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T Knutson

Publications and source records attributed to T Knutson.

10 recordsLinked to original sources
PubMed2002

The effect of amiloride on the in vivo effective permeability of amoxicillin in human jejunum: experience from a regional perfusion technique.

The purpose of this human intestinal perfusion study (in vivo) was twofold. Firstly, we aimed to determine the effective in vivo jejunal permeability (P(eff)) of amoxicillin and to classify it according to the Biopharmaceutics Classification System (BCS). Secondly, we investigated the acute effect of amiloride on the jejunal P(eff) of amoxicillin. Amoxicillin, a beta-lactam antibiotic, has been reported to be absorbed across the intestinal mucosa by both passive diffusion and active transport. A regional single-pass perfusion of the jejunum was performed using a Loc-I-Gut perfusion tube in 14 healthy volunteers. Each perfusion lasted for 200 min and was divided into two periods of 100 min each. The concentration of amoxicillin entering the jejunal segment was 300 mg/l in both periods, and amiloride, an inhibitor of the Na+/H+ exchanger, was added at 25 mg/l in period 2. The concentrations of amoxicillin and amiloride in the outlet jejunal perfusate were measured with two different HPLC-methods. Antipyrine and [14C]PEG 4000 were added as internal standards to the perfusion solution. Amiloride had no significant effect on the jejunal P(eff) of amoxicillin. The human in vivo jejunal P(eff) for amoxicillin was 0.34+/-0.11 x 10(-4) and 0.46+/-0.12 x 10(-4) cm/s in periods 1 and 2, respectively. The high jejunal P(eff) for amiloride was 1.63+/-0.51 x 10(-4) cm/s which predicts an intestinal absorption of more than 90%. Following the BCS amoxicillin was classified as a low P(eff) drug, and amiloride had no acute effect on the in vivo jejunal P(eff) of amoxicillin.

Adult↗
PubMed2001

Axon collaterals of Meynert cells diverge over large portions of area V1 in the macaque monkey.

Patchy intrinsic connections, originating mainly from horizontal collaterals of pyramidal neurons, have been demonstrated in area V1 and many other cortical areas. In this article, we identify a network of intrinsic connections concentrated in layer 6 of area V1. These are visualized by extracellular injections of anterograde tracers in V1, which label small clusters of large terminal boutons in layer 6, in conjunction with thick axon segments. These segments can be traced back to infragranular Meynert cells (n = 10), which are retrogradely labeled from the injections. By using serial section analysis, we identified the following features of this distinctive system of Meynert cell collaterals: (1) terminal clusters are relatively small (<100 microm); (2) each cluster has a small number of rather large boutons (up to 3.0 microm); (3) there is typically a termination-free zone in the immediate vicinity (0.5-2.0 mm) of the cell body; (4) a single neuron has multiple branches that can extend up to 8.0 mm from the soma; and (5) the collaterals are concentrated in layer 6. These features are different from those of horizontal intrinsic connections in the supragranular layers of area V1. They are consistent with fast dynamics and a possible role in wide-field motion processing, such as has been associated with Meynert cells from other studies.

Animals↗
PubMed2001

BPH with coexisting overactive bladder dysfunction--an everyday urological dilemma.

The aim of this study was to use a systematic schedule, including urodynamics, to describe the rate of coexisting overactive bladder (OB) in patients with bladder outlet obstruction (BOO) caused by benign prostatic hyperplasia (BPH). We also identified differences between the patients with pure BOO compared with those with BOO combined with OB (BOO + OB). One hundred and sixty-two men referred to our clinic due to LUTS were included. Patients with a history that might affect their bladder function were excluded. After cystometry and pressure-flow studies, the patients were divided into pure BOO and BOO + OB. Of the 162 men, 55% had pure BOO. BOO + OB was found in 45%. Age, s-PSA, voided volume, and obstruction grade differed significantly between the groups. The patients with BOO + OB were older, had a higher s-PSA, voided smaller volumes, and were more obstructed. We found no differences in TRUS-volume, Q-max, IPS score, or PVR. There was a strong association between OB and BOO, the percentage of OB increasing with increased obstruction. TRUS-volume, Q-max, IPS score, and PVR did not predict whether the patients had a combined BOO + OB or not. These findings indicate that BOO is a progressive disease, which in time causes pronounced obstruction and perhaps in itself contributes to the development of OB.

Aged↗
PubMed2001

Invasive urodynamic studies are well tolerated by the patients and associated with a low risk of urinary tract infection.

OBJECTIVE: An essential part of investigation of the lower urinary tract is pressure/flow studies (pQS). In fact, pQS is the only way of diagnosing bladder outlet obstruction. There is controversy regarding whether or not prophylactic antibiotic treatment is necessary. This prospective study was carried out in order to determine the frequency of infections and/or distress after pQS performed without the use of antibiotic prophylaxis. MATERIAL AND METHODS: One hundred and twenty-three patients were included in the present study, all males. They were requested to answer a questionnaire I week after pQS. Questions were asked concerning symptoms of voiding disorders, dysuria, hematuria, incidence of fever and the patient's acceptance of the investigation after the pQS procedure. Urine was obtained for culture immediately before the investigation and 3 and 7 days after the pQS. RESULTS: Forty-six per cent of the patients experienced some degree of transient dysuria after pQS. and 18.5% experienced voiding problems of varying nature. Five per cent of the patients had hematuria and 2.5% reported fever. Fifty per cent of the patients experienced some degree of discomfort during the pQS investigation, and 4.1% had positive culture and symptoms of UTI requiring antibiotic treatment. CONCLUSIONS: PQS is well accepted by the patients and the regular use of propylactic antibiotics is not indicated. We recommend, though, that patients at risk for serious complications from infections (e.g. those with prosthetic heart valves) should receive prophylactic antibiotics.

Algorithms↗
PubMed2001

Can urodynamic assessment of outflow obstruction predict outcome from watchful waiting?--A four-year follow-up study.

OBJECTIVE: One of the most common "treatment" alternatives in suspected outflow obstruction due to bladder outlet obstruction (BOO) is watchful waiting (WW). The aim of this study was to see whether there were any differences in outcome between patients with slight, moderate or severe obstruction due to BOO as classified by transrectal ultrasound (TRUS) and urodynamics. MATERIAL AND METHODS: Thirty-seven men with lower urinary tract symptoms (LUTS) and suspected BOO were included. All of the patients were investigated by a routine investigation schedule, including TRUS and urodynamics with pressure-flow measurement (pQS) at baseline. Patients with cancer in the urinary tract, prostatitis, history of detrusor hyperreflexia (peripheral or central diseases or trauma to the nervous system affecting the bladder) and serious systemic diseases were excluded. Patients were examined at baseline, then checked again after 1 year and 4 years. Patients who did not want to continue with WW were listed as treatment failures. RESULTS: At baseline, 43.2% of the patients were urodynamically severely obstructed and 32.3% were moderately obstructed. Thirty-five per cent of the patients were found to have previously unknown detrusor hyperactivity/overactivity. The prevalence of detrusor hyperactivity/overactivity increased with BOO. After 1 year, IPSS had decreased at unchanged Qmax and postresidual volume. These findings persisted at 4 years. The failure rate increased in the more obstructed patients and was significantly higher with more severe obstruction. Complications were found in 13.5%, with no significant differences between patients with minor BOO [Detrusor Adjusted Mean PURR Factor (DAMPF) scale <42], moderate BOO (DAMPF 42-65) and severe BOO (DAMPF >65). CONCLUSIONS: In patients with severe BOO, the LUTS and failure rate increase over time. The percentage of patients with detrusor hyperactivity/overactivity was higher in the severely obstructed group. By including full urodynamics when investigating patients with BOO, it seems possible to predict the failure rate according to the patients' obstruction grade. This gives an opportunity to treat the patient with minimal invasion, and to give the individual patient a more precise prognosis if WW is preferred.

Adult↗
PubMed2001

Pressure-flow studies for patient selection in the treatment of symptomatic BPH--a one-year follow-up study.

OBJECTIVE: Many different treatments for lower urinary tract symptoms (LUTS) due to bladder outlet obstruction (BOO) are available today. To select the most suitable method for each patient is therefore a delicate task. The aim of this study has been to use a standardised systematic investigation schedule including pressure flow studies (pQS) in order to try to use graded treatment according to obstruction. METHODS: Ninety-nine patients were systematically examined with routine investigations and pQS to select between 3 treatment options, TURP, TUMT 2.0 (low energy) and watchful waiting (WW). Patients with severe BOO were recommended TURP, patients with moderate BOO were treated with TUMT and patients with no or minor BOO were recommended WW. RESULTS: TURP produced the best improvement in maximum free flow (Q-max), IPS-score and PVR, but only TURP had serious complications. TUMT treatment produced a more moderate improvement in flow rate, IPS-score and PVR, and all of the complications were minor. WW did not improve PVR or Q-max but the IPS-score decreased significantly. One UTI was the only complication in the WW group. CONCLUSIONS: pQS can be used to allocate patients with LUTS due to suspected BOO into different treatment arms; TURP, TUMT, WW, all with known different effects of BOO and with different severity of complications. Good symptomatic effect in Q-max, PVR and IPS-score with less serious complications and at low failure rate can thereby be obtained.

Aged↗
PubMed2000

Feedback connections from area MT of the squirrel monkey to areas V1 and V2.

Area MT/V5 is reciprocally connected with both V1 and V2; but, despite extensive anatomical and physiological investigations, detailed information on the feedback component of these connections is still not available. The present report uses serial section reconstruction of single axons, labeled by anterograde tracers injected in area MT of squirrel monkeys, to characterize these connections further. As with other feedback systems, MT axons terminating in both areas V1 (n = 9) and V2 (n = 6) are widely divergent. In area V1, MT fields are larger than those from V2 and are about comparable to those from V4 or TEO. Terminations in V1, unlike other feedback connections described so far, terminate in several laminar combinations: only layer 1 (n = 2); only layer 4B (n = 3); layers 1 and 4B (n = 1); and layers 1, 4B, and 6 (n = 3). In V2, they occur mainly in layers 1 and 5 or 6. Terminations have two patterns even within a single axon: strung along collateral segments and grouped within small clusters. There are no apparent differences in the size, shape, or density of terminal specializations in V1 or V2, and, consistently with previous double-labeling experiments (Kennedy and Bullier [1985] J Neurosci 5:2815-2830), some axons can branch to both areas. This result, along with the laminar evidence for subtypes of feedback connections, argues against an exclusively hierarchical organization based on "pairwise" connectivity. For V1 and MT, there may be directly reciprocal loops between feedforward and feedback projecting neurons, but this is less likely to be so for V2 and MT.

Animals↗
PubMed1999

Home uroflowmetry: improved accuracy in outflow assessment.

To study home uroflowmetry and to compare this method to free or "traditional" uroflowmetry in the evaluation of the patient with symptomatic benign prostatic hyperplasia (BPH), and the relationship between the values of home uroflowmetry parameters and bladder outlet obstruction (BOO). Twenty-five patients (mean age, 67 years) with symptomatic BPH were examined with home uroflowmetry, free uroflowmetry, and pressure-flow measurement. The patients were assessed using the International Prostate Symptom score; digital rectal examination; routine blood chemistry, including serum prostate-specific antigen level; urinanalysis; transrectal ultrasonography; and post-void residual urine. The 24 hr were divided into "active time" (AT) and "sleep time" (ST). AT home uroflowmetry parameters were compared to ST ones. The home uroflowmetry parameters were compared to respective ones of the free uroflowmetry as well and those obtained by pressure-flow measurement. The patients were asked about their opinion of home uroflowmetry. Home uroflowmetry was found to be a simpler and more acceptable method than free uroflowmetry. The mean Qmax of AT was significantly greater than the mean Qmax of ST, but the mean voided volume and mean voiding time of ST were significantly larger than those of AT. There was a close relationship between the mean Qmax at home and the Qmax in hospital, but the voided volume and voiding time measured in hospital were significantly larger than those at home. Home uroflowmetry provided an estimation of BOO for 46% of the patients as low if the home mean Qmax was >14 ml/sec, and as high if the home mean Qmax was <10 ml/sec. Home uroflowmetry was well accepted by the patients and gave more information than free uroflowmetry. In 46% of the cases, an estimation of BOO was obtained with home uroflowmetry.

Aged↗