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Biomedical subjects

L Jonsson

Publications and source records attributed to L Jonsson.

At least 19 recordsLinked to original sources
PubMed1998

beta-cell-specific inactivation of the mouse Ipf1/Pdx1 gene results in loss of the beta-cell phenotype and maturity onset diabetes.

To study the late beta-cell-specific function of the homeodomain protein IPF1/PDX1 we have generated mice in which the Ipf1/Pdx1 gene has been disrupted specifically in beta cells. These mice develop diabetes with age, and we show that IPF1/PDX1 is required for maintaining the beta cell identity by positively regulating insulin and islet amyloid polypeptide expression and by repressing glucagon expression. We also provide evidence that IPF1/PDX1 regulates the expression of Glut2 in a dosage-dependent manner suggesting that lowered IPF1/PDX1 activity may contribute to the development of type II diabetes by causing impaired expression of both Glut2 and insulin.

Amyloid↗
PubMed1997

Serial gadolinium-enhanced magnetic resonance imaging and assessment of facial nerve function in Bell's palsy.

Eleven patients with mild or moderate acute idiopathic peripheral facial palsy, so-called Bell's palsy, were serially examined by gadolinium-DTPA-enhanced MRI on mean days 11, 40, and 97 (third examination, n = 10) after the onset of palsy. Results of the clinical and neurophysiologic assessment of facial nerve function were compared with the gadolinium-enhanced MRI findings. Eight of the 11 patients demonstrated contrast enhancement of the facial nerve at the initial examination, but in 7 of them, the enhancement had disappeared by the time of the serial follow-up gadolinium-enhanced MRI scans. The disappearance of facial nerve enhancement was found to be related to clinical and neurophysiologic improvements in facial nerve function during recovery from Bell's palsy. The three patients whose scans were negative at the initial gadolinium-enhanced MRI examination had the same clinical severity of palsy, but initially they had milder neurophysiologic involvement than those who demonstrated enhancement; these three patients did not exhibit enhancement at serial follow-up scans. These findings indicate that the presence of enhancement at the initial MRI scan is not necessarily indicative of a poor prognosis for recovery.

Acute Disease↗
PubMed1996

Dental conditions and temporomandibular joints in an early mesolithic bog man.

In 1994 parts of a human skeleton were found in the county of Västergötland, Sweden. The remains were probably from a man and estimated according to 14C dating to be about 9800 years old, i.e. from the Early Mesolithic Period. As such old finds are rare and the skull was well preserved a more detailed description is presented in this paper. The facial skeleton was robust and the face shape was rectangular. The remaining teeth, one maxillary and 10 mandibular teeth, exhibited no caries but extensive occlusal wear which in some teeth had exposed the pulp and led to periapical osteitis. Besides these teeth the 4 maxillary incisors and the two canines and one incisor in the mandible had been lost post-mortem, probably because of severe marginal bone loss. Both temporomandibular joints showed remodelling, one also osteoarthrotic changes. The observations are discussed with respect to masticatory function and some background factors.

Alveolar Bone Loss↗
PubMed1995

Gd-DPTA enhanced MRI in Bell's palsy and herpes zoster oticus: an overview and implications for future studies.

Magnetic resonance imaging (MRI) is a new and important tool for use in diagnosing and investigating diseases affecting the facial nerve. In recent gadolinium-DTPA enhanced MRI (Gd-MRI) studies it has unequivocally been demonstrated that ipsilateral facial nerve contrast enhancement, predominantly in the meatal portion, is present in both Bell's palsy and herpes zoster oticus. In this overview, the results of MRI studies performed on patients with acute peripheral facial palsy, especially Bell's palsy and herpes zoster oticus, are discussed. The Gd-MRI pattern in Bell's palsy is very similar to that seen in herpes zoster oticus, and the findings reported so far support the theory that an inflammation may be the cause of the nerve injury in both cases. So far, however, Gd-MRI has not been helpful in evaluating the severity and/or prognosis of the facial palsy. Further studies employing improved techniques, including three-dimensional fast (or turbo) spin echo (3DFSE) MRI with heavily T2-weighted sections and high resolution three-dimensional Fourier transform (3DFT) MRI, need to be conducted in order to determine whether it is possible to follow the course of the disease and whether MRI and/or Gd-MRI are useful prognostic tools in the early stages of palsy.

Contrast Media↗
PubMed1994

A new hybrid anaesthetic circuit for a low-flow rebreathing technique.

The coaxial Mapleson D (Bain) circuit is close to an ideal anaesthetic breathing circuit but it requires a high fresh gas flow (VF). The CO2 absorber circuit can be used with a low VF but the patient end is clumsy and hyperventilation is common unless a small tidal volume (VT) and a low respiratory frequency (f) is used. To overcome these problems a new hybrid anaesthetic circuit has been constructed. The new system has a slender coaxial patient end, connected to a Y-piece and a CO2 absorber circuit with unidirectional valves. The VF supply runs inside the coaxial tube to the patient end, similar to the Bain circuit. The new circuit was tested with simulated controlled ventilation in a lung model and compared to an absorber circuit, an absorber circuit with an added 300 ml dead space (VD) and a Bain circuit. The fraction of end tidal CO2 (FECO2) was measured as a function of VF. With VF 11 min-1, VT 10 ml.kg-1 and f 12 breaths min-1 a simulated 70 kg patient had an FECO2 of 4.8% and a 40 kg patient 5.5% with VF 21.min-1. At zero VF the new system was equal to an absorber circuit with 300 ml VD. With increasing VF the FECO2 in the new circuit decrease towards the absorber circuit values. The new system combines the benefits of the Bain circuit with those of a low flow CO2 absorber circuit and offers flexibility in the choice of combinations of VT, f and VF.

Anesthesia, Closed-Circuit↗
PubMed1993

Biosynthesis of vernoleate (cis-12-epoxyoctadeca-cis-9-enoate) in microsomal preparations from developing endosperm of Euphorbia lagascae.

Epoxidated fatty acids are the major constituents of the triacylglycerols in a few plant species. We have investigated the biosynthesis of vernolic acid (cis-12-epoxyoctadeca-cis-9-enoic acid) in the seed oil of Euphorbia lagascae. Microsomes were isolated from developing endosperm. The membrane lipids were labeled in situ with [14C]oleate or [14C]linoleate, which mainly were recovered in phosphatidylcholine (PC), and the metabolization of the radioactive fatty acids was followed in incubations with or without NADPH. In the presence of NADPH, [14C]vernoleate was formed. After short incubations, most of the vernolic acid was found in PC, but with increasing incubation times, the free acid dominated. The synthesis of vernoleate was inhibited by carbon monoxide, but not by cyanide. The presence of anticytochrome b5 antibodies inhibited both the desaturation of [14C]oleate to [14C]linoleate and the epoxidation of [14C]linoleate to [14C]vernoleate. Free linoleic acid did not serve as substrate for epoxidation. The results indicate that, in the endosperm of E. lagascae, vernoleate is synthesized on PC from linoleate, and that the epoxidation is catalyzed by a cytochrome P450 and involves cytochrome b5.

Epoxy Compounds↗
PubMed1993

Facial nerve enhancement in Bell's palsy demonstrated by different gadolinium-enhanced magnetic resonance imaging techniques.

Twenty-one patients with an acute complete peripheral facial palsy, Bell's palsy, were examined by medium- and high-Tesla magnetic resonance imaging. Three contrast techniques were used: intravenous gadolinium; oral carbohydrate and intravenous gadolinium; and gadolinium, carbohydrate, and readministration of gadolinium. Three to 22 days after the onset of palsy, 12 of the 21 patients demonstrated ipsilateral facial nerve enhancement, most consistently in the meatal region, which is indicative of an inflammatory reaction. Two to 4.5 months after the onset, the enhancement had disappeared in 10 of the 12 patients. For the individual patient, contrast-enhanced magnetic resonance imaging gave little or no help in predicting the outcome of palsy. It is speculated that the intake of carbohydrate and readministration of gadolinium may improve the sensitivity of medium-high-Tesla magnetic resonance imaging in some cases.

Administration, Oral↗
PubMed1993

Nausea: the most important factor determining length of stay after ambulatory anaesthesia. A comparative study of isoflurane and/or propofol techniques.

Speed of recovery and length of stay in hospital were studied in 95 ambulatory patients undergoing laparoscopy or arthroscopy. The patients were divided into three groups regarding maintenance of anaesthesia. Group A (n = 32) received isoflurane 0.7% end-tidally, group B (n = 31) propofol infusion for 25 min and thereafter isoflurane, and group C (n = 32) received an infusion of propofol throughout the procedure. Recovery was assessed by a combination of the Maddox-Wing, the Choice Reaction Time test and p-deletion. The awakening period was somewhat shorter in group A, but psychomotor recovery was somewhat slower compared to groups B and C. The length of stay in hospital depended on whether the patient was nauseated or not. In group A, 44% suffered from nausea requiring medical intervention compared to 13% and 19% in groups B and C, respectively. The stay in hospital was 235 +/- 90 min (mean +/- standard deviation) in group A compared to 184 +/- 56 min and 197 +/- 55 min in groups B and C, respectively. The non-nauseated patients in group A had a stay in hospital of 188 +/- 55 min compared to 184 +/- 52 and 184 +/- 37 in the non-nauseated patients in groups B and C, respectively. In total, the nauseated patients (n = 24) stayed 267 +/- 95 min compared to 185 +/- 47 min for the non-nauseated patients (n = 71), P < 0.001. We found nausea to be the most important factor determining length of stay after ambulatory anaesthesia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Immunocompetent cells in human nasal polyps and normal mucosa.

The distribution of T- and B-lymphocytes, HLA-DR-expressing cells, and macrophages was determined using monoclonal antibodies in frozen biopsy sections of nasal polyps from 12 patients, and of nasal mucosa from five disease-free controls. The relative proportion and spatial distribution of different lymphoid cells was similar with regards to both nasal polyps and normal mucosa. Numerous scattered T lymphocytes (Leu4-positive) and HLA-DR-expressing macrophage/dendritic-like cells were shown and tended to accumulate in the subepithelial areas. Aggregates of T lymphocytes and HLA-DR-positive cells were also found close to deeper glands. In the submucosal clusters, the Leu3a-positive ("helper/inducer") cells were more common than the Leu2a-positive ("suppressor/cytotoxic") cells. Furthermore, a number of epithelial, non-lymphoid cells were found to express the HLA-DR antigen, which suggests an active role for the epithelium in the immunological response of the normal mucosa as well as that of the nasal polyp.

Adult↗
PubMed1993

Inflammatory paranasal sinus disease in Bell's palsy demonstrated by magnetic resonance imaging.

The paranasal sinuses of 20 consecutive young adult patients with a complete Bell's palsy were investigated by magnetic resonance imaging (MRI) to obtain more information on the etiology of the disease. A high signal intensity on T2-weighted MRI was demonstrated in the paranasal sinuses, mainly the maxillary sinuses, in 12 of 20 (60%) patients in the early stage of Bell's palsy. Eleven of the 12 patients with positive MRI were followed up after 2 to 8 months (median 3 months), and in six of these, the bright signal intensity had disappeared, in two patients there was a regress, and in three patients the signal changes were persistent. The MRI findings indicate that transient inflammatory paranasal sinus disease, which may be caused by a viral and/or bacterial infection, infrequently may be associated with Bell's palsy. However, the relationship to the pathophysiologic process in Bell's palsy is still uncertain.

Adult↗
PubMed1992

Evidence for cytochrome b5 as an electron donor in ricinoleic acid biosynthesis in microsomal preparations from developing castor bean (Ricinus communis L.).

The major b-type cytochrome in microsomal membrane preparations from developing endosperm of castor bean (Ricinus communis) was cytochrome b5. Cytochrome P-450 was also present. The microsomal membranes had delta 12-hydroxylase activity and catalysed the NAD(P)H-dependent hydroxylation of oleate to yield ricinoleic acid. CO had no effect on the hydroxylase activity. Rabbit polyclonal antibodies were raised against the hydrophilic cytochrome b5 fragment purified from cauliflower (Brassica oleracea) floret microsomes. The anti-(cytochrome b5) IgG inhibited delta 12-hydroxylase, delta 12-desaturase and cytochrome c reductase activity in the microsomes. The results indicate that electrons from NAD(P)H were transferred to the site of hydroxylation via cytochrome b5 and that cytochrome P-450 was not involved.

Carbon Monoxide↗
PubMed1991

Ricinoleic acid biosynthesis and triacylglycerol assembly in microsomal preparations from developing castor-bean (Ricinus communis) endosperm.

Microsomal membrane preparations from the developing endosperm of castor bean (Ricinus communis) catalysed the transfer of oleate from [14C]oleoyl-CoA to phosphatidylcholine (PtdCho). In the presence of NADH, radioactive ricinoleate (12-hydroxyoctadec-9-enoate) was synthesized from [14C]oleate, and this was largely recovered in PtdCho and as free fatty acid. The addition of unlabelled ricinoleoyl-CoA to these incubation mixtures did not increase the low [14C]ricinoleate concentration found in the acyl-CoA fraction nor decrease the [14C]ricinoleate concentration in PtdCho and free fatty acid, and thus no evidence was obtained for a hydroxylation with oleoyl-CoA as a substrate. The addition of NADH, necessary for the formation of ricinoleate, caused a decrease of the total radioactivity in PtdCho with a corresponding increase in the amount of label in free ricinoleic acid. This increase was due to the action of a phospholipase A, which released ricinoleic acid but not oleic acid from PtdCho. Such a phospholipase activity, attacking ricinoleoyl-PtdCho but not oleoyl-PtdCho, was also demonstrated in microsomal preparations from developing cotyledons of safflower and oil-seed rape. An analysis of the acyl groups at different positions in microsomal PtdCho of castor bean showed that ricinoleate was almost entirely associated with position sn-2. Likewise the [14C]ricinoleate in [14C]PtdCho formed after incubations with microsomal preparations with NADH and [14C]oleoyl-CoA resided in position sn-2 with none in position sn-1. In contrast, the [14C]linoleate formed by desaturation of [14C]oleoyl-PtdCho was present at both positions. In the presence of ATP, CoA and Mg2+, the ricinoleate acid released from PtdCho was activated to ricinoleoyl-CoA. The ricinoleoyl-CoA was an efficient acyl donor in the acylation of glycerol 3-phosphate (Gro3P) to yield phosphatidic acid and triacylglycerols. In microsomal preparations incubated with an equimolar mixture of [14C]oleoyl-CoA and [14C]ricinoleoyl-CoA in the presence of Gro3P, only a minor amount of [14C]ricinoleate entered PtdCho, and this was believed to be via the exchange of phosphocholine groups between a diacylglycerol pool and the PtdCho. On the basis of our results, a scheme of ricinoleate formation and its incorporation into triacylglycerols in castor-bean endosperm is proposed.

Adenosine Triphosphate↗
PubMed1991

Regulation of sterol biosynthesis in sunflower by 24(R,S),25-epiminolanosterol, a novel C-24 methyl transferase inhibitor.

Whereas sitosterol and 24(28)-methylene cycloartanol were competitive inhibitors (with Ki = 26 microM and 14 microM, respectively), 24(R,S)-25-epiminolanosterol was found to be a potent non-competitive inhibitor (Ki = 3.0 nM) of the S-adenosyl-L-methionine-C-24 methyl transferase from sunflower embryos. Because the ground state analog, 24(R,S)-oxidolanosterol, failed to inhibit the catalysis and 25-azalanosterol inhibited the catalysis with a Ki of 30 nM we conclude that the aziridine functions in a manner similar to the azasteriod (Rahier, A., et al., J. Biol. Chem. (1984) 259, 15215) as a transition state analog mimicking the carbonium intermediate found in the normal transmethylation reaction. Additionally, we observed that the aziridine inhibited cycloartenol metabolism (the preferred substrate for transmethylation) in cultured sunflower cells and cell growth.

Cell Division↗
PubMed1991

Thermal degradation of carotenes and influence on their physiological functions.

Raw carrot juice contains a considerable amount of alpha- and beta-carotene, which makes carrot an excellent source of vitamin A. Heat treatment of the juice at temperatures comparable to those at pasteurization and boiling does not change the carotenes, while heating at temperatures used during sterilization results in rearrangement of the carotene molecules and a decrease in total carotenes. The all-trans alpha- and beta-carotenes appear partly as cis-isomers, especially the 13-cis-isomer. Isomerization of the carotenes leads to a decrease in their vitamin A activity. Carotenes also seem to be anticarcinogens but the extent to which this property is influenced by isomerization is still unknown.

Beverages↗