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Biomedical subjects

J L Stone

Publications and source records attributed to J L Stone.

At least 37 records · Page 2Linked to original sources

John Bingham Roberts and the first American monograph on human brain surgery.

JOHN BINGHAM ROBERTS (1852-1924) of Philadelphia was an active general surgeon in the latter 19th and early 20th centuries. He made pioneering contributions to a number of areas of surgery. From 1880 until the end of his career, he was one of the few American surgeons to advocate an aggressive exploratory approach to cranial fractures in an effort to avoid consequences such as infection, delayed seizures, and insanity. In his 1885 article in the Transactions of the American Surgical Association titled "The Field and Limitation of the Operative Surgery of the Human Brain," he predicted that with antiseptic precautions and the growing knowledge of cerebral localization, operations on the brain would become commonplace. This work predated that of Horsley, Keen, and many others. Roberts had a continuing interest in head injuries, cranial fractures, and the development of trephines and burrs for reconstructive cranial work, but his active enthusiasm for brain surgery diminished in the 1890s. Nevertheless, Roberts was a very prolific teacher and leader in American surgery who is perhaps best remembered for his monographs and textbooks on general, orthopedic, plastic, and reconstructive surgery.

Brain↗

Correlated conformational fluctuations during enzymatic catalysis: Implications for catalytic rate enhancement.

Correlated enzymatic conformational fluctuations are shown to contribute to the rate of enhancement achieved during catalysis. Cytidine deaminase serves as a model system. Crystallographic temperature factor data for this enzyme complexed with substrate analog, transition-state analog, and product are available, thereby establishing a measure of atomic scale conformational fluctuations along the (approximate) reaction coordinate. First, a neural network-based algorithm is used to visualize the decreased conformational fluctuations at the transition state. Second, a dynamic diffusion equation along the reaction coordinate is solved and shows that the flux velocity through the associated enzymatic conformation space is greatest at the transition state. These results suggest (1) that there are both dynamic and energetic restrictions to conformational fluctuations at the transition state, (2) that enzymatic catalysis occurs on a fluctuating potential energy surface, and (3) a form for the potential energy. The Michaelis-Menten equations are modified to describe catalysis on this fluctuating potential energy profile, leading to enhanced catalytic rates when fluctuations along the reaction coordinate are appropriately correlated. This represents a dynamic tuning of the enzyme for maximally effective transformation of the ES complex into EP.

Algorithms↗

Tau neutrinos favored over sterile neutrinos in atmospheric muon neutrino oscillations.

The previously published atmospheric neutrino data did not distinguish whether muon neutrinos were oscillating into tau neutrinos or sterile neutrinos, as both hypotheses fit the data. Using data recorded in 1100 live days of the Super-Kamiokande detector, we use three complementary data samples to study the difference in zenith angle distribution due to neutral currents and matter effects. We find no evidence favoring sterile neutrinos, and reject the hypothesis at the 99% confidence level. On the other hand, we find that oscillation between muon and tau neutrinos suffices to explain all the results in hand.

Journal Article↗

Utilization of local jails and general hospitals by state psychiatric center patients.

The idea that the deinstitutionalization of state psychiatric centers has resulted in increased utilization of general hospitals and correctional facilities by people with severe and persistent mental illness is widely held. This hypothesis of trans-institutionalization was tested by examining hospitalization and incarceration rates of people who had been or would be institutionalized in state psychiatric centers in 16 upstate New York counties. The results do not support the hypothesis of trans-institutionalization. Assumptions underlying the hypothesis are examined, potential explanations for the observed patterns are discussed, and areas for further research are suggested.

Cohort Studies↗

Gastrointestinal disorders of the fetus.

The approach to developing a differential diagnosis to an abnormal gastrointestinal ultrasound finding should include consideration of the lesion's location, size, shape, and echogenicity; fetal gender; relationship to and understanding of adjacent structures; and the presence of associated anomalies. Once a differential diagnosis has been established, ancillary testing, such as amniocentesis, maternal serology, or fetal echocardiography should be undertaken to refine further the diagnosis. A multidisciplinary team approach should be taken in the prenatal management of a suspected fetal anomaly. This may include collaboration with specialists in the fields of perinatology, prenatal ultrasound, genetic counseling, neonatology, pediatric surgery, and patient support groups.

Diagnosis, Differential↗

Chorionic villus sampling before multifetal pregnancy reduction.

OBJECTIVE: This study was undertaken to determine the technical feasibility and accuracy of chorionic villus sampling before multifetal pregnancy reduction and to determine whether sampling increases the pregnancy loss rate after the reduction procedure. STUDY DESIGN: Between January 22, 1986, and January 20, 2000, a total of 1183 patients underwent first-trimester multifetal pregnancy reduction at Mount Sinai Medical Center. Chorionic villus sampling was attempted in 86 patients before the reduction procedure. Information on the technical success and accuracy of chorionic villus sampling, as well as pregnancy outcome, was collected on all patients. Pregnancy loss rates before 24 weeks' gestation in patients undergoing chorionic villus sampling before multifetal pregnancy reduction were compared with rates in patients not undergoing sampling. RESULTS: Chorionic villus sampling was successfully completed in 85 (98.8%) of 86 patients in whom sampling was attempted. Of 166 fetuses, 165 (99.4%) were successfully sampled. Of 165 fetuses, 3 (1.8%) had karyotypic abnormalities. Sampling errors were probably made in 2 (1.2%) of 165 fetuses. Of the 73 patients who have been delivered or are beyond 24 weeks' gestation, only 1 patient (1.4%) had a pregnancy loss after the multifetal pregnancy reduction. CONCLUSIONS: Chorionic villus sampling before multifetal pregnancy reduction is technically feasible and accurate, with an acceptably low sampling error rate. Chorionic villus sampling before multifetal pregnancy reduction appears to be safe and does not increase the risk of loss after the reduction procedure.

Adult↗

Heritability of stigma position and the effect of stigma-anther separation on outcrossing in a predominantly self-fertilizing weed, Datura stramonium (Solanaceae).

A polymorphism for anthocyanin production was used as a genetic marker to document the relationship between anther-stigma separation and outcrossing rate in the predominantly self-fertilizing weed Datura stramonium. White-flowered plants that differed in anther-stigma separation were placed into populations consisting exclusively of purple-flowered plants. Self vs. outcross origin of progeny was evident in the hypocotyl color of the seedlings. Outcrossing rates measured for single flowers were significantly positively correlated with anther-stigma separation, albeit with some scatter around the regression line, especially for flowers with exserted stigmas. We also performed an 8 × 8 diallel cross to determine whether anther-stigma separation is genetically determined. Heritability in two field plots was ∼0.3 and in the greenhouse was ∼0.2. Maternal effects, epistasis, and dominance appeared to be relatively unimportant. Genotypes performed consistently across the three environments, although total plant size varied more than fivefold. It appears that the mixed-mating system of D. stramonium has a heritable basis and would be capable of responding to selection.

Journal Article↗

Does anthocyanin affect outcrossing rates in Datura Stramonium (Solanaceae)?

In this paper, I investigate whether the presence or absence of anthocyanin is neutral with respect to reproduction in Datura stramonium. The observations concern the portion of the life cycle spanning pollination to germination. Pollinators do not appear to distinguish between floral morphs, as revealed by nonbiased distribution of fluorescent powder used as a pollen analogue. Pollen-tube growth is also equal for the two morphs. Seed germination is affected by the presence of anthocyanin, but apparently only by the genotype of the mother at the anthocyanin locus, and not by the genotype of the embryo itself. In addition, there was an interaction between maternal morph and the maternal source population, with seeds from high-elevation anthocyanin-producing mothers germinating most rapidly and seeds from low-elevation anthocyanin-producing mothers germinating most slowly in a common garden at low elevation. However, because germination of anthocyanin-producing and anthocyaninless progeny proceed equally quickly, the anthocyanin marker provides unbiased estimates of outcrossing rates. The results overall support the use of anthocyanin as a neutral marker, with the alternate phenotypes unlikely to be differentially impacted by the processes of pollination, pollen-tube growth, and germination. Fluctuating selection on conditions for dormancy release may be partially responsible for the maintenance of the anthocyanin polymorphism in Datura stramonium.

Journal Article↗

Transcranial brain injuries caused by metal rods and pipes over the past 150 years.

Penetrating through and through (transcranial) injuries of the head and brain by foreign bodies other than bullet or shrapnel are extremely unusual. Although the case of Phineas Gage (1848) has been the most widely publicized, and stimulated much interest in brain function, additional surviving cases of through and through brain penetration by bars, rods or pipes have been reported. The author reviews 12 published cases over the last 150 years and describes two additional cases. The management of these cases is described. This group of patients for the most part experienced a functional outcome despite neurologic deficits.

Brain Injuries↗

Monitoring spinal cord motor and somatosensory evoked potentials in anesthetized primates.

Monitoring Motor Evoked Potential (MEP) to Transcranial Stimulation (TMS) monitoring (MEP) is a growing technique to assess motor function under anesthesia. The following primate study was conducted to analyze the non-myogenic spinal motor and sensory volleys and to examine their reproducibility under nitrous oxide-methohexidone anesthesia. The traveling periodic spinal descending MEP to TMS and ascending somatosensory (SEP) to posterior tibial nerve stimulation across the thoracic cord were recorded in 12 cynomolgus monkeys. Through a small T11-T12 laminotomy, an insulated stainless steel electrode was inserted into the epidural thoracic space. The potentials were analyzed under 50 vol% NO in O2 with methohexital (0.1-0.2 mg kg-1 min-1). A well-defined periodic TMS-MEPs and PTN-SEPs were recorded with high reproducibility and consistency in repeated trials under N2O-methohexital anesthesia. MEP tracing consisted of an initial peak (direct (D) wave), occurring at 2.43 (+/- 0.28) msec followed by subsequent five positive (indirect (I) waves). Spinal SEPs-MEPs were clearly defined, morphologically stable, and consistent over time under N2O-methohexitone anesthesia. The present primate study may set a model to monitor both modalities in anesthetized neurosurgical patients.

Anesthesia, General↗

Etomidate dose-response on somatosensory and transcranial magnetic induced spinal motor evoked potentials in primates.

There is growing interest and need to monitor reliably both motor (MEP) and somatosensory (SEP) evoked potentials under anesthesia. On a pre-established primate model, the present study examined the effect of incremental etomidate (ET) dosages on spinal neural MEPs to transcranial magnetic stimulation (TMS) and posterior tibial rate (PTN) SEPs. Through a small thoracic T11-T12 laminotomy, an insulated double bipolar electrode was inserted epidurally in seven cynomolgus monkeys. Spinal TMS-MEPs, PTN-SEPs, and frontal EEG were tested against graded increase of ET doses. Etomidate 0.5 mg kg-1 i.v. was initially given and followed by 30 min continuous infusion of 0.01 mg kg-1 min-1, 0.018, 0.032, 0.056, 0.1, and 0.18 mg kg-1 min-1 in that order. Measurable spinal MEPs and SEPs were recorded under deep ET anesthesia (total 12.38 mg kg-1 cumulative dose over 180 min). The EEG showed marked slow wave and graded burst suppression at cumulative dose of > or = 3.14 mg kg-1. The direct (D) and subsequent initial indirect (I) waves (I1, I2, I3) were reproducible at doses < 0.18 mg kg-1 min-1 infusion. The latter I-waves (I4 and I5) showed graded loss at infusion dosage 0.056 mg kg-1 min-1. Etomidate remains an anesthetic of attractive features in neuroanesthesia. In the primate model, neural MEPs-SEPs were reproducible despite the exceedingly high dose of ET and markedly depressed EEG. Moreover, MEP-SEP can be monitored during ET burst-suppressive neuroprotective state. The study may set a model in humans for intra-operative multi-modality neurophysiologic recording under ET-based anesthesia.

Animals↗

Sir Charles Ballance: pioneer British neurological surgeon.

Sir Charles A. Ballance (1856-1936) began his medical career at St. Thomas's Hospital the University College, London, England, in 1875, receiving honors in every subject and a gold medal in surgery. Victor Horsley (1857-1916) and Ballance were classmates at the University and in the later 1880s began work together at the Brown Institute and the National Hospital, Queen Square. In addition to important studies on vascular surgery, Ballance was involved in primate work on cerebral localization with lifelong friends Charles Beevor, Charles Sherrington, David Ferrier, and others. In June of 1887, Ballance assisted Horsley at Queen Square in the successful removal of an extramedullary spinal cord tumor. Horsley was about to abandon the operation, but his friend urged the removal of one lamina higher and the tumor was discovered. Ballance, a demonstrator in anatomy, realized the spinal cord segments lay higher in relation to the vertebral bodies than was generally appreciated. Ballance popularized the operation of radical mastoidectomy for advanced middle ear infection (1890), standardized an approach to drain or excise temporal brain abscesses, and was the first to clearly understand the neurological signs of cerebellar abscess (1894). Ballance also devised cranial base approaches to attack infectious thrombophlebitis of the lateral, petrosal, and cavernous sinuses. He was the first to completely remove an acoustic tumor (1894); 18 years later, the patient remained well. Ballance also drained a posterior fossa subdural hematoma (1906) and successfully sectioned the auditory nerve for Meniere's syndrome (1908). Ballance's operative experience with both supra- and infratentorial brain lesions included approximately 400 cases, which are detailed in his 1907 book, Some Points in the Surgery of the Brain and Its Membranes. His two-volume set, Essays on the Surgery of the Temporal Bone (1919), remains a brilliantly written and illustrated classic. Ballance was an expert on nerve regeneration and nerve grafting, and after many years of devoted research, he devised successful operations for facial nerve paralysis. For this and early vascular work, he is often credited as the first English surgeon to reintroduce classical Hunterian methods of experiment into surgery. He was honored as the founder and President of The Society of British Neurological Surgeons in 1926. Perhaps best known as a general and aural surgeon, Ballance was second only to Horsley in reputation as a pioneer British neurological surgeon. Described as a painstakingly slow but delicate and meticulous operator, Ballance made a contribution to neurosurgery and temporal bone surgery that was immense.

Brain Diseases↗

One hundred consecutive cases of selective termination of an abnormal fetus in a multifetal gestation.

OBJECTIVE: To determine whether transabdominal selective termination of one or more abnormal fetuses in a multifetal pregnancy with dichorionic placentation is a safe and effective procedure. METHODS: One hundred consecutive selective termination procedures were performed by transabdominal injection of potassium chloride into the heart or umbilical vein of an anomalous fetus in a multifetal pregnancy. All of the abnormal fetuses were presumed to have dichorionic diamniotic placentas, based on an ultrasound evaluation before the procedure. Follow-up data were obtained for each patient regarding the development of postprocedural complications, laboratory or clinical evidence of a coagulopathy, maternal or neonatal morbidity, gestational age at delivery, and birth weight of the infants. RESULTS: Ninety-one sets of twins were reduced to singletons, six sets of triplets were reduced to twins, two sets of triplets were reduced to singletons, and one set of quadruplets was reduced to triplets. The anomalous fetus or fetuses were identified correctly and terminated in each case. Three patients spontaneously aborted, and one women electively terminated her pregnancy 2 weeks after the procedure. The mean gestational age at delivery of the 96 patients who delivered surviving infants was 36.8 weeks, and 85.4% delivered at 32 weeks or later. Three women developed laboratory evidence of a coagulopathy, but there were no cases of clinically evident disseminated intravascular coagulation. CONCLUSION: This procedure, performed at a single institution by a small number of operators using a common protocol, accomplished its objective in all cases, was accompanied by a low spontaneous loss rate, and resulted in the birth of healthy infants at or near term in the vast majority of cases. This series suggests that selective termination is a reasonable option to consider when one abnormal fetus is found in a multifetal pregnancy with dichorionic placentation.

Abortion, Eugenic↗

Benjamin Winslow Dudley and early American trephination for posttraumatic epilepsy.

Benjamin Winslow Dudley (1785-1870) was a Kentucky frontier surgeon who received basic medical education in the United States and extensive surgical training in Europe. He returned to Lexington to become a dominant figure and the most prominent surgical teacher in the Mississippi Valley. Written evidence of Dudley's operative accomplishments are sparse, but he seems to have combined the finest French (Dominique Jean Larrey, Guillaume Dupuytren) and British (Henry Cline, John Abernethy, Astley Cooper) surgical training with conservative and thoughtful patient selection. His operative endeavors in the preantiseptic era included trephination for posttraumatic epilepsy in six patients (1819-1832). This was the largest recorded series of such cases, and it stimulated other American surgeons to trephine for relief of posttraumatic seizures. Trephination for decompression and debridement was undertaken at the site of original injury to remove the cause of "cerebral excitement" and restore "corporeal and intellectual function." Dudley considered this a safe operation in "cautious, firm, and intelligent hands." He thought crowded urban hospitals were unsafe and attributed his better surgical results to the clean, rural Kentucky air. Dudley's achievement is contrasted with other Early American preantiseptic trephinations for posttraumatic epilepsy.

Epilepsy, Post-Traumatic↗

Hepatobiliary excretion of bile acids and rose bengal in streptozotocin-induced and genetic diabetic rats.

Divergent opinions regarding the effect of streptozotocin- (STZ) induced diabetes on bile flow rate may be due to the differing lengths of time after STZ administration at which bile flow was measured. Also, the biliary excretion of bile acids can influence the canalicular transport of several organic anions. Therefore, the hepatic clearance of the bile acid-dependent organic anion rose bengal was studied over a 30-day period in STZ-induced insulin-dependent Sprague-Dawley diabetic rats with elevated bile acid pools and in fatty noninsulin-dependent diabetic and lean Wistar rats. Excretion of total bile acids and rose bengal was higher in diabetic rats than in Sprague-Dawley control or lean or fatty Wistar rats. Depletion of bile acids for 10 hr in the 30-day STZ rat prevented the increased excretion of rose bengal. Bile flow rates in fatty and lean Wistar rats were similar to that in Sprague-Dawley controls. Increased bile acid excretion 7 and 14 days after STZ was not accompanied by the expected significant increase in bile flow, reflecting decreased bile acid-independent bile flow, regardless of method of calculation of bile flow (per g liver or per kg body weight). By 30 days, there were significant increases in bile acid excretion and bile flow. The increased clearance of rose bengal 7 days after STZ indicates that pathophysiological changes in the hepatocyte begin soon after the initiation of diabetes. Studies of taurocholate uptake into liver plasma membrane vesicles indicated that the maximal velocity of transport across the basolateral membrane was increased with no change in Km. This change was not observed in vesicles from insulin-treated diabetic rats. Therefore, studies employing STZ need to allow time for STZ toxicity to be overcome and for the pathology of diabetes to become established, to accurately reflect the diabetic condition.

Adenosine Triphosphate↗

Civilian cases of tangential gunshot wounds to the head.

A series of 168 civilian cases of tangential gunshot wounds to the head is presented. Neurologic deficits on presentation were generally minimal. Computed tomographic (CT) scans were performed in 51% of patients, and abnormal CT findings were noted in 35% (18% of all patients). Major operative procedures were required in 9% of the patients. Serious sequelae of tangential injuries are described even with patients who initially have no neurologic abnormality. We suggest that a CT scan is warranted in all cases of tangential gunshot wounds to the head.

Adolescent↗