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J R Monson

Publications and source records attributed to J R Monson.

134 records · Page 8Linked to original sources
PubMed1982

Renal accumulation of ammonia: the cause of post-ischaemic functional loss and the "blue line".

The "blue line", a dark discoloration at the corticomedullary junction, is a constant finding after a significant period of renal ischaemia. In this study, it has been shown to be caused by packing of all of the peritubular capillaries at the corticomedullary junction with red blood cells. Five rats and 10 dogs were alkalinised by replacing their drinking water with 2% sodium bicarbonate for 2 weeks pre-operatively, in order to inhibit the glutaminase enzyme system and thereby decrease ammonia accumulation during ischaemia. Five rats and 6 dogs were used as unprotected controls. All animals were subjected to 60 min warm ischaemia. Renal function was significantly protected in the alkalinised rats (P less than 0.002) and dogs (P less than 0.001), with the serum creatinine rising to a maximum of 0.21 +/- 0.03 mmol/l in the alkalinised rats and 0.18 +/- 0.04 mmol/l in the alkalinised dogs. There was no "blue line" in the alkalinised animals. It is suggested that the "blue line" plays a central role in post-ischaemic renal failure. Prevention of ammonia formation by alkalinisation protects against ischaemic renal damage and the formation of the "blue line".

Ammonia↗
PubMed1978

A national study of medical and surgical specialties. II. Description of the survey instrument.

The survey instrument used in the national study of physician activities conducted by the University of Southern California, Division of Research in Medical Education, is a log-diary in which physicians kept a record of their actual professional activities. The log-diary focused on use of physician time and patient encounters and employed numerical coding of activities and patient encounters in a highly structured format. Compared with instruments used in similar studies, this log-diary appears to gather a greater breadth and depth of information about physician practice patterns.

California↗
PubMedDate not supplied

Microvessel density of invasive breast cancer assessed by dynamic Gd-DTPA enhanced MRI.

It has been postulated that the rapid enhancement demonstrated by breast carcinomas after administration of contrast media is a direct result of tumor angiogenesis. However, to date, little quantitative data have been published to support this view. A retrospective study has been undertaken to compare dynamic contrast-enhanced data obtained from 40 patients with microvessel density (MVD) evaluated in specimens immunohistochemically stained with a factor VIII related antigen. The dynamic data were analyzed quantitatively using both simple indices of enhancement and a two-compartment kinetic model. A moderate but significant correlation was demonstrated between initial enhancement and MVD, and this correlation strengthened when node-positive tumors were considered in isolation (r = .77, P < .0005). However, the data showed considerable variability. The enhancement characteristics of the tumors could not be explained solely by their MVD; therefore, MRI cannot be used to predict MVD in vivo. Further work is required to address the exact relationship between contrast-enhanced MRI and tumor angiogenesis.

Adult↗
PubMedDate not supplied

Routine screening for local recurrence following breast-conserving therapy for cancer with dynamic contrast-enhanced magnetic resonance imaging of the breast.

BACKGROUND: Dynamic contrast-enhanced magnetic resonance imaging (MRI) of the breast is highly sensitive for the diagnosis of primary breast malignancy. We investigated the clinical application of dedicated dynamic breast MR for routine screening for local recurrence following breast-conserving therapy. METHODS: Patients underwent a single dynamic MR of the breast routinely in the period 1 to 2 years following treatment, or earlier if recurrence was suspected. A biopsy was performed if there was suspicion of recurrence on MR. RESULTS: One hundred and five patients with a median age of 58 years (range 50 to 65 years) were recruited for the study. Sixteen biopsies were performed and nine recurrences were confirmed histologically. Patients not undergoing biopsy have been followed up for a median of 341 days (range 168 to 451 days) following the MR. The sensitivity for clinical examination, mammography, examination combined with mammography, and MRI alone for the detection of recurrent cancer were 89%, 67%, 100%, and 100%, respectively, and the specificity was 76%, 85%, 67%, and 93%. CONCLUSION: Combined clinical examination and mammography are as sensitive as dedicated dynamic MR of the breast for the detection of locoregional recurrence, but breast MRI is associated with a far greater specificity. Therefore, dedicated dynamic breast MRI should be used when there is clinical or mammographic suspicion of recurrence to confirm or refute its presence.

Aftercare↗
PubMedDate not supplied

Prognostic factors: guidelines for investigation design and state of the art analytical methods.

The proliferation of putative prognostic factors, derived prognostic indices and computerised prediction of outcome in surgical oncology has led to some confusion over the exact methods available for deriving clinically significant prognostic factors. The realisation that the interaction between factors is often complex and non-linear has led to the development of new statistical techniques. The aim of this article is to review the currently available methods of analysis. A review of the relevant literature available from statistical, medical and computer science sources was performed. Information has been conveyed at a level aimed at producing a practical understanding of the techniques involved rather than their underlying mathematical basis. There are now clear guidelines for the investigation of putative prognostic factors (Table 1). The established role of linear statistical models and prognostic indices remains vitally important for the majority of diseases with many derived prognostic indices having been validated in a prospective fashion. However, in order to improve the delineation of prognostic factors other more complex methods of analysis are now being utilised. Furthermore, the recognition of complex dynamic non-linearity within biological systems has led to the increasing use of non-linear statistical techniques and artificial intelligence. As such it is incumbent upon the modern clinician to be able to understand the basic assumptions required for multivariate analysis and also to realise when alternative statistical techniques should be employed.

Artificial Intelligence↗