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J Reif

Publications and source records attributed to J Reif.

At least 19 recordsLinked to original sources
PubMed1999

Micro flow bio-molecular computation.

In this paper we provide a model for micro-flow based bio-molecular computation (MF-BMC). It provides an abstraction for the design of algorithms which account for the constraints of the model. Our MF-BMC model uses abstractions of both the recombinant DNA (RDNA) technology as well as of the micro-flow technology and takes into account both of their limitations. For example, when considering the efficiency of the recombinant DNA operation of annealing, we take into account the limitation imposed by the concentration of the reactants. The fabrication technology used to construct MEMS is limited to constructing relatively thin 3D structures. We abstract this by limiting the model to a small constant number of layers (as is done with VLSI models). Besides our contribution of the MF-BMC model, the paper contains two other classes of results. The main result is the volume and time efficient algorithm for message routing in the MF-BMC model, specifically useful for PA-Match. We will show that routing of strands between chambers will occur in time O(N x D/ m x n), where N is the number of strands in the MF-BMC, n is the number of chambers where RDNA operations are occurring, D is the diameter of the topology of the layout of the chambers, and m is proportional to the channel width. Operations that need annealing, such as PA-Match, are shown feasible in O(N2logN/n/n) volume instead of the previous use of omega(N2) volume, with reasonable time constraints. Applications of the volume efficient algorithm include the use of the Join operation for databases, logarithmic depth solutions to SAT (Boolean formula satisfiability) problems and parallel algorithms that execute on a PRAM. Existent algorithms can be mapped to ones that work efficiently in the MF-BMC model, whereas previous methods for applications such as PRAM simulation in BMC were not both time and volume efficient. Our other class of results are theoretical lower bounds on the quantities of DNA and the time needed to solve a problem in the MF-BMC model, analogous to lower bounds in VLSI. We bound the product BT from below, and further show that BT2 has a stronger lower bound of I2. Here B is the maximum amount of information encoded in the MF-BMC system at a time. T is the time for an algorithm to complete, and I is the information content of a problem.

Animals↗
PubMed1998

Workshop report. Health risks of drinking water chlorination by-products: report of an expert working group.

Studies of water chlorination by-products have suggested a possible increased risk of bladder and colon cancers, as well as adverse reproductive and developmental effects such as increased spontaneous abortion rates and fetal anomalies. A workshop for an expert working group was convened to advise Health Canada on the need for further action. Participants were given background papers and a set of key questions to review prior to the meeting. At the workshop, experts presented an overview of what was known to date on water chlorination by-products from toxicologic studies, epidemiologic studies of cancer and adverse reproductive/developmental effects, and risk assessment. This paper summarizes the information provided in the background papers and presentations, describes the consensus arrived at regarding assessment of evidence for level of risk and presents a number of suggestions for future research.

Abnormalities, Drug-Induced↗
PubMed1995

Microsurgery of cerebral lesions under stereotactic conditions.

Microsurgical excision of cerebral lesions was carried out under CT-guided stereotactic conditions. For lesions located in critical cortical areas, cerebral teleangiography under stereotactic conditions provided the coordinates of the vascular elements related to the structures and adjacent to the lesion without X-ray distortion. Small size cortical and subcortical lesions were targeted using the stereotactic biopsy probe as a guide. In twenty-four patients stereotactic microsurgery was used for following lesions: 8 cavernomas, 8 metastases, 7 gliomas, and 1 tuberculoma. Unpredictable permanent neurological complications did not occur, but predicted transient impairment after surgery in functional territories was tolerated with the complete removal of the lesion. The advantages of microsurgery using stereotactic coordinates are: precise knowledge of the location of brain structures and exact targeting of intracerebral lesions, better evaluation of surgical risks, easy spatial orientation, and minimization of the surgical damage to the healthy brain tissue.

Adolescent↗
PubMed1995

Polysyndactyly and asymptomatic hypothalamic hamartoma in mother and son: a variant of Pallister-Hall syndrome.

We report on a 53-year-old woman and her 20-year-old son who both presented with polysndactyly, without other external malformations or mental retardation. MRI imaging revealed, as an incidental finding, asymptomatic hypothalamic hamartomas in both patients. The siblings of both mother and son are unaffected. This family may represent an autosomal dominant variant of Pallister-Hall syndrome.

Abnormalities, Multiple↗
PubMed1994

Modulated surgery in the management of ruptured intracranial aneurysm in poor grade patients.

The treatment of subarachnoid haemorrhage caused by aneurysm in comatose patients with or without midbrain symptoms is a matter of controversy. The question is, which comatose patients will profit from aneurysm surgery and which will not? In a retrospective study, 573 patients were examined between 1986 and 1992. Of these, 116 were in poor condition (Hunt and Hess Grade IV or V). The following management protocol was used: after computer tomography, a decision was made whether intensive medical treatment was performed or not. The reason for not operating was essentially the severity of the cerebral haemorrhage and poor or absent intracranial filling on angiography. Extracerebral causes were renal failure, sepsis, liver cirrhosis and pulmonary embolism. The direct early aneurysm operation was performed in the clinical deterioration phase in patients with space-occupying haematomas. In dilatation of the ventricle system, external drainage was initially positioned, in the case of bilateral haematocephalus, two-sided drainage was positioned, then intensive medical treatment and angiography were performed. The aneurysm operation was then ruled out if there was no clinical improvement. Aneurysm operation was performed on 57 of the 116 patients; 13 died, 32 showed a good and 12 a poor or fair outcome. 15 patients had mid-brain syndrome, and 5 of them died. Based on our experience, we draw the following conclusion: the Hunt and Hess scale alone is not a sufficient basis for decision taking. Some of the comatose patients, even in mid-brain syndrome, profit from an early operation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Intraventricular haemorrhage caused by aneurysms and angiomas.

More than 200 intraventricular haematomas (IVH) have been treated in the Homburg Neurosurgical University Clinic since computed tomography was available and facilitated the diagnosis. Among 200 consecutive cases, which are analysed and presented in this publication, there were 71 patients with subarachnoid haemorrhage (SAH)--58 of whom with angiographically and/or pathologically verified aneurysms--, and 21 cases with intraventricular angiomas. IVH without concomitant intracerebral haematoma (ICH) and without evidence of SAH is highly suggestive of intraventricular angioma. In our experience panangiography [if available digital subtraction angiography (DAS)] should be done as soon as possible in all cases of IVH. It is a precondition for early diagnosis and operative elimination of the source of bleeding, because the retrospective analysis of our material shows that rebleeding is by far the highest single risk factor in cases with IVH caused by aneurysms or angiomas. We therefore recommend early microsurgical occlusion of the aneurysms and exstirpation or intravascular embolisation of the angioma. The best survival rate (76%) was achieved in IVH cases caused by angiomas. In aneurysms with IVH the survival rate was 35%, in IVH caused by other diseases 37%. The worst prognosis occurs in SAH with IVH without proven aneurysm or angioma. The survival rate of this group was only 8%.

Adolescent↗
PubMed1992

Inadvertent intracranial placement of a Foley catheter. A rare iatrogenic complication of severe frontomaxillary trauma.

Severe comminuted fractures of the facial bones involving the cranial base are often accompanied by heavy bleeding into the nasopharynx. This presents considerable problems in primary care both for the anesthesiologist and the surgeon. Such bleeding can be controlled by Bellocq tamponade or using a Foley inflatable catheter. Skull base fractures may involve the risk of the catheter inadvertently penetrating into the brain. The authors describe a case in which a misguided Foley catheter, which was blindly inserted through the nose in an attempt to tampon the nasopharynx, resulted in fatal cerebral damage.

Adult↗
PubMed1990

Selective monitoring of patients with suspected blunt cardiac injury.

Blunt chest trauma can result in cardiac injury with consequent dysrhythmias, valve malfunction, or frank rupture. Typically, patients with blunt chest trauma and suspected cardiac injury have required cardiac monitoring for 48 to 72 hours. Predicting which patients with blunt chest trauma are not at risk for cardiac complications would obviate many patient-hours of monitoring in the intensive care unit. This series examines the sensitivity of two-dimensional surface echocardiography in predicting cardiac complications. Over a 24-month period, 115 patients were admitted with blunt chest trauma and prospectively evaluated for cardiac injury with admission electrocardiograms, serial creatine kinase isoenzyme studies, and two-dimensional echocardiography. Thirty-one patients (27%) had abnormal two-dimensional echocardiograms. In 8 (25.8%) of these patients, cardiac complications requiring treatment developed. Eighty-four patients (73%) had normal two-dimensional echocardiograms, and a cardiac complication requiring treatment developed in only 1 (1.2%) of them. Of the 9 patients who required treatment of cardiac complications, 3 had normal admission electrocardiograms and only 1 had elevated levels of the myocardial-specific isoenzymes of creatine kinase. We believe two-dimensional echocardiography is a sensitive test for evaluating cardiac injury resulting from blunt chest trauma and is helpful in selecting those patients who require monitoring in the intensive care unit.

Adult↗