Multispectral analysis of the temporal evolution of cerebral ischemia in the rat brain

A major difficulty in staging and predicting ischemic brain injury by magnetic resonance (MR) imaging is the time-varying nature of the MR parameters within the ischemic lesion. A new multispectral (MS) approach is described to characterize cerebral ischemia in a time-independent fashion. MS analysis of five MR parameters (mean diffusivity, diffusion anisotropy, T2, proton density, and perfusion) was employed to characterize the progression of ischemic lesion in the rat brain following 60 minutes of transient focal ischemia. k-Means (KM) and fuzzy c-means (FCM) classification methods were employed to define the acute and subacute ischemic lesion. KM produced an estimate of lesion volume that was highly correlated with postmortem infarct volume, independent of the age of the lesion. Overall classification rates for KM exceeded FCM at acute and subacute time points as follows: KM, 90.5%, 94.4%, and 95. 9%; FCM, 82.4%, 90.6%, and 82.6% (for 45 minutes, 180 minutes, and 24-120 hours post MCAO groups). MS analysis also offers a formal method of combining diffusion and perfusion parameters to provide an estimate of the ischemic penumbra (KM classification rate = 70.3%). J. Magn. Reson. Imaging 2000;12:842-858.

Effects of hormonal contraceptives on the periodontium, in a population of rural Sri-Lankan women

AIMS

Women using hormonal contraceptives can be considered to be a 'risk group' for periodontal disease, due to prolonged, sustained serum levels of oestrogens and progesterone. This investigation aims to study the effects of hormonal contraceptives on periodontal tissues.

METHODS

32 women using hormonal contraceptives for less than 2 years, 17 for 2-4 years and a matched control group of 39 non-users were selected for the study. They were clinically examined for plaque levels (plaque index: PLI), gingival condition (gingival index: GI) and loss of periodontal attachment (LA).

RESULTS

Contraceptive users of less than 2 years and 2-4 years duration (n=32, n= 17 respectively) and non-users (n=39) had similar oral hygiene levels; yet the contraceptive users had a significantly higher level of gingival inflammation, compared to the non-users (p<0.001; 1-way ANOVA). Usage of hormonal contraceptives for 2-4 years (n= 17) caused a significantly higher LA (p<0.001) compared to that of controls (n=39).

CONCLUSIONS

Usage of contraceptive preparations containing oestrogen and progesterone resulted in hormonal changes similar to those seen in pregnancy, associated with increased prevalence of gingivitis. There was significantly higher LA with prolonged usage of hormonal contraceptives, compared with controls.

Periodontal disease status during pregnancy and 3 months post-partum, in a rural population of Sri-Lankan women

OBJECTIVES

The aim of this investigation was to study the effects of pregnancy on the periodontium, in a rural population of Sri-Lankan women.

METHODS

The study group consisted of 47 pregnant women and 47 non-pregnant women who served as matched controls. All subjects were examined for plaque (plaque index: PLI), gingival condition (gingival index: GI) and loss of periodontal attachment (LA) levels, 4 x during the study, at 3-monthly intervals.

RESULTS

Despite similar scores for plaque levels in both pregnant and non-pregnant women, the GI of pregnant women was significantly increased, during the 1st and 2nd trimesters compared to the controls (p<0.01, 2-way ANOVA). During the 3rd trimester, GI was further increased (p<0.001), but dropped at 3 months post-partum. Values for LA did not show significant differences from that of controls, during any of the stages of pregnancy.

CONCLUSIONS

The results of this study show that pregnancy had an effect only on the gingivae and not on periodontal attachment levels. The effects of oestrogen and progesterone could give rise to a more florid response to the irritant effects of plaque, resulting in severe gingivitis.

Secondary decline in apparent diffusion coefficient and neurological outcomes after a short period of focal brain ischemia in rats

This study was designed to characterize the initial and secondary changes of the apparent diffusion coefficient (ADC) of water with high temporal resolution measurements of ADC values and to correlate ADC changes with functional outcomes. Fourteen rats underwent 30 minutes of temporary middle cerebral artery occlusion (MCAO). Diffusion-, perfusion-, and T2-weighted imaging was performed during MCAO and every 30 minutes for a total of 12 hours after reperfusion (n = 6). Neurological outcomes were evaluated during MCAO, every 30 minutes for a total of 6 hours and at 24 hours after reperfusion (n = 8). The decreased cerebral blood flow during MCAO returned to normal after reperfusion and remained unchanged thereafter. The decreased ADC values during occlusion completely recovered at 1 hour after reperfusion. The renormalized ADC values started to decrease secondarily at 2.5 hours, accompanied by a delayed increase in T2 values. The ADC-defined secondary lesion grew over time and was 52% of the ADC-defined initial lesion at 12 hours. Histological evaluation demonstrated neuronal damage in the regions of secondary ADC decline. Complete resolution of neurological deficits was seen in 1 rat at 1 hour and in 6 rats between 2.5 and 6 hours after reperfusion; no secondary neurological deficits were observed at 24 hours. These data suggest that (1) a secondary ADC reduction occurs as early as 2.5 hours after reperfusion, evolves in a slow fashion, and is associated with neuronal injury; and (2) renormalization and secondary decline in ADC are not associated with neurological recovery and worsening, respectively.

Multimodal evoked potentials and the ovarian cycle in young ovulating women

There is controversy over how hormonal conditions influence cerebral physiology. We studied pattern-shift visual evoked potentials (PS-VEP), brain stem auditory evoked potentials (BAEP) and short-latency somatosensory evoked potentials (SSEV) in 20 female volunteers at different phases of the menstrual cycle (estrogen phase, ovulatory day and progesterone phase). Statistical analysis showed decreased latencies for P100 (PS-VEP), N19 and P22 (SSEV) waves in the progesterone phase compared with the estrogen phase. There was no significant difference between the estrogen and the ovulation day values. Comparing the three above stages, there were no significant differences in the brainstem auditory evoked potentials. The reduction of the latencies of the potentials generated in multisynaptic circuits provides the first consistent neurophysiological basis for a tentative comprehension of human pre-menstrual syndrome.

Transient and permanent resolution of ischemic lesions on diffusion-weighted imaging after brief periods of focal ischemia in rats : correlation with histopathology

BACKGROUND AND PURPOSE

The early ischemic lesions demonstrated by diffusion-weighted imaging (DWI) are potentially reversible. The purposes of this study were to determine whether resolution of initial DWI lesions is transient or permanent after different brief periods of focal brain ischemia and to evaluate histological outcomes.

METHODS

Sixteen rats were subjected to 10 minutes (n=7) or 30 minutes (n=7) of temporary middle cerebral artery occlusion or sham operation (n=2). DWI, perfusion-weighted imaging (PWI), and T(2)-weighted imaging (T(2)WI) were performed during occlusion; immediately after reperfusion; and at 0.5, 1.0, 1.5, 12, 24, 48, and 72 hours after reperfusion. After the last MRI study, the brains were fixed, sectioned, stained with hematoxylin and eosin, and evaluated for neuronal necrosis.

RESULTS

No MRI or histological abnormalities were observed in the sham-operated rats. In both the 10-minute and 30-minute groups, the perfusion deficits and DWI hyperintensities that occurred during occlusion disappeared shortly after reperfusion. The DWI, PWI, and T(2)WI results remained normal thereafter in the 10-minute group, whereas secondary DWI hyperintensity and T(2)WI abnormalities developed at the 12-hour observation point in the 30-minute group. Histological examinations demonstrated neuronal necrosis in both groups, but the number of necrotic neurons was significantly higher in the 30-minute group (95+/-4%) than in the 10-minute group (17+/-10%, P<0.0001).

CONCLUSIONS

Transient or permanent resolution of initial DWI lesions depends on the duration of ischemia. Transient resolution of DWI lesions is associated with widespread neuronal necrosis; moreover, permanent resolution of DWI lesions does not necessarily indicate complete salvage of brain tissue from ischemic injury.

Temporal evolution of ischemic injury evaluated with diffusion-, perfusion-, and T2-weighted MRI

OBJECTIVE

Ischemic lesions seen on diffusion-weighted imaging (DWI) are reversible if reperfusion is performed within minutes after the onset of ischemia. This study was designed to determine whether acute reversibility of DWI abnormalities is transient following brief temporary focal brain ischemia and to characterize the temporal evolution of in vivo ischemic lesions.

METHODS

Eight rats were subjected to 30 minutes of temporary middle cerebral artery occlusion and underwent diffusion-, perfusion-, and T2-weighted MRI during occlusion; immediately after reperfusion; 30, 60, and 90 minutes after reperfusion; and 12, 24, 48, and 72 hours after reperfusion. Average apparent diffusion coefficient (ADCav) values and the cerebral blood flow index (CBFi) ratio were calculated in both the lateral caudoputamen and overlying cortex at each time point. The size of the in vivo ischemic abnormalities was calculated from the ADCav and the T2 maps. Postmortem triphenyltetrazolium chloride (TTC) staining was used to verify ischemic injury.

RESULTS

Both the CBFi ratio and ADCav values declined significantly in the two regions during occlusion. The CBFi ratio recovered immediately after reperfusion and remained unchanged over 72 hours. However, ADCav values returned to normal at 60 to 90 minutes and secondarily decreased at 12 hours after reperfusion as compared with those in the contralateral hemisphere. The extent of the in vivo ischemic lesions maximized at 48 hours and was highly correlated with TTC-derived lesion size.

CONCLUSIONS

Acute recovery of initial ADCav-defined lesions after reperfusion is transient, and secondary ADCav-defined lesions develop in a slow and delayed fashion.

Prevalence of Helicobacter pylori infection in patients with functional dyspepsia

OBJECTIVE

To investigate the prevalence of Helicobacter pylori infection in patients with functional dyspepsia.

DESIGN

Prospective descriptive study.

SETTING

Surgical unit, Base Hospital, Panadura.

PATIENTS

67 patients with persistent symptoms suggestive of functional dyspepsia but no clinical, endoscopic or ultrasonographic evidence of peptic, biliary, pancreatic or malignant disease.

METHODS

Upper gastrointestinal endoscopy and two antral mucosal biopsies were performed in all patients and the rapid urease test (CLO test) was done to detect H pylori status. All patients gave informed consent.

RESULTS

Of the 67 patients (32 males) with a mean age of 45 years (35 to 70 years), only 2 patients (2.9%) were found to be positive for H pylori infection.

CONCLUSION

Incidence of H pylori infection was found to be very low in patients with functional dyspepsia.

Neuroprotective effects of a novel broad-spectrum cation channel blocker, LOE 908 MS, on experimental focal ischemia: a multispectral study

Thirty-four rats undergoing 90 minutes of temporary middle cerebral artery occlusion were randomly and blindly assigned to vehicle or (RS)-(3,4-dihydro-6, 7-dimethoxyisoquinoline-1-gamma1)-2-phenyl-N,N-di-2-(2, 3, 4-trimethoxyphenyl)ethyl acetamide (LOE 908 MS; 0.5 mg/kg) i.v. bolus at 30 minutes after arterial occlusion followed by a 5 mg/kg/hr i.v. infusion for 3.8 hours (n =17/group). Perfusion-, diffusion- and T(2)-weighted magnetic resonance imaging was performed before treatment and repeatedly after treatment. Multispectral analysis was used to define ischemic abnormalities. The size of the ischemic abnormalities, including the ischemic core and penumbra, was not different between the two groups before treatment. However, a significant difference in ischemic lesion size was detected beginning 1.5 hours after treatment. The size of the ischemic core was significantly smaller in the treatment group, while the size of the ischemic penumbra was similar in the two groups at 85 minutes after arterial occlusion. Postmortem infarct size at 24 hours was significantly smaller in the drug-treated group than in the placebo group. These results demonstrate that LOE 908 MS can reduce ischemic lesion size, which is probably attributable to inhibition of expansion of the ischemic core. J. Magn. Reson. Imaging 1999;10:138-145.

Lymphoid hyperplasia, CD45RBhigh to CD45RBlow T-cell imbalance, and suppression of Type I diabetes mellitus result from TNF blockade in NOD-->NOD-scid adoptive T cell transfer

Sustained antibody-mediated inhibition of tumor necrosis factor (TNF) activity offers protection against Type I (insulin-dependent) diabetes mellitus in non-obese diabetic (NOD) mice. The mechanism of this effect, however, has remained obscure: TNFalpha might be required for the development of specific immune responses to islet antigens or it could directly participate in destruction of beta cells. In this study, autoimmune destruction of beta cells was initiated in NOD-severe combined immunodeficient (scid) mice by transfer of NOD splenic T-cells to induce diabetes. The blockade of TNFalpha activity was achieved during a narrow window of time after transfer. Transient inhibition of TNFalpha greatly reduced the number of islet lymphocytes and the incidence of diabetes in recipients of prediabetic NOD spleen cells. Protection extended beyond the interval of effective TNF blockade. Furthermore, the protective effect was only observed if cells were obtained from 6-week-old donors. The suppression of autoimmunity was reversible in the context of adoptive transfer as indicated by the transfer of splenocytes from the primary recipient to a second NOD-scid host led to a diabetic outcome. The blockade of TNFalpha was accompanied by a considerable increase in spleen size and doubling of the total splenocyte count, suggesting that TNFalpha might normally eliminate a transplanted T-cell subset within the recipients. Further analysis showed an increase in the absolute count of CD4 + T cells and pronounced distortion of the CD45RBhigh to CD45RBlow ratio, with a relative augmentation in the CD45RBlow count in the spleen. TNFalpha appears to regulate the number and subtype distribution of a transplanted T cell population.

Teleradiology at a children's hospital: a pilot study

A pilot teleradiology project was conducted between the Royal Alexandra Hospital for Children in Camperdown, central Sydney, and Nepean Hospital in Penrith, about 48 km away. Over three months 575 paediatric radiographs were transmitted at full resolution. The results demonstrated that it was possible to transmit paediatric chest images of diagnostic quality in a reliable and secure manner. Mean transmission time per image was 3.26 min using ISDN, which was considered to be acceptable. Costs were calculated in terms of transmission, equipment, maintenance and staff components. The cost per image transmitted would vary from A$80 for 2500 images per year to A$34 for 10,000 images per year. The experience of the pilot study suggested that more widespread introduction of high-quality paediatric telemedicine in Australia would be feasible. Adoption of the technique would have major implications for paediatric health care, including potential improvements in patient management due to quicker diagnosis and earlier intervention, and potential savings through avoiding transfer of some emergency cases.

Reconsiderations about the clinical importance of the sympathetic skin response

Over the last few years, neurologists have been showing increasing interest in the study of the sympathetic skin response (SSR). In the present report we describe a simple method that permitted us to determine a wide variation of SSR in response to different stimuli such as respiration, deglutition, blinking, skeletal movements, biting, auditory or light stimuli, vocalization, and sphincter contraction. These results raise doubts about the role of SSR as a complementary diagnostic method.

Severe cervical dysplasia and nasal cartilage calcification following prenatal warfarin exposure

We present an infant who was exposed to warfarin throughout pregnancy and has warfarin embryopathy. When the child was examined radiologically at 20 months areas of calcification were visible in the septal and alar cartilages of the small external part of the nose. The location of this ectopic calcification is consistent with that seen in an animal model of the warfarin embryopathy. It supports the hypothesis that warfarin interferes with the prenatal growth of the cartilaginous nasal septum by inhibiting the normal formation of a vitamin K-dependent protein that prevents calcification of cartilage. The child also had severe abnormalities of the cervical vertebrae and secondary damage to the spinal cord. Cervical vertebral anomalies are a relatively common finding in the warfarin embryopathy and in the related Binder syndrome.

Compression of the peripheral branches of the sciatic nerve by lipoma

The authors report two female patients with chronic sensitive and motor findings in lower limbs caused by compression of distal branches of sciatic nerve by lipoma. Similar cases were not described on literature. Nerve conduction studies allowed to localize the exact site of compression. At surgery, lipomas compressing the deep peroneal nerve (case 1) and the posterior tibial nerve (case 2) were observed. Histologic studies of tumors confirmed the diagnoses.

Prenatal testing to predict the severity of hemolytic disease of the fetus and newborn

The severity of hemolytic disease of the fetus or newborn can be assessed with certainty only by measurement of fetal parameters. However, these invasive procedures are not without risk for the fetus. Most erythrocyte antibodies do not cause significant hemolytic disease of the fetus or newborn and various assays are available to assist obstetricians in predicting the likely effect of maternal alloantibodies on fetal erythrocytes. Initially, immunohematologic tests are performed on maternal serum to identify antibodies with a potential for causing hemolytic disease of the fetus or newborn. Antibody concentration is measured by indirect antiglobulin technique titration, or where possible (for anti-D or -c), by quantitation. When used consecutively throughout pregnancy, these tests will reveal a trend that helps to predict the likelihood of hemolytic disease of the fetus or newborn. Functional assays (antibody-dependent cell-mediated cytotoxicity and chemiluminescence) are probably superior to serologic tests for predicting hemolytic disease of the fetus or newborn. Unfortunately, the assays do not reflect accurately the in vivo conditions for a given patient. Knowledge of the immunoglobulin subclass can help to assess the hemolytic potential of maternal antibody, but quantitative measurement of subclasses is still experimental. Diagnostic testing should be approached in a structured manner, commencing with simple serology, followed, in selected cases, by more complex functional assays and indirect fetal tests to identify those fetuses at greatest risk. This approach will enable direct fetal tests to be undertaken only when there is strong suspicion of severe hemolytic disease of the fetus or newborn.

Effect of long-term treatment with insulin and/or acarbose on glomerular basement membrane thickening in alloxan-diabetic rats

Acarbose is a competitive inhibitor of the intestinal alpha-glycosidases, that can delay absorption of intestinal carbohydrates causing their malabsorption. In the present paper we studied the effects of insulin, acarbose and their association on glomerular basement membrane thickening in alloxan-diabetic rats. Twenty-five male and female Wistar rats, approximately 3 months old at the beginning of the experiment, were assigned randomly to each of five experimental groups: normal control rats, alloxan-diabetic control rats, alloxan-diabetic rats treated with acarbose, alloxan-diabetic rats treated with insulin, and alloxan-diabetic rats treated with insulin plus acarbose. Alloxan was administered in a single i.v. dose of 442 mg/kg body weight. Insulin was given subcutaneously at doses of 18 to 30 IU/kg corrected daily on the basis of glycosuria and ketonuria. Acarbose was given mixed with rat chow in a dose of 50 mg/100 g chow. Body weight, water and food intake and diuresis, as well as blood and urine glucose were determined after 1, 3, 6, 9, and 12 months of treatment. Glomerular basement membrane (GBM) thickening was determined by electron microscopy at the same times. Clear clinical and laboratory signs of severe diabetes, with blood glucose levels above 200 mg/dl and urine glucose above 3000 mg/dl, were observed in all alloxan-diabetic control rats, in all periods of follow-up, whereas administration of insulin or acarbose reduced the blood glucose levels of treated groups. The most satisfactory control of blood and urine glucose was observed in animals treated with both insulin and acarbose. However, diarrhea was observed in diabetic rats treated with acarbose associated or not with insulin. GBM thickening was correlated with age in all groups. Beginning at six months after diabetes induction, the GBM of untreated diabetic rats was significantly thicker (mean +/- SEM, 4.446 +/- 0.45 mm) than that of normal rats (2.977 +/- 0.63mm). Both insulin and acarbose prevented GBM thickening and their combination induced thickening similar to the age dependent thickening observed for normal rats of the same age. We conclude that acarbose when combined with insulin may be a good option in the control of diabetes and its renal complications.

Midline interhemispheric fusion associated with atypical callosal dysgenesis: a mild type of holoprosencephaly

We report the imaging findings in a 3 year old girl with a mild form of holoprosencephaly. The malformation is of interest because it may contribute to our understanding of brain development. The relatively mild clinical features are emphasized.

New technologies for red-cell serology

Until 1943, blood-grouping tests were performed mainly on glass slides or tiles but, following the description of the antiglobulin test, tube techniques became widespread. With increasing workloads and pressure to be ever more cost-efficient, other 'reaction vessels' such as microplates have been developed for blood-group serological testing. The indirect antiglobulin test has been shown to be the most effective and reliable method for detecting clinically significant antibodies. As a result, this test has been developed, for example by the introduction of enhancement media such as low-ionic-strength saline and polyethylene glycol. However, the problems and inconvenience associated with the labelling and washing of large numbers of tubes were not overcome until the introduction of the solid-phase antiglobulin test and the newer microtubes containing gel or glass microbeads. These techniques are now replacing the conventional tube tests, but they too have their own limitations. There is still no single technique that will detect all clinically significant red-cell antibodies. Therefore, the safe transfusion of red cells that would survive optimally in the recipient depends not on a single test but on a series of tests and procedures, such as correct patient identification, blood-grouping, antibody-screening and compatibility-testing.

Randomised comparative monotherapy trial of phenobarbitone, phenytoin, carbamazepine, or sodium valproate for newly diagnosed childhood epilepsy

BACKGROUND

The medical treatment of childhood epilepsy is largely influenced by clinical trials in adult patients. We know of only one randomised comparative trial (of two drugs) in newly diagnosed childhood epilepsy. We have undertaken a long-term, prospective, randomised, unmasked, pragmatic trial of the comparative efficacy and toxicity of four standard antiepileptic drugs used as monotherapy in children with newly diagnosed epilepsy.

METHODS

Between 1981 and 1987, 167 children aged 3-16 years, who had had at least two previously untreated tonic-clonic or partial seizures, with or without secondary generalisation, were randomly allocated treatment with phenobarbitone, phenytoin, carbamazepine, or sodium valproate. The protocol was designed to conform to standard clinical practice. Efficacy was assessed by time to first seizure after the start of treatment and time to achieving 1-year remission.

FINDINGS

The overall outcome with all four drugs was good. 20% of children remained free of seizures and 73% had achieved 1-year remission by 3 years of follow-up. We found no significant differences between the drugs for either measure of efficacy at 1, 2, or 3 years of follow-up. The overall frequency of unacceptable side-effects necessitating withdrawal of the randomised drug was 9%. This total included six of the first ten children assigned phenobarbitone; no further children were allocated this drug. Of the other three drugs, phenytoin (9%) was more likely to be withdrawn than carbamazepine (4%) or sodium valproate (4%). INTERPRETATION Our data will inform choice of drug and outcome with four of the standard drugs available for newly diagnosed tonic-clonic or partial seizures with or without secondary generalisation in children.