Biomedical subjects
Publications and source records attributed to A Shapiro.
The study of families of protein structures is important in analysing the results of NMR structure determinations and in investigating mechanisms of molecular evolution at the level of conformation. A method is discussed for finding the transformations that mutually superpose an arbitrary number of structures in the least-squares sense given specified atom-to-atom correspondence.
This paper presents a psychophysical dissection of the S-cone color system. Experiments were guided by a skeletal model that assumed a first stage consisting of S-, M- and L-cones, and a second stage of the opponent combination of the S and L+M signals. The response of the S-cone system was isolated by measuring difference thresholds between lights that were equiluminant tritanopic confusion pairs and thus differed only in S-cone excitation. Two types of mechanisms that control sensitivity in the S-cone system were identified: (i) static mechanisms that have a restricted range and thus limit discrimination to a small range of inputs; and (ii) adaptive mechanisms that change the state of the system in response to changes in steady illumination, so that the system is sensitive to small changes from the adapting light. These mechanisms were localized by lights that stimulated the S-cone system while keeping the signal constant at either the S, the L+M, or the post-opponent stage. The response function of the static mechanism was estimated by measuring difference thresholds at judgment points other than the steady adapting light. This procedure was repeated at a number of adaptation lights to examine the properties of adaptive mechanisms. The data were consistent with an elaborated model that included identical multiplicative gain control mechanisms in the S and L+M pre-opponent branches, and a post-opponent static sigmoidal nonlinearity with different amounts of compression for positive and negative opponent inputs.
Extracorporeal shock-wave lithotripsy (ESWL) has been accepted as the method of choice for most upper urinary tract calculi. However, in cases of stones in the lower ureter, ureteroscopic procedures have generally been preferred. Using the Dornier HM3 lithotriptor with modifications in the patient's position, we were able to successfully treat 155 unselected cases of lower ureteral calculi. The average stone size was 9.6 mm (range 5-23 mm). One hundred forty-three patients had stones located below the lower margin of the sacroiliac joint. These patients were placed in a supine position. The stones were visualized radiologically without use of a ureteral catheter in 78 percent of the patients; in 22 percent a ureteral catheter was inserted prior to ESWL to aid in stone localization. In 145 patients (94%) treatment was completed in one session; 10 patients (6%) required two sessions. Of the patients, 38 percent were free of stones one day after ESWL; 97 percent became stone free within three months, and only 3 patients required endoscopic manipulation, after ESWL. Twelve patients had stones in the midureter overlying the sacroileum. They were placed in the prone position, and the calculi were visualized with the aid of a ureteral catheter. All these patients became free of stones one month after treatment. There were no significant treatment-related complications except for bacteremia in 1 case. In view of the remarkable efficacy, negligible complication rate, and shorter hospital stay as compared to ureteroscopic stone manipulations, we recommend high energy ESWL as the primary monotherapy of mid and lower ureteral stones.
The intravesical instillation of lidocaine solution has been used as a topical form of anesthesia for bladder biopsies. We performed 63 ambulatory procedures in which multiple cold-cup biopsies were obtained during cystoscopy. There was no need for electrocautery. All patients tolerated the procedure well and were discharged from the office immediately thereafter. There were no changes in heart rate or blood pressure during the procedures. Serum concentrations of lidocaine were measured in 10 patients at 5, 10 and 30 minutes, and they were clinically insignificant. This simple office procedure can be used for the diagnosis and followup of patients with carcinoma in situ of the bladder.
Many disease loci have been linked to the telomeric end of the long arm of the human X-chromosome, Xq28. We have isolated and sequenced cDNA sequences corresponding to two novel genes that map to Xq28. These genes, c6.1A and c6.1B, are transcribed in opposite directions from a CpG island that lies approximately 70 kilobases (kb) upstream (5') of the factor VIII locus. One of these genes, c6.1A, is highly conserved between species and expressed abundantly in many human and mouse tissues, whereas, c6.1B is moderately conserved and has a restricted tissue distribution of expression. The Xq28 gene c6.1A has an autosomal homologue that is transcriptionally inactive in B-cell lines. An open reading frame (ORF) predicting a peptide of 293 amino acids is observed for c6.1A but c6.1B does not possess a single long ORF. No striking homologies to existing genes could be found for either of the two new loci. Expressed sequences that are physically close to the factor VIII gene are candidates for disease loci that map to this region of Xq28. The relevance of these genes to disease loci was investigated using DNA and RNA from hemophilia A patients bearing deletions that extend in a 5' direction away from factor VIII. The results imply that neither of these genes are primarily responsible for the development Xq28-linked diseases. However, c6.1A and c6.1B define a region of Xq28 that is deleted in two brothers that suffer from mental handicap and dysmorphism as well as hemophilia A. Thus, this region is likely to contain loci that are important for physical and mental development.
This report provides our initial experience in islet isolation and intrahepatic allotransplantation in 21 patients. In group 1, 10 patients underwent combined liver-islet allotransplantation following upper-abdominal exenteration for cancer. In group 2, 4 patients received a combined liver-islet allograft for cirrhosis and diabetes. One patients had plasma C-peptide greater than 3 pM and was therefore excluded from analysis. In group 3, 7 patients received 8 combined cadaveric kidney-islet grafts (one retransplant) for end-stage renal disease secondary to type 1 diabetes mellitus. The islets were separated by a modification of the automated method for human islet isolation and the preparation were infused into the portal vein. Immunosuppression was with FK506 (group 1) plus steroids (groups 2 and 3). Six patients in group 1 did not require insulin treatment for 5 to greater than 16 months. In groups 2 and 3 none of the patients became insulin-independent, although decreased insulin requirement and stabilization of diabetes were observed. Our results indicate that rejection is still a major factor limiting the clinical application of islet transplantation in patients with type 1 diabetes mellitus, although other factors such as steroid treatment may contribute to deteriorate islet engraftment and/or function.
Two out of 60 conjunctival epithelial tumours reviewed between 1973 and 1989 were found to be pigmented. One tumour was a pigmented papilloma and the other a pigmented squamous cell carcinoma. The melanin pigment was found in epithelial tumour cells as well as in macrophages, dendritic melanocytes, and Langerhans cells. The distinction between the latter two types of cells was possible in one of the tumours only. Both tumours were found in dark-skinned white patients without any evidence of conjunctival acquired melanosis.
In the present study, we examined letter detection in very frequent function-word sequences. It has been claimed that such sequences are processed in a unitized manner, thus preempting access to their constituent letters. In contrast, we showed that letter detection in the words for and the (1) was no more difficult when the words appeared in adjacent locations in a sentence (familiar) than when they appeared apart (less familiar sequence) and (2) was contingent upon the words' syntactic roles within the phrase. Thus, letter detection in for was easier when the sequence was separated by a clause boundary than when the words were part of the same clause. The advantage derived from clause separation was strongest when a comma divided clauses. These results challenge the unitization account of the "missing-letter" effect in common phrases and support a position where this phenomenon is seen to reflect the extraction of phrase structure during reading.
We present the successful treatment of tubo-ovarian abscesses in three young patients by continuous percutaneous drainage, inserted under the guidance of real-time ultrasonography using only local anesthesia. Each patient had been diagnosed laparoscopically as suffering from acute pelvic inflammatory disease, but had formed abscesses despite extensive broad-spectrum antibiotic therapy. One case involved a complication of the ovum pick-up procedure; the woman had tubo-ovarian abscesses with infected hematomas. Because the abscesses were localized anteriorly in the lower abdomen and did not reach the pouch of Douglas, they could not be drained through a posterior colpotomy. Ultrasound guidance allowed us to drain all the areas of the multioculated abscesses. We suggest that percutaneous abscess drainage be the initial treatment of choice for tubo-ovarian abscesses before laparotomy is considered.
Although numerous reports show that the sensitivity of the S cone system is decreased in diabetic patients, few studies have been directed toward identifying the possible sites of the sensitivity loss. In this study, a psychophysical technique was used to test hypotheses about sites of S cone system sensitivity loss in a group of patients with early diabetic retinopathy. A model of the S cone system was assumed and the experimental conditions were chosen to distinguish between explanations for S cone sensitivity loss at the receptor level from explanations for loss at a post-receptoral level. Within the context of the model, the data were consistent with S cone system sensitivity loss occurring at a post-receptoral level.
The juxtacanalicular connective tissue (JCT) is widely believed to generate the bulk of aqueous humor outflow resistance, while the pores of the inner wall endothelium are thought to generate at most 10% of this resistance in humans. However, the hydrodynamic interaction of these two components of the aqueous outflow system, which arises because of their spatial proximity, has only recently been considered. Modelling the JCT as a homogeneously distributed porous material upstream of a low porosity filter (the inner wall endothelium), the pores of the inner wall are found to cause a "funneling effect," in which the aqueous humor flows preferentially through those regions of the JCT nearest the inner wall pores. The bulk of the pressure drop occurs in the immediate proximity of the pores (within three pore radii). This greatly increases the apparent flow resistance of the JCT. For a set of parameters characterizing the normal eye, this enhancement is approximately 30-fold. The conclusion of this study is that changes in inner wall porosity may greatly affect aqueous outflow resistance, despite the low flow resistance of the inner wall pores themselves.
To avoid the complications associated with anterior chamber intraocular lenses and iris-fixated posterior chamber lenses when challenged with inadequate capsular or zonular support, we have developed a new method of measured external transscleral suture fixation of posterior chamber intraocular lenses within the ciliary sulcus. This technique differs from most current techniques of transscleral fixation, which involve passing needles through the corneoscleral wound into the ciliary sulcus without direct visualization and out through the sclera. Our technique offers a more predictable placement of suture within the ciliary sulcus and avoids damage to corneal endothelium, ciliary body, or other ocular structures.
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Over the past decade, the use of free flap transfers in head and neck surgery has led to remarkable advances in the reliability and the ultimate results of oromandibular reconstruction. Stable and retentive dental restorations have been achieved using enosseous implants placed directly into the vascularized bone flaps. However, the functional assessment of patients who underwent primary mandibular reconstruction with these techniques has not been previously reported. A group of 10 reconstructed and 10 nonreconstructed segmental hemimandibulectomy patients were compared using a battery of tests to assess their overall well-being, cosmesis, deglutition, oral competence, speech, length of hospitalization, and dental rehabilitation. In addition, objective measures of the masticatory apparatus (interincisal opening, bite force, chewing performance, and chewing stroke) were used to compare these two groups as well as normal healthy subjects and edentulous patients restored with conventional and implant-borne dentures. The results show a clear advantage for the reconstructed patients in almost all categories. Persistent problems and future directions in oromandibular reconstruction are discussed.
A case of peripheral ossifying fibroma is presented. The important clinical and histological features are discussed, along with the differential diagnosis, treatment and prognosis.
We treated 12 patients with sixteen renal and one ureteral cystine stones primarily with extracorporeal shock-wave lithotripsy (ESWL). Among the stones thirteen were greater than 25 mm. In four stones less than 25 mm, three stones completely disappeared and 1 was reduced to small fragments, following ESWL. In thirteen stones greater than 25 mm, twelve were treated by ESWL initially, and one by surgery. Of the 12 cases treated initially by ESWL, 4 became stone-free, 4 remained with small fragments, and 1 remained with large fragments. Two patients were operated on because of poor response to ESWL and 1 patient lost kidney function because of prolonged obstruction. Disintegration of cystine stones greater than 25 mm required an average of 8,522 shock-waves in 4.33 sessions. The problems associated with application of ESWL monotherapy to cystine stones are presented.
Complete rupture of the female urethra is rare. We found only 30 such cases described in the literature, 19 of which were in children. In most of these patients, the proximal urethra and bladder neck were injured. Herein we report on the complete rupture of the distal part of the urethra in a female child with a pelvic fracture. This diagnosis should be considered in such cases with deep vaginal lacerations, inability to void, and with unsuccessful catheterization.
Of the factor IX sequence changes that we have identified in 65 consecutive males with haemophilia B, 11 (17%) are the same mutation. This mutation is a T----C transition at base 31311 which substitutes threonine for isoleucine397 (ile397) in the factor IX molecule. The 11 patients are of Western European descent and have the same haplotype: Hinf1 (-), Xmn1 (-), Taq1 (-), BamH1 (+), Malmö allele = thr148. The frequency of this haplotype was estimated and the probability of the same mutation occurring independently 11 times in this haplotype was miniscule. We conclude that these patients have a common ancestor despite the lack of overlapping pedigrees. The clinical symptoms of the disease were consistently moderate/mild in these 11 patients, whereas factor IX coagulation values obtained from the medical records varied more than sixfold between individuals. However, when plasma from five individuals was assayed by the same laboratory concurrently, the values varied less than twofold. Thus, in routine practice, clinical severity may correlate better with the presence of a given mutation than the factor IX coagulant activity. The high frequency of the mutation at ile397 indicates that carrier testing in families of Northern European descent with moderate/mild haemophilia B can be expedited by first determining whether this particular mutation is present. We demonstrate here that the technique of polymerase chain reaction (PCR) amplification of specific alleles (PASA) can be used to rapidly perform carrier testing in families with the ile397 mutation.