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Biomedical subjects

H Gill

Publications and source records attributed to H Gill.

At least 37 records · Page 2Linked to original sources
PubMed1998

Perceived symptoms amongst hypertensive patients in routine clinical practice- a population-based study.

OBJECTIVES: To compare perceived symptoms between patients undergoing antihypertensive therapy and hypertensive patients without drug treatment, and to assess reasons for change of antihypertensive medication in routine clinical practice. DESIGN: Population-based multicentre study. Consecutive patients from a randomized sample of centres were given a standardized questionnaire to assess symptoms as well as opinions about their antihypertensive drugs. SETTING: Fifty-five Swedish primary health care centres and 11 clinics of internal medicine. PATIENTS: One thousand and thirteen hypertensive patients on their individually prescribed antihypertensive medication and 13 5 without antihypertensive therapy. MAIN OUTCOME MEASURES: Prevalence and perception of symptoms with and without antihypertensive drug therapy, changes of medication and reasons for this. RESULTS: Amongst the group of patients on antihypertensive medication, 57% spontaneously reported having had symptoms of high blood pressure before they started their drug therapy. Amongst the patients without antihypertensive drugs, 52% reported having such symptoms. When answering direct questions about different symptoms related to current drug treatment or increased blood pressure, patients with and without medication reported symptoms to a similar extent: 80 and 85%, respectively. A majority of patients (64%) had changed their medication during the course of treatment (range 0-61 years). The mean number of changes was 2.4 times over 12 years. The most common reported cause for changing drug treatment was side-effects (42%). CONCLUSIONS: The study shows that patients in general perceive symptoms from hypertension. Antihypertensive medication decreases the frequency and intensity of symptoms that might be related to high blood pressure but adds other symptoms linked to the medication. Changes in medication were mostly related to side-effects. The follow-up should pay attention to patients' experience of treatment. A sign of a well-managed hypertension population would be a decrease of symptoms over time.

Adult↗
PubMed1998

Histological and clinical findings in 896 consecutive prostates treated only with radical retropubic prostatectomy: epidemiologic significance of annual changes.

PURPOSE: Recognizing that the unprecedented increase in new cases of prostate cancer between 1988 and 1996 actually peaked in 1992 and has now returned to baseline, we examined our clinical and histological database for annual trends in 896 consecutive men treated only with radical prostatectomy for clinical stages T1c to T2c from 1988 to 1996. MATERIALS AND METHODS: All radical prostatectomy specimens were examined prospectively in 3 mm. step sections by 1 pathologist. Using multiple logistic regression for dichotomous variables and multiple linear regression for continuous variables, both corrected for age, we assessed the annual trends for significant changes in T1c versus T2 clinical stages, preoperative serum prostate specific antigen (PSA), cancer volume, percent Gleason grade 4/5 in the cancer, location of the cancer in the transition or peripheral zone, organ confined status, seminal vesicle invasion, positive surgical margins, prostate weight and presence of clinically insignificant cancers (less than 0.5 cc in volume). RESULTS: There were no significant annual changes in the proportion of percent Gleason grade 4/5 cancer, serum PSA, prostate weight or clinically insignificant cancers less than 0.5 cc, and the annual changes for cancer volume were only of moderate significance. T1c cancers increased from 10% in 1988 to 73% in 1996 (p=0.0001), organ confined cancers from 40 to 75% (p=0.0001) and transition zone cancers from 10 to 21% (p=0.003). Seminal vesicle invasion decreased from 18 to 5% (p=0.001) and positive surgical margins from 30 to 14 (p=0.006). Mean patient age changed from 65 to 62 years (p=0.0001). CONCLUSIONS: We believe that the extraordinary rise and fall in prostate cancer detection rates from 1990 to 1994 primarily removed previously undetected T2 cancers from the pool at large, leaving impalpable T1c cancers as the primary reservoir of prostate cancers in the United States. Importantly, cancer volume, percent Gleason grade 4/5 cancer, serum PSA and cancers less than 0.5 cc have not had a highly significant change during these critical 9 years. These data argue strongly that current PSA testing has not resulted in the detection of clinically insignificant cancers, and that PSA screening should be expanded and not restricted.

Age Distribution↗
PubMed1998

Dynamic positron emission tomography with F-18 fluorodeoxyglucose imaging in differentiation of benign from malignant lung/mediastinal lesions.

PURPOSE: This study was done to evaluate the diagnostic utility of dynamic positron emission tomography (PET) with F-18 fluorodeoxyglucose (FDG) imaging in patients with suspected malignant pulmonary lesions. We wanted to test the hypothesis that the rate of FDG uptake (FDG influx constant values) would differentiate malignant from benign lung or mediastinal lesions. MATERIALS AND METHODS: We performed segmental dynamic PET imaging studies following administration of FDG in 19 patients with indeterminate pulmonary lesions based on chest radiograph and/or CT scans. Patlak analysis was done to compute Ki (FDG influx constant) values and compared with FDG standardized uptake values (SUVs) and histology. RESULTS: FDG Ki values (mean+/-SD) were significantly greater (p < 0.01) in all 12 malignant lesions (0.029+/-0.02) as compared with 7 benign lesions (0.0024+/-0.0011) with good correlation to the SUV values. Distinct time activity curve patterns were identified in malignant and benign lesions with continued uptake in malignant lesions. CONCLUSION: Dynamic PET-FDG imaging accurately differentiates malignant from benign pulmonary lesions. In certain cases with equivocal findings on visual analysis and SUV values, dynamic imaging may be further helpful in differentiating benign and malignant lesions.

Adenocarcinoma↗
PubMed1998

Patients' and physicians' assessment of risks associated with hypertension and benefits from treatment.

BACKGROUND: Perceptions of effects of a medical regimen may affect patients' adherence to therapy. OBJECTIVE: To assess concordance between patients' and physicians' estimations of the risks of hypertension and benefits of treatment during a regular follow-up appointment. DESIGN: A population-based Swedish multicentre study. Patients were included consecutively from a randomized selection of centres (55 primary health care centres and 11 clinics of internal medicine). METHODS: A questionnaire was given to 1013 patients undergoing their individually prescribed antihypertensive therapy and 212 physicians who were caring for these patients. RESULTS: Without therapy, patients perceived the risks of cardiovascular complications to be higher than did their physicians. Patients were not aware that an increasing number of risk factors has an impact on the risk of complications. Patients furthermore rated the benefits of treatment higher than did their physicians (P<0.001). Of the patients, 14% had blood pressures < or = 140/90 mmHg. Most of the patients (61%) were not aware of their target blood pressure. However, when the target pressure was communicated to patients by the physician, patients remembered it accurately. The patients were generally not willing to trade even minor side effects from antihypertensive therapy for benefits of treatment. CONCLUSIONS: There was a high degree of inconsistency between patients' and physicians' estimations of risks of hypertension. Patients estimated the effects of treatment to be more beneficial than did their physicians.

Adult↗
PubMed1997

Extended telemedical consultation using Arden Syntax based decision support, hypertext and WWW technique.

There is an obvious need for geographic distribution of expert knowledge among several health care units without increasing the cost of on-site expertise in locations where health care is provided. This paper describes the design of a knowledge-based decision-support system for extended consultation in clinical medicine. The system is based on Arden Syntax for Medical Logic Modules and hypertext using World Wide Web technology. It provides advice and explanations regarding the given advice. The explanations are presented in a hypertext format allowing the user to browse related information and to verify the relevance of the given advice. The system is intended to be used in a closed local network. With special precautions regarding issues of safety and patient security, the system can be used over wider areas such as in rural medicine. A prototype has been developed in the field of clinical microbiology and infectious diseases regarding infective endocarditis.

Artificial Intelligence↗
PubMed1995

Evaluation of a knowledge-based decision-support system for ventilator therapy management.

Evaluation of knowledge-based systems differs from that of conventional systems in terms of verification and validation techniques. Furthermore, evaluating medical decision-support systems is difficult because the field is thus far comparatively unexplored. This paper presents an evaluation of a medical knowledge-based system called VentEx that supports decision-making in the management of ventilator therapy. Real patient data from 1300 hours of patient care involving 12 patients with 6 diagnoses are used to validate the knowledge base. The results range from 4.5% to 15.6% disagreement between the setting recommendations produced by VentEx and a gold standard, and 22.2% disagreement for recommendations for weaning. A comparison between the standard and two physicians showed that VentEx produced advice of the same quality as the physicians.

Databases, Factual↗
PubMed1995

The human MLL gene: nucleotide sequence, homology to the Drosophila trx zinc-finger domain, and alternative splicing.

We have previously reported the cloning of several cDNAs corresponding to the MLL gene. The predicted primary amino acid sequence of two of these clones, 14p-18B and 14-7, reveals nearly complete identity with parts of the sequences of HRX, ALL-1, and Htrx-1, including a Zinc-finger region with homology to the Drosophila trithorax gene. However, we found that there is a stretch of 39 amino acids that is absent from 14p-18B when compared to ALL-1 and HRX. Another sequence of three amino acids is present in ALL-1, but is absent from 14p-18B and HRX. Nucleotide sequence examination reveals that these differences arise from alternative splicing, suggesting that MLL, HRX, and ALL-1 each represents a different alternative splicing product from the same gene. At least two cDNA clones, 14-7 and 14p-18C, correspond to incompletely processed transcripts including intron sequences. Northern blots using a subclone of 14p-18B revealed mRNA species of 14-16 kb in size in various human tissues. RNase protection assays show that the splice variant containing exon 8 and lacking a 9-bp extension 3' of exon 12 is predominantly expressed in hematopoietic cell lines.

Alternative Splicing↗
PubMed1995

Arden syntax and GALEN terminology support: a powerful combination to represent medical knowledge.

Arden syntax is an ASTM standard defined a few years ago to represent rule-based knowledge in the medical domain in an application- and implementation-independent way. Knowledge is expressed as Medical Logic Modules (MLMs). So far, it has mainly been used for providing critique and reminders in data driven, medical decision support systems, where typically rules are evoked by certain database operations (e.g., "store systolic blood pressure"). The syntax is an important step towards a general medical knowledge representation, with version control, maintenance information, arithmetic operations, logic rule syntax, and temporal operations, but it is not yet complete. The standard does not define how medical concepts (e.g., "systolic blood pressure") are to be referenced. Existing coding schemes such as SNOMED and ICD10 may be used for this, but they have generally failed to provide the required level of detail. The use of Arden syntax to transfer knowledge between centers in the form of MLMs has been shown to be non-trivial [1,2]. GALEN (Generalized Architecture for Languages, Encyclopedias, and Nomenclatures in Medicine) is an EC AIM project aiming at a machine-readable system to represent medical concepts in a semantic network. The network allows for the combination and specialization of concepts to the required level of detail. The project has resulted in a notation (GRAIL: GALEN Representation and Integration Language) and several tools, such as browsers for manipulating medical concepts. In a GALEN subproject, we are exploring the potential utility of combining Arden syntax with semantics from the GALEN terminology, and we are developing tools to facilitate the creation of MLMs with terminology support. Our impression is that the combination is very useful: GALEN tools allow a domain expert to express her knowledge in purely medical terms, independent of an actual or intended patient database structure and data representation. They can also help a knowledge engineer or quite possibly an automatic interpreter to translate a well defined medical concept (expressed in GRAIL) to actual database queries (in SQL or other notation). This translation can be facilitated by a Data Dictionary describing the local patient database.

Expert Systems↗
PubMed1994

DNA rearrangements and altered transcripts of the MLL gene in a human T-ALL cell line Karpas 45 with a t(X;11) (q13;q23) translocation.

Translocations involving chromosome band 11q23 are found in both lymphoid and myeloid leukemias as well as in lymphomas, in these translocations. The chromosomes most frequently involved in reciprocal translocations include chromosomes 4, 6, 9, and 19, and we and others have reported that chromosomes 1, 2, 10, 15, 17, 18, 22, and X are also involved. In the cell line Karpas 45, which has a t(X;11) (q13;q23) translocation, we report here that the MLL gene is rearranged and that there are two altered transcripts of MLL that come from the der(11) chromosome.

Chromosomes, Human, Pair 11↗
PubMed1993

A t(11;12) 11q23 leukemic breakpoint that disrupts the MLL gene.

Translocations involving 11q23 have been shown to be a consistent finding in human hematopoietic malignancies and in some constitutional abnormalities. The identification of a gene, MLL (myeloid/lymphoid or mixed-lineage leukemia), that spans the breakpoints in four different recurrent 11q23 translocations was recently reported. We describe a rare (11;12)(q23;p13) translocation, observed in leukemic cells from a patient with acute lymphoblastic leukemia, which also disrupts this gene.

Blotting, Southern↗
PubMed1993

Functional and urodynamic characteristics of an ileal neobladder.

We examined the urodynamic characteristics and symptoms of 28 patients who had undergone the Stanford pouch bladder substitution following cystoprostatectomy. Urodynamics were obtained a mean of 18 months (range 6 to 43) after construction of the neobladder. Mean cystometric capacity was 699 cc (range 366 to 1,370). All patients voided by the Valsalva maneuver and achieved good peak flow rates (mean 19 cc per second). Of the patients 23 emptied to near completion with a mean post-void residual of 34 cc, while 5 had post-void residuals of greater than 150 cc (mean 630 cc). The neobladders demonstrated good compliance for the storage of urine, with a mean basal pressure of less than 15 cm. water at volumes of less than 500 cc at which most bladders function, and of 22.4 cm. water (range 1 to 72) at 100% capacity. Phasic neobladder contractions were present during filling cystometrography. While the number increased at higher neobladder volumes, the mean length and mean pressure did not. The mean pressure of contractions was less than 40 cm. water at lower and higher volumes. Daytime continence was attained in 26 of 28 patients (93%), while 17 (61%) attained nighttime continence. Of these 17 patients 14 (82%) had to void at least once at night to stay dry. Daytime incontinent patients had decreased neobladder compliance at high volumes compared to daytime continent patients (p < 0.05) but there was no difference in the maximal urethral closure pressure or the pressure of phasic contractions between these 2 groups. No difference was found in any urodynamic parameter between nighttime continent and incontinent patients. Patients with poor emptying ability (defined as a post-void residual of more than 150 cc) had increased neobladder compliance relative to patients with good emptying ability, as well as a statistically significant increased capacity (1,067 cc versus 623 cc). There was no difference in any important urodynamic parameter between patients who had and had not received postoperative chemotherapy. We conclude that a neobladder constructed from detubularized ileum achieves adequate capacity at low pressures with a satisfactory continence rate. Most patients empty the bladder to completion by Valsalva's maneuver. Low compliance at high volumes appears to be a factor in daytime incontinence.

Adult↗
PubMed1991

Multivariable optimization of mechanical ventilation. A linear programming approach.

The proposed method aims at improved ventilatory care with reduced morbidity. It combines two important aspects of mechanical ventilation: gas exchange and lung mechanics. A single criterion was selected as optimization index of lung trauma: peak respiratory power (PRP) defined as the maximum product of pressure times flow during inspiration. Arterial blood gases reflect gas exchange and constitute the constraints of the problem. The constraints as well as the optimization index are expressed as linear functions of the input variables (frequency of breathing, tidal volume, and positive end expiratory pressure). A linear programming approach can therefore be used to determine the values of input variables that minimize PRP and at the same time keep arterial blood gases within the prescribed limits. The coefficients of the constraints and the optimization index equation are found by manipulating input variables in order to obtain four different values of PaO2, PaCO2 and PRP (there are four coefficients in each equation). The coefficients can then be calculated and the optimization procedure run. In a pilot study 5 patients suffering from diseases of varying pulmonary pathology were investigated with this method. In 4 out of 5 the ventilator treatment improved in terms of blood gas values (mean increase in PaO2 was 4.7%) and reduction of mechanical load on the lungs (mean PRP reduction was 20%). Lower PRP is accompanied by lower mean power and pressure values, which results in increased cardiac output. Presently, the main problem is the time it takes to determine the patient coefficients (approx one hour), a procedure that needs to be simplified.

Acute Disease↗
PubMed1991

Medical logic module (MLM) representation of knowledge in a ventilator treatment advisory system.

In any medical expert system it is the inherent knowledge that is the power of the system and not the particulars of its implementation. Therefore it would be valuable to use a representation that would allow: knowledge transfer between different systems, users, experts and 'importers' to be able to evaluate the logic, experts to easily input their knowledge and be guided how to use the syntax. Adren Syntax of Medical Logic Module is a proposed knowledge representation, fulfilling these criteria. The Arden Syntax has been used to represent rules and logic in a decision support system for ventilator therapy in patients with acute respiratory failure (ARF) that is under development. The medical experts involved in the project have used the Arden Syntax as a convenient way for transfer and storage of medical knowledge. The syntax is easy to learn and may be used with a minimum of training. In the present system, Medical Logical Modules have been used to represent knowledge pertinent to the initiation and maintenance phases of ventilator therapy.

Acute Disease↗
PubMed1990

Integrating knowledge-based technology into computer aided ventilation systems.

A knowledge-based decision support system for respirator treatment, the KUSIVAR system, has been designed in cooperation between hospital, university and industry. Changes in patient data from respirator and monitoring equipment trigger a computer program that generates advice to the staff concerning e.g. therapy modes and respirator settings using expert systems and process control technology. A prototype has been built on an advanced development workstation, the Unisys Explorer, using the software Knowledge Engineering Environment (KEE). The clinical version is implemented on an Intel 80396-based microcomputer connected on-line via a data-acquisition processor to the respirator. The decision support software is implemented as a module under the Microsoft Windows multitasking environment and communicates with modules for data acquisition, database handling and data presentation by means of message passing using the Windows Dynamic Data Exchange protocol. The modules present coherent user interfaces by conforming to Microsoft Windows standards. The knowledge base is being extensively validated by an expert group in the ICU and the system will be evaluated through animal experiments and clinical studies.

Computer Systems↗
PubMed1989

Knowledge base design for decision support in respirator therapy.

A knowledge base is built for decision support applied to respirator therapy (the KUSIVAR project). The knowledge representation is object-oriented using frames to store multiple forms of knowledge: variable descriptions, transformation tables, rules and mathematical models. The system is data-driven, generating and displaying advice automatically triggered by changes in data from the respirator and the patient. The inferenceing mechanism is forward-chaining i.e. a rule is evaluated as soon as it's condition is satisfied. Temporal aspects of the reasoning are represented by a number of mechanisms, among others limited validity times for data, trend analysis and mathematical models. The knowledge base is organized according to disease groups and decision situation which simplifies knowledge acquisition and improves response times since it enables the system to focus on a limited set of rules in each situation. To test the feasibility of the system design a prototype has been built using Knowledge Engineering Environment (KEE) from Intellicorp on an Explorer workstation from Unisys. The production system, which is interfaced to a Siemens Elema Servo Ventilator 900C, is currently being implemented under the Microsoft Windows multitasking environment on a microcomputer based on an Intel 80386 processor.

Decision Support Techniques↗
PubMed1989

A knowledge-based support system for mechanical ventilation of the lungs. The KUSIVAR concept and prototype.

The KUSIVAR is an expert system for mechanical ventilation of adult patients suffering from respiratory insufficiency. Its main objective is to provide guidance in respirator management. The knowledge base includes both qualitative, rule-based knowledge and quantitative knowledge expressed in the form of mathematical models (expert control) which is used for prediction of arterial gas tensions and optimization purposes. The system is data driven and uses a forward chaining mechanism for rule invocation. The interaction with the user will be performed in advisory, critiquing, semi-automatic and automatic modes. The system is at present in an advanced prototype stage. Prototyping is performed using KEE (Knowledge Engineering Environment) on a Sperry Explorer workstation. For further development and clinical use the expert system will be downloaded to an advanced PC. The system is intended to support therapy with a Siemens-Elema Servoventilator 900 C.

Adult↗