequence determination of both alleles demonstrated a single nucleotide change, G----A, resulting in the substitution of a serine for a glycine at amino acid residue 832. This point mutation occurs in the coding region for alpha 1(I) CB6 and is concordant with the protein data. The finding of a glycine substitution in an alpha 1(I) chain of a patient with the milder type IV osteogenesis imperfecta phenotype requires modification of current molecular models for types II and IV osteogenesis imperfecta.

Alleles↗
PubMed1988

Calcium increases in pulmonary alveolar fluid in lambs at birth.

Calcium concentration in fetal lung fluid in lambs is relatively low, about 1.0 mEq/liter, and its concentration in alveolar fluid in mature rabbits is about 3 mEq/liter. To see if the Ca++ concentration changes at birth, we measured alveolar Ca++ as soon as possible after delivery by cesarean section and the onset of ventilation in eight anesthetized lambs at 144 days gestation. Subpleural alveoli were punctured with Ca++ selective microelectrodes as soon as 4 min and as late as 220 min after the onset of mechanical ventilation. The [Ca++] was 1.2 +/- 0.2 mEq/liter (mean +/- SD, n = 8) in fetal lung fluid collected before ventilation. After about 25 min of ventilation, alveolar Ca++ was not different from that in term lambs 24 to 72 h old (3.3 +/- 0.6 mEq/liter, n = 8). The [Ca++] increased with a t1/2 of about 10 min. Thus, alveolar Ca++ assumes a mature character very rapidly after the start of breathing in term lambs.

Animals↗
PubMed1986

Differential production of SRIF 14 and 28 by fetal rat hypothalamic cells enriched by velocity sedimentation.

Dispersed day-17 fetal rat hypothalamic cells have been enriched according to size by velocity sedimentation prior to culture, and the SRIF production by these enriched populations was compared with that of other enriched cell fractions and with mixed-cell cultures. Cultures of mixed cells produced 100-400 pg SRIF/10(6) cells/4 h over a period of 28 days. Total SRIF production by mixed cells was inversely proportional to seeding density over the range 0.25-1 X 10(6) cells/ml/well and SRIF 14 and 28 were secreted in a ratio of approximately 6:1. Although secretory rates by low cell densities remained higher than those by high cell densities, SRIF production decreased with time at all seeding densities (up to 21 days). Dispersed fetal hypothalamic cells were enriched according to size by allowing them to sediment over 4 h through a shallow gradient of BSA in culture medium and subsequent cell fractions developed widely differing morphologies in monolayer cultures. In contrast to mixed-cell cultures, SRIF production at 8 days by both large and small cells were directly proportional to initial seeding density. Furthermore, the smaller cells secreted very much less SRIF than the larger cells (100 pg/10(6) cells/4 h vs. 1,300 pg/10(6) cells/4 h), whereas there was little difference in overall SRIF content (350 pg/10(6) cells vs. 400 pg/10(6) cells). Characterisation by HPLC of the SRIF content and secretion of smaller cells revealed SRIF 14 to 28 ratios of 7:1 and 3:1, respectively. In contrast in the large cells, the ratio was 1:1 for both content and secretion. Therefore, these cell groups contain and secrete different proportions of these 2 molecular forms of SRIF.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Clinical experience with the Robin sequence.

In 1980 the results of a trial program of intense non-surgical management on ten consecutive newborn infants admitted with the Robin sequence were reported. The diagnosis of Robin sequence was made based upon the presence of retrognathia and glossoptosis in a newborn infant with or without cleft palate. Upper airway obstruction and feeding difficulties were also present in the post natal and neonatal period. An additional 15 patients were managed using the same protocol. These 25 consecutive patients are divided into two distinct groups. Seventeen have the isolated Robin sequence (IRS) and eight have the Robin sequence as part of a syndrome or associated with multiple congenital anomalies (RSS). A definite trend showing normal growth and development in the isolated Robin sequence is noted.

Airway Obstruction↗
PubMed1981

Ectrodactyly, cleft lip and palate in two half sibs.

Two half sibs with bilateral complete cleft lip and complete cleft of the palate associated with ectrodactyly of the hands and feet, born to the same phenotypically normal mother, are reported. The younger of the two sibs also has dominantly inherited tremors (also referred to as essential heredofamilial tremors) as did her biological father. Possible genetic causes to explain the recurrence of the facial and limb malformations in the half sibs with additional central nervous system malformations in the younger sib are discussed.

Child↗
PubMed1981

The prevalence of congenital heart disease among the population of a metropolitan cleft lip and palate clinic.

The entire infant population of the Tufts-New England Medical Center Cleft Palate Clinic was reviewed, and the prevalence rates of congenital cardiac anomalies were calculated. The overall prevalence rate of congenital heart disease among the facial cleft clinic population was 6.7%, with a prevalence rate of 9.1% among patients with submucous cleft palate, 7.7% with congenital palato-pharyngeal incompetence, 0% with cleft lip only, 5.3% with unilateral cleft lip and palate, 12.5% with bilateral cleft lip and palate, 4.3% with cleft palate only, 13.6% with Pierre-Robin anomaly, 7.1% with cleft lip and palate and a syndrome diagnosis, 16.7% with cleft palate and a syndrome diagnosis.

Child↗