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Biomedical subjects

D W Smith

Publications and source records attributed to D W Smith.

At least 19 recordsLinked to original sources
PubMed1979

Methodology of monitored release of a new preparation: buprenorphine.

The analgesic agent Temgesic (buprenorphine) was made available under monitored release regulations for one year, which yielded data from 1736 doctors on 9123 patients. An analysis of 17 120 administrations of the drug confirmed the results of the pre-licensing clinical studies encompassing data from nine British hospitals on 483 patients. No important new adverse effects attributable to the product were observed, and apart from giving reassurance, the usefulness of monitored release is questioned in the light of the relatively small amount of additional information arising from it.

Adolescent↗
PubMed1979

The 'breech head' and its relevance.

Eight infants had scaphocephaly with prominent occipital shelving. This abnormal head shape is identified as a postural deformation associated with breech intrauterine position, and it is noted to resolve during infancy with no apparent residual impairment in most cases. At the same time, the "breech head," as we have designated this unusual head form, may occur in the setting of a primary problem in fetal morphogenesis, and it may be itself a factor contributing to birth injury during vaginal delivery of the breech infant.

Breech Presentation↗
PubMed1979

Urethral obstruction malformation complex: a cause of abdominal muscle deficiency and the "prune belly".

Abdominal muscle deficiency with a "prune belly" abdomen as been a major feature of the so-called prune belly syndrome, which has been regarded as a specific entity, although the etiology and developmental pathology are not understood. We present evidence that abdominal muscle deficiency is an etiologically nonspecific anatomic defect which is secondary to fetal abdominal distention of various causes. One of the more common causes is urethral obstruction with consequent early bladder distention, causing abdominal distention and other anomalies, a constellation of findings which we have termed the urethral obstruction malformation complex. This interpretation of the etiology of most cases of prune belly syndrome accounts for the male predominance, the observed variability in severity, and the lack of a defined mode of inheritance. Recurrence risk figures need to be redefined for each specific obstructing lesion of the urethra. The possibility of early prenatal diagnosis and management of fetuses with urethral obstruction needs further study.

Abdominal Muscles↗
PubMed1979

Monozygotic twinning and structural defects.

An excess of structural defects occurs in monozygotic twins compared in dizygotic twins or singletons. The excess is composed of three categories of defects. The first includes defects which are part of the MZ twinning, such as conjoined twins and some amorphous twins. In addition, all early embryonic malformations and malformation complexes such as sirenomelia mc. holoprosencephaly mc. and anencephaly mc are increased in MZ twins. The reason for this association is considered to be the common etiology for both the MZ twinning and the early malformation problem. MZ twins provide an excellent model for appreciating the spectra of particular malformation complexes, since the twins often have different gradations in severity of the same type of structural defect. The finding of both discordant and concordant MZ twins with Goldenhar, de Lange, and Rubinstein-Taybi syndromes suggests that these "syndromes" might be early malformation complexes. The other two categories are considered secondary to the MZ twinning process. The most unique category results from any vascular interchange between the MZ twins. Depending on their nature, vascular connections may give rise to reverse flow with acardiac status in one twin during early development, or to vascular disruptions from a deceased co-twin with intravascular coagulation causing embolization in the surviving co-twin. The latter defects may include microcephaly, porencephalic cysts, hydranencephaly, intestinal atresia, aplasia cutis, and limb amputation. Unequal growth may occur as a result of artery to vein placental anastomoses. The final category is deformations due to crowding in utero during late gestation. These do not differ from those in DZ twins.

Cardiovascular Abnormalities↗
PubMed1979

Postaxial acrofacial dysostosis syndrome.

Three patients with a postaxial acrofacial syndrome are presented; the features of these and three other previously described examples are set forth. The facies can be strikingly similar to that of the Treacher Collins syndrome. The limb deficiencies are postaxial, with absence or incomplete development of the fifth digital rays in both the upper and lower limbs. Accessory nipples have been found in most of the patients. The nature of the limb deficiencies and the accessory nipples help to distinguish this condition from Nager AFD. All of the children have normal intelligence and development; most show normal growth. All of the six cases have occurred sporadically.

Abnormalities, Multiple↗
PubMed1979

Uterine malformation and fetal deformation.

Beyond the enhanced miscarriage and prematurity associated with the structurally abnormal uterus, we have found 14 examples of fetal deformation secondary to uterine malformation with its consequent uterine constraint. In several instances the constellation of deformations had been misinterpreted as a multiple malformation disorder. One patient died of pulmonary hypoplasia, but all the survivors showed restoration toward normal form postnatally. Recognition of the basic problem allows for surgical reconstruction of the uterus, which is generally accompanied by an improved outlook for subsequent pregnancies.

Congenital Abnormalities↗
PubMed1979

Autosomal dominant microcephaly.

Four families with autosomal dominant microcephaly are reported. Although the phenotype is nondistinctive, several patients had receding or small foreheads, upslanted palpebral fissures, or prominent ears. The degree of intellectual dysfunction is not as severe as that recorded in autosomal recessive microcephaly. It would appear that autosomal dominant microcephaly is more common than previously recorded, and that head circumference measurements of siblings and parents of affected patients should become a part of the initial investigation.

Adult↗
PubMed1979

The amniotic band disruption complex: timing of amniotic rupture and variable spectra of consequent defects.

Seventy-nine patients with the amniotic band disruption complex, including 54 infants with multiple system involvement and 25 with affected limbs alone, were evaluated. No two cases of the disorder were exactly alike. Defects varied from simple digital band constrictions to major craniofacial and visceral defects; fetal death may also occur. Amniotic rupture appeared to cause injury through three basic mechanisms: (1) interruption of normal morphogenesis; (2) crowing of fetal parts; and (3) disruption of previously differentiated structure. Comparison of 35 cases in which the timing of amniotic rupture could be estimated suggests that early amniotic rupture results in multiply affected infants who are frequently aborted or stillborn, whereas later rupture results primarily in limb involvement. Our findings indicate that both the spectrum of the developmental pathology and the nature of fetal outcome are determined by the timing of amniotic rupture. Appreciation of the mechanism which explains the disparate appearances of infants with the amniotic band disruption complex will allow more acurate diagnosis and appropriate counseling with respect to the sporadic nature of the disorder.

Abnormalities, Multiple↗
PubMed1979

Isolation and mapping of plasmids containing the Salmonella typhimurium origin of DNA replication.

A purified EcoRI restriction endonuclease fragment that determines resistance to kanamycin and is incapable of self-replication was used to select autonomously replicating fragments from an EcoRI digest of a Salmonella typhimurium F' plasmid containing the chromosomal region believed to include the S. typhimurium origin of DNA replication. Both the F factor and S. typhimurium chromosome replication origins were cloned by this procedure. The EcoRI fragmentment containing the S. typhimurium origin of replication is 19.4 kilobase pairs long and includes functional asp+ and uncB+ genes. Restriction endonuclease analysis of deletions obtained from the S. typhimurium origin plasmid indicated that the replication origin (ori region) is contained within a 3.3-kilobase pair region. Comparison with Escherichia coli origin plasmids shows colinearity of gene arrangement on the chromosomes in this region and suggests that some, but not all, regions of the nucleotide sequence in the origin region may be conserved (identical) in these two bacterial species.

Chromosome Mapping↗