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Biomedical subjects

R Spencer

Publications and source records attributed to R Spencer.

At least 55 records · Page 3Linked to original sources
PubMed1995

Rachipagus conjoined twins: they really do occur!

The myth of rachipagus twins is hereby exploded-the myth, not the rachipagus! In a review of over 1,200 cases of conjoined twins, one classic example of rachipagus was found-two complete infants with dorsal union of the entire head and trunk, with roentgenograms showing clearly visible bony union of the vertebral arches from T6 to L3. After the typical case was discovered, 20 dorsal parasitic twins were reevaluated and reclassified as rachipagus. Two had extensive vertebral fusion and 18 were united in the dorsal midline, all with a meningocele, vertebral anomaly, and/or bony or neural connection. A theory of the embryologic origin of these twins is proposed: two embryonic discs located on diametrically opposing aspects of a single amniotic cavity becoming united in the area of the closing neural folds. This again raises the controversy concerning "fission or fusion" in conjoined twins.

Embryonic and Fetal Development↗
PubMed1995

The efficacy of Decapinol mouthwash 2 mg/mL in preventing gingivitis.

In vitro studies and early clinical trials have shown promising results for Delmopinol HCl solution as an effective mouth rinse for reducing experimentally induced gingivitis in the absence of mechanical plaque control. The efficacy of Decapinol mouthwash 2 mg/mL (Delmopinol HCl) in preventing gingivitis in a double-blind, randomized clinical study with parallel group design was studied. Forty-seven healthy young adults were randomly assigned to the Delmopinol or placebo groups. After an initial period of four weeks of intensive oral hygiene including bi-weekly professional cleaning of the teeth and oral hygiene instruction, all subjects achieved a low degree of gingivitis or a plaque score close to zero. At baseline, Bleeding on Probing, Modified Gingival Index and Plaque Index were recorded and the teeth were professionally cleaned. All forms of plaque control were then suspended and subjects were supervised in a one-minute rinsing of Decapinol mouthwash 2 mg/mL or placebo twice daily. Measurements of efficacy variables were then repeated after two and three weeks treatment and adverse events were recorded. After the study period of three weeks all previous plaque control measures were resumed. At week four, all subjects were reassessed for the resolution of gingival inflammation and where residual gingival inflammation persisted, appropriate treatment was given. Only mild and short-lasting adverse events were noted for the use of Delmopinol in the study period. However, for all teeth sites measured, significant differences between Delmopinol and placebo groups were found in Bleeding on Probing (p < 0.05) and Plaque Index (p < 0.0005).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Mortality in a cohort of homeless adults in Philadelphia.

BACKGROUND: Homeless people are at high risk for death from many causes, but age-adjusted death rates for well-defined homeless populations have not been determined. METHODS: We identified 6308 homeless persons 15 to 74 years of age who were served by one or both of two agencies for the homeless in Philadelphia between January 1, 1985, and December 31, 1988. Using a data base that contained all deaths in Philadelphia and listings of all Philadelphia residents during the same period, we compared the mortality rate for this homeless population with the rate in the general population of Philadelphia. RESULTS: The age-adjusted mortality rate among the homeless was 3.5 times that of Philadelphia's general population (95 percent confidence interval, 2.8 to 4.5). The age-adjusted number of years of potential life lost before the age of 75 years was 3.6 times higher for the homeless people than for the general population (345 vs. 97 years lost per 1000 person-years of observation). Fifty-one of the 96 deaths of homeless persons (53 percent) occurred during the summer months. Mortality rates were higher among the homeless than in the general population for nonwhites, whites, women, and men. Within the homeless cohort, white men and substance abusers had higher mortality rates than other subgroups, but even homeless people not known to be substance abusers had a threefold higher risk of death than members of the general population. Injuries, heart disease, liver disease, poisoning, and ill-defined conditions accounted for 73 percent of all the deaths among the homeless. CONCLUSIONS: Homeless adults in Philadelphia have an age-adjusted mortality rate nearly four times that of Philadelphia's general population. White men and substance abusers are at particularly high risk. Matching cohorts of homeless people to death records is a useful way to monitor mortality rates over time, evaluate interventions, and identify subgroups with an increased risk of death.

Adolescent↗
PubMed1994

Significant fiber evidence recovered from the clothing of a homicide victim after exposure to the elements for twenty-nine days.

An adhesive tape lint removal roller was used to isolate fibers from a homicide victim's clothing that had been exposed to the elements for twenty-nine days. Comparison microscopy, microspectrophotometry, and infrared analysis were used to compare recovered fibers to known fibers obtained from the suspect's shirt and the car in which it was believed the homicide occurred. Fibers recovered from the victim's clothing included specimens that were indistinguishable from fibers constituting the suspect's shirt, and others that were indistinguishable from the three distinct types of fibers comprising the upholstery, carpeting, and trunk liner of the car. The distribution of fibers on the various garments helped corroborate the crime scenario.

Adolescent↗
PubMed1993

The use of recombinant human erythropoietin in end stage renal disease.

We treated 57 patients who suffered from end stage renal disease (ESRD) with recombinant human erythropoietin (EPO) for a mean period of 56 weeks. Patients were aged between 18 and 81 years. Forty three patients were on haemodialysis and 14 on continuous ambulatory peritoneal dialysis (CAPD). Despite regular transfusions, the mean haemoglobin prior to EPO therapy was 7.4 g/dl +/- 1.7. The target haemoglobin of 10 g/dl was reached at a mean of 12 weeks for the CAPD patients and at 14 weeks for the haemodialysis population. Patients were noted during the study to have a progressive rise in mean red cell volume, and this appeared to be related to their level of iron stores. The mean dose EPO used to reach the target haemoglobin was 8,700 u/week (125 u/kg/week) for the haemodialysis patients and 7,200 u/week (102 u/kg/week) for the CAPD patients. Three patients (7%) developed thrombosis of their A/V fistula. Hypertension was exacerbated in 28% of the patients. We conclude that EPO is a very effective but not inexpensive therapy for the anaemia of ESRD.

Adolescent↗
PubMed1992

Design and synthesis of novel FKBP inhibitors.

Small molecule FKBP inhibitors were prepared with inhibitory activity ranging from micromolar to nanomolar. The design of these inhibitors derives from a structural analysis of the substrates for FKBP and cyclophilin. As a consequence of this analysis two key observations were made, namely: (1) amino ketone moieties are suitable as FKBP recognition elements at the P1-P1' site and (2) the P3'-P4' site will accept a trans-olefin as a suitable mimetic of a peptide moiety. The preparation of these non-peptide inhibitors is readily accomplished by a protocol which includes the synthesis of chiral propargylic amines and their subsequent conversion into vinyl zirconium reagents.

Amino Acid Isomerases↗
PubMed1992

Conjoined twins: theoretical embryologic basis.

A theoretical basis for the embryology of conjoined twins was formulated from clinical experience with ten cases and extensive review of pertinent embryologic and clinical literature, including over 500 cases. Regarding the age old question of fusion or fission, it is concluded that there is no known embryologic process by which conjoined twins can be formed by fission but firm evidence to support fusion in all cases. Whether the fusion occurs between embryos on one embryonic disc or on two is of no consequence since they are all monovular. Intact ectoderm will not fuse to intact ectoderm, and all seven types of conjoined twins are explained by seven possible sites of union in the early embryo. One new term is proposed: parapagus, from the Greek para, meaning "side," combined with pagus, meaning "fixed"; this is the group formerly called dicephalus or diprosopos. These anterolaterally united parapagus twins must result from two nearly parallel notochords in close proximity; craniopagi and pygopagi from fusion at the cranial and caudal neuropores, respectively; cephalopagi and ischiopagi from union at the pharyngeal and cloacal membranes, respectively; thoracopagi from merging of the cardiac anlage; and omphalopagi from fusion of the umbilicus or of the edges of two embryonic discs in any area not including the above sites. Parasitic twins result from embryonic death of one twin, leaving various portions of the body vascularized by the surviving autosite. The rarity of cases (2) not easily explained by the above theories, and the nearly 6% of twins with two umbilical cords arising from the placenta would seem to support these conclusions. Should one wish to learn the methods of a conjurer, he might vainly watch the latter's customary repertoire, and, so long as everything went smoothly, might never obtain a clue to the mysterious performance, baffled by the precision of the manipulations and the complexity of the apparatus; if, however, a single error were made in any part or if a single deviation from the customary method should force the manipulator along an unaccustomed path, it would give the investigator an opportunity to obtain a part or the whole of the secret.(ABSTRACT TRUNCATED AT 400 WORDS)

Humans↗
PubMed1992

Current concepts in retinopathy of prematurity.

Significant advances regarding understanding the etiology and treatment of retinopathy of prematurity have occurred in the 50 years since its discovery. Nevertheless, there is still a great deal to be learned. In spite of major technological advances in neonatal care, retinopathy of prematurity is a multi-factorial disease and probably cannot be completely prevented. Early intervention in the diagnosis and management of these infants has greatly improved their visual prognosis. Further studies may help pediatricians and neonatologists to understand and control associated risk factors. Ophthalmologists must continue to examine these patients early and follow them closely to control the associated treatable aspects of the disease, such as strabismus and amblyopia.

Humans↗
PubMed1992

Limiting applications of cryotherapy for severe retinopathy of prematurity.

In an effort to minimize surgical and visual morbidity of cryotherapy for retinopathy of prematurity (ROP), 18 eyes of 13 patients with 3 to 7 clock hours of stage 3 ROP with "plus" disease were treated by cryotherapy applications limited to the avascular retina adjacent to the areas of stage 3 disease. In 17 of 18 eyes, this limited use of cryotherapy was sufficient to cause regression of ROP without further treatments. After at least 3 months follow-up, ROP outcome showed a normal macular appearance in 16 eyes; two eyes developed macular dragging; no retinal detachments occurred.

Cryosurgery↗
PubMed1991

Visual outcome in infants with cicatricial retinopathy of prematurity.

Monocular grating acuities of preterm infants with retinopathy of prematurity (ROP) were measured using a forced-choice preferential-looking (FPL) procedure. Eyes were independently graded by a retinal specialist and/or pediatric ophthalmologist and assigned to anatomic outcome categories on the basis of cicatricial residua of ROP. Eyes assigned to the normal/regressed and peripheral retinal changes categories (n = 120) had normal posterior poles. The authors found that grating acuities in this group were slightly lower than those of age-matched healthy full-term infants, even when infants with amblyogenic or neurologic conditions were eliminated from the analysis. Grating acuity of eyes assigned to the macular ectopia, macular fold, partial detachment, or total detachment outcome categories (n = 60) had abnormal posterior poles, and grating acuity of these eyes was significantly related to anatomic outcome category (P less than 0.001). Follow-up data from subsets of eyes at 6 months, 12 months, or 2-5 yr after the initial acuity test suggest that early FPL acuity tests may be predictive of long-term functional outcome (r = 0.75-0.87).

Follow-Up Studies↗
PubMed1990

Vitrectomy in eyes at risk for macular hole formation.

Fifteen eyes believed to be at increased risk for macular hole formation underwent vitrectomy in an attempt to prevent macular hole formation. Full-thickness macular holes have not developed in 10 of 11 eyes with stage 1 macular holes. Four eyes were noted to have small full-thickness foveal defects (stage 2 macular holes) at the time of vitrectomy. Two of the four eyes have not progressed to macular hole formation and have 20/25 visual acuity. All patients have been followed for a minimum of 13 months (median, 18 months). The 12 eyes that have not experienced macular hole formation have had a significant (P less than 0.001) improvement in vision with seven (58%) attaining visual acuity of 20/25 or better. The postoperative foveal electroretinogram (ERG) amplitude was higher than the preoperative amplitude in five of the six eyes tested.

Aged↗