Biomedical subjects
Publications and source records attributed to L Lindahl.
Two copies of the structural gene for the elongation factor EF-Tu have been identified in Escherichia coli: one near rif and the other near str. The latter seems to belong to a single transcriptional unit together with the genes for ribosomal protein S7, S12 (str) and the elongation factor EF-G (fus).
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Specialized lambda transducing phages have been isolated carrying approximately half the ribosomal protein genes of E. coli. These phages carry regions of the bacterial chromosome between aroE and fus. The ribosomal protein genes on these phages have been identified by the stimulation of ribosomal protein synthesis in ultraviolet-irradiated bacteria following infection by the transducing phage, and by the in vitro synthesis of ribosomal proteins in a DNA-dependent protein synthesizing system. The results indicate lambdadspcl probably carries at least 22 ribosomal protein genes and lambdadspc2 at least 26 genes. All these genes are clustered between trkA and strA. At least 13 of them have not been previously mapped.
The transducing phage lambdarifd18 isolated by Kirschbaum and Konrad [(1973 J. Bacteriol. 116, 517-526] was found to carry structural genes for several 50S ribosomal proteins and 16S and 23S rRNA. It has previously been demonstrated [Kirschbaum & Scaife (1974) Mol. Gen. Genet. 132, 193-201] that this phage carries genes for the DNA-dependent RNA polymerase (nucleosidetriphosphate:RNA nucleotidyltransferase; EC 2.7.7.6) subunits beta and beta'. Thus, the region of the E. coli chromosome carried by lambdarifd18 contains a cluster of genes essential for transcription and translation.
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RNase MRP is a ribonucleoprotein enzyme with a structure similar to RNase P. It is required for normal processing of precursor rRNA, cleaving it in the Internal Transcribed Spacer 1.
We have cloned the L4 ribosomal protein genes from Morganella morganii and Haemophilus influenza. The sequences of these genes were compared with published sequences for Escherichia coli, Yersinia pseudotuberculosis, and Bacillus stearothermophilus. All five of these L4 genes were expressed in E. coli and shown to function as repressors of both transcription and translation of the E. coli S10 operon. Possible implications for regulation of r-protein synthesis in species other E. coli are discussed.
By a careful ENT and oral examination of 111 patients with suspected chronic maxillary sinusitis, the diagnosis was verified in only 56% (62/111). In 29 of these 62 patients (47%) a relation to dental infections was found, periodontitis being as frequent as apical granulomas. In 61% of the patients, in whom the diagnosis chronic maxillary sinusitis could not be verified, dental infections and/or myofascial pain dysfunction syndrome (MPD) were the most common and likely cause of the symptoms. A careful oral examination including dental radiographs is thus important in patients with chronic maxillary sinusitis.
The diagnostic criteria and the length of the observation period are essential factors influencing the results of treatment of maxillary sinusitis. In 198 patients (244 sinuses) with chronic maxillary sinusitis of either rhinogenous or dental etiology all patients were judged as cured or improved at the short-term control 1-3 months after completion of therapy. The long-term observation (mean 3.5 years) revealed different figures of healing. Satisfactory results after conservative therapy were seen in only 34% while the Caldwell-Luc operation gave good results in 80%. In sinusitis of dental origin, dental treatment combined with local sinus surgery was successful in 90%. In 78 sinuses investigated by sinoscopy, discrepancy between the symptoms and the endoscopic findings was seen in 14 cases (18%). Information obtained by questionnaire is therefore unreliable. In 30 sinuses operated upon with the Caldwell-Luc procedure, discrepancy between radiographic and endoscopic findings was seen in 3 cases (10%). Contributory factors, e.g. nasal polyps, dental infections and nasal allergy were found in 48 out of 84 sinuses not completely healed at the long-term control. Patients treated for chronic maxillary sinusitis must be followed up over a long period. A clinical control after 1-2 years, including sinoscopy or sinus radiographs, is recommended even in patients free from symptoms of sinusitis. Sinoscopy seems to be more reliable than sinus radiography and should be performed if the sinus radiographs show any pathology. The patients are also recommended to visit their dentists regularly, due to the close relationship between dental infections and chronic maxillary sinus diseases.
In a long-term follow-up study (mean 3.5 years) after treatment of chronic maxillary sinusitis of either rhinogenous or dental origin, 72 sinuses in 66 patients were examined with respect to maxillo-ostial and nasal resistance. In sinusitis of rhinogenous etiology, the mean equivalent ostial diameter was pathologically narrowed (0.89 mm, in patients treated conservatively) whereas it was normal (2.51 mm) in sinusitis of dental etiology (dental treatment in combination with local sinus surgery). In the former group, all sinuses were diseased, compared with 3 out of 23 in the dental group. In order to distinguish between functional and organic ostial stenosis, the patients were also tested after physical exercise. The functional ostial diameter in healthy sinuses was significantly increased in contrast to the diseased sinuses. In one patient the narrow ostium was due to mucosal swelling only, but in the other cases was caused mainly by an organic stenosis. In sinusitis of rhinogenous etiology, a pathologically increased nasal resistance was found in 14.3%, while the corresponding figure in the dental group was 4.3%. Improved sinusal and nasal ventilation, achieved either pharmacologically or, preferably by surgical intervention, seems necessary for successful treatment of chronic maxillary sinusitis.
Various definitions have been proposed for the term 'chronic sinusitis' but too often reports on chronic sinusitis lack a definition. In order to improve the diagnosis and treatment of this disease, and also to facilitate comparisons between clinical investigations, definitions of 'chronic maxillary sinusitis' of either rhinogenous or dental origin are proposed. It is suggested that the differential diagnosis should be based upon the duration of symptoms, ENT and dental examinations, sinus radiographs and/or sinoscopy, and results of conservative treatment. In a study conducted over a 5-year period, 198 patients with 244 affected sinuses fulfilled the proposed criteria. The incidence of chronic maxillary sinusitis in the population was 0.02%. A dental cause was found in 40.6% of the sinuses. The dental cause could be confirmed by routine dental examination in only 43 of 99 cases, while an extended maxillo-dental examination was conclusive in the other cases (56/99). Marginal periodontitis was found as frequently as periapical granuloma and together they constituted 83% of all dental causes. Sinusitis of dental origin was rare before the age of 30. Every sixth patient was found to have nasal polyposis. When related to the number of affected sinuses, the incidence of nasal polyposis was 13.1% in sinusitis of dental origin and 23.4% in that of rhinogenous origin. The importance of close cooperation between the ENT specialist and the oral surgeon is stressed.