Deployment of an Interventional Radiology Telemedicine Program During the COVID-19 Pandemic: Initial Experience With 10,056 Visits

Objective

To evaluate the clinical, operational, and financial effects of using telemedicine services in an academic interventional radiology setting during the coronavirus disease 2019 pandemic and to identify potential barriers to equitable telemedicine access for patients.

Methods

Evaluation and management (E&M) data over a 104-week period from September 2019 to August 2021 were reviewed. Data related to the visits were recorded including visit type, billing provider, patient demographic information, Current Procedural Terminology code charged, and reimbursement received. The ZIP code pertaining to the patient’s primary residence was matched with median household income from the US Census Bureau.

Results

In all, 14,754 E&M encounters were performed over the study period, of which 10,056 were conducted using telemedicine. Twenty-two percent of visits were performed with interactive video; the remainder were performed using audio only. Female patients were more likely than male patients to use interactive video visits for telemedicine encounters (23.7% versus 20.4%, P < .001). Patients availing of video visits (mean age, 58.1 years, SD = 14.0) were also significantly younger than those patients who used audio-only (telephone) encounters (mean age, 62.5 years, SD = 13.3). Patients with private insurance and those living in neighborhoods with higher median household income were more likely to avail of interactive video visits (P < .001). Professional E&M monthly revenue was between 23.3% and 53.2% of peak prepandemic levels (mean 37.7%).

Conclusion

Telemedicine services allowed for rapid restoration of E&M encounter volumes over the study period. Further work is required to determine the potential implementation barriers to increasing the use of video visits.

Comparison of caudal tramadol versus caudal fentanyl with bupivacaine for prolongation of postoperative analgesia in pediatric patients

Background and Aims:

Caudal block is a common technique for pediatric analgesia for infraumblical surgeries. Because of the short duration of analgesia with bupivacaine alone various additive have been used to prolong the action of bupivacaine. The present study was aimed to evaluate the analgesic effect of tramadol or fentanyl added to bupivacaine for infraumblical surgeries in pediatric patients.

Materials and Methods:

We conducted a prospective, randomized, single-blind controlled trial. After written informed consent from parents, 100 patients belonging to American Society of Anesthesiologist physical status I-II, in the age group of 1-12 years, of either sex undergoing infraumblical surgery under general anesthesia were divided into two groups. Group BT received 1 ml/kg of 0.25% bupivacaine with tramadol 2 mg/kg in normal saline and Group BF received 1 ml/kg of 0.25% bupivacaine with fentanyl 2 μg/kg in normal saline with maximum volume of 12 ml in both groups. All patients were assessed intraoperatively for hemodynamic changes, the requirement of sevoflurane concentration, as well as postoperatively for pain by using FLACC (F = Face, L = Leg, A = Activity, C = Cry, C = Consolability), pain score and for sedation by using four point sedation score.

Results:

The mean duration of analgesia was 10–18 h in Group BT while in Group BF it was 7-11 h. The postoperatively period up to 1½ h, Group BF had higher sedation score up to two as compared to that below one on Group BT.

Conclusion:

Caudal tramadol significantly prolongs the duration of analgesia as compared to caudal fentanyl without any side effects.

Mangifera indica (mango)

Mangifera indica, commonly used herb in ayurvedic medicine. Although review articles on this plant are already published, but this review article is presented to compile all the updated information on its phytochemical and pharmacological activities, which were performed widely by different methods. Studies indicate mango possesses antidiabetic, anti-oxidant, anti-viral, cardiotonic, hypotensive, anti-inflammatory properties. Various effects like antibacterial, anti fungal, anthelmintic, anti parasitic, anti tumor, anti HIV, antibone resorption, antispasmodic, antipyretic, antidiarrhoeal, antiallergic, immunomodulation, hypolipidemic, anti microbial, hepatoprotective, gastroprotective have also been studied. These studies are very encouraging and indicate this herb should be studied more extensively to confirm these results and reveal other potential therapeutic effects. Clinical trials using mango for a variety of conditions should also be conducted.

Emerging oral anticoagulants for stroke prevention in patients with non-valvular atrial fibrillation

In patients with atrial fibrillation (AF) warfarin has been the mainstay therapy for stroke prevention. In recent randomized clinical trials (RCTs) oral direct thrombin inhibitor (Dabigatran) and factor Xa inhibitors (Rivaroxaban and Apixaban) challenged the efficacy and safety benchmarks set by warfarin. These drugs boast a rapid onset of action, shorter half-life and fewer drug and dietary interactions. Moreover, these new anticoagulants do not require monitoring, titration or dose adjustments. These agents have already been approved for prevention of stroke or systemic embolism in patients with AF. Uncertainty regarding suitability, efficacy and safety in certain patient subsets and issues related to the ability effectively monitor the pharmacodynamic effects and reverse the therapeutic effects of these drugs should be addressed as we engage in a widespread use of these agents in various patient subsets.

Mechanisms of potentiation of Angiotensin II-induced contractile response of isolated rat aorta by hydrogen peroxide and tert-butyryl hydroperoxide

Objective:

To study the mechanism involved in hydrogen peroxide (H₂O₂) or tert-butyl hydroperoxide (t-BHP)-induced potentiation of the Ang II-mediated contraction of isolated rat thoracic aorta.

Materials and Methods:

Thoracic aorta was isolated from the Sprauge dawley rats (300–320 gm), cut spirally and response to Ang II (5 × 10⁻⁸M) was taken in the absence and presence of H₂O₂ (10⁻⁶M) and t-BHP (10⁻⁵M). To explore the probable mechanism of H₂O₂ and t-BHP-induced potentiation of Ang II-mediated contractile response, different blockers such as losartan (AT₁ receptor blocker; 1 μM), catalase (H₂O₂ scavenger; 500 U/ml), lercanidipine (L-type calcium channel blocker; 1 μM), geinistein (tyrosine kinase inhibitor; 100 μM), and indomethacin (cyclo-oxygenase inhibitor; 10 μM) were used.

Results:

In spiral preparation of rat thoracic aorta, H₂O₂ (10⁻⁶M) and t-BHP (10⁻⁵M) did not produce the contraction as such. However, when they are added simultaneously with Ang II (5 × 10⁻⁸ M), they potentiated the contractile response of the Ang II. Catalase (500 U/ml) partially antagonized the Ang-II-induced contraction, as well as antagonized the potentiation induced by H₂O₂. Losartan (1 μM) and lercanidipine (1 μM) antagonized the Ang II-induced contractile response without affecting H₂O₂ (10⁻⁶M)-mediated potentiation. Geinistein (100 μM) antagonized H₂O₂ (10⁻⁶M)-mediated potentiation, but it slightly decreased the Ang II response. Losartan (1 μM) and lercanidipine (1 μM) and Geinistein (100 μM) antagonized the Ang II-induced contractile response but not t-BHP-mediated potentiation. Indomethacin antagonized t-BHP-mediated potentiation without affecting much of Ang II response.

Conclusion:

From the above-mentioned results, we can reasonably conclude that H₂O₂ and t-BHP potentiated the contraction induced by the Ang II. H₂O₂-induced potentiation of Ang II response may be mediated through tyrosine kinase activation and t-BHP through the activation of cyclo-oxygenase enzyme.

Genotype-phenotype correlation in British families with X linked congenital stationary night blindness

AIM

To correlate the phenotype of X linked congenital stationary night blindness (CSNBX) with genotype.

METHODS

11 CSNB families were diagnosed with the X linked form of the disease by clinical evaluation and mutation detection in either the NYX or CACNA1F gene. Phenotype of the CSNBX patients was defined by clinical examination, psychophysical, and standardised electrophysiological testing.

RESULTS

Comprehensive mutation screening identified NYX gene mutations in eight families and CACNA1F gene mutations in three families. Electrophysiological and psychophysical evidence of a functioning but impaired rod system was present in subjects from each genotype group, although the responses tended to be more severely affected in subjects with NYX gene mutations. Scotopic oscillatory potentials were absent in all subjects with NYX gene mutations while subnormal OFF responses were specific to subjects with CACNA1F gene mutations.

CONCLUSIONS

NYX gene mutations were a more frequent cause of CSNBX than CACNA1F gene mutations in the 11 British families studied. As evidence of a functioning rod system was identified in the majority of subjects tested, the clinical phenotypes "complete" and "incomplete" do not correlate with genotype. Instead, electrophysiological indicators of inner retinal function, specifically the characteristics of scotopic oscillatory potentials, 30 Hz flicker and the OFF response, may prove more discriminatory.

A clinical and molecular genetic study of a rare dominantly inherited syndrome (MRCS) comprising of microcornea, rod-cone dystrophy, cataract, and posterior staphyloma

AIM

To phenotype and genetically map the disease locus in a family presenting with autosomal dominant microcornea, rod-cone dystrophy, cataract, and posterior staphyloma.

METHODS

Six affected and three unaffected members of the pedigree were examined. All individuals provided a history and underwent a full clinical examination with A-scan and B-scan ultrasonography and electrophysiological testing where appropriate. PCR based microsatellite marker genotyping using a positional candidate gene approach was then performed on DNA samples extracted from venous blood provided by each subject.

RESULTS

The disorder is inherited as an autosomal dominant trait with variable expressivity and has a complex phenotype. Affected individuals had bilateral microcornea, pulverulent-like lens opacities, a rod-cone dystrophy and posterior staphyloma (MRCS). Using a positional candidate gene approach, the authors have evidence suggestive of linkage of this disorder to a region on 11q13 within the nanophthalmos 1 (NNO1) genetic interval. The small family size militates against achieving a LOD score of 3, but the haplotype data and the position of the putative MRCS locus within a known nanophthalmos locus are suggestive of linkage. A candidate gene within this region (ROM1) was screened and no mutations were found in affected members of the family.

CONCLUSION

This rare developmental disorder has some phenotypic similarities to nanophthalmos and possibly maps to a locus within the genetic interval encompassing the NNO1 locus. Screening of candidate genes within this region continues.

Isolation and characterization of the human homeobox gene HOX D1

Homeobox genes, first identified in Drosophila, encode transcription factors that regulate embryonic development along the anteroposterior axis of an organism. Vertebrate homeobox genes are described on the basis of their homology to the genes found within the Drosophila Antennapedia and Bithorax homeotic gene complexes. Mammals possess four paralogous homeobox (HOX) gene clusters, HOX A, HOX B, HOX C and HOX D, each located on different chromosomes, consisting of 9 to 11 genes arranged in tandem. We report the characterization of the human HOX D1 gene. This gene consists of two exons, encoding a 328 amino acid protein, separated by an intron of 354 bp. The human HOX D1 protein is one amino acid longer (328 amino acids) than the mouse protein (327 amino acids) and is 82% identical to the mouse HOX D1 homolog. The DNA binding homeodomain region of the human protein exhibits a 97% and 80% identity between mouse Hoxd1 and Drosophila labial homeodomains, respectively. The exon/intron and intron/exon splice junctions are conserved in position between human and mouse genes. Determination of the human HOX D1 gene structure permits the use of PCR based analysis of this gene for the assessment of mutations, for diseases that link to the HOXD cluster (such as Duanes Retraction Syndrome (DRS)), or polymorphisms associated with human variation. Molecular characterization of the HOXD1 gene may also permit analysis of the functional role of this gene in human neurogenisis.

A novel keratocan mutation causing autosomal recessive cornea plana

PURPOSE

Mutations in keratocan (KERA), a small leucine-rich proteoglycan, have recently been shown to be responsible for cases of autosomal recessive cornea plana (CNA2). A consanguineous pedigree in which cornea plana cosegregated with microphthalmia was investigated by linkage analysis and direct sequencing.

METHODS

Linkage was sought to polymorphic microsatellite markers distributed around the CNA2 and microphthalmia loci (arCMIC, adCMIC, NNO1, and CHX10) using PCR and nondenaturing polyacrylamide gel electrophoresis before KERA was directly sequenced for mutations.

RESULTS

Positive lod scores were obtained with markers encompassing the CNA2 locus, the maximum two-point lod scores of 2.18 at recombination fraction theta = 0 was obtained with markers D12S95 and D12S327. Mutation screening of KERA revealed a novel single-nucleotide substitution at codon 215, which results in the substitution of lysine for threonine at the start of a highly conserved leucine-rich repeat motif. Structural modeling predicts that the motifs are stacked into an arched beta-sheet array and that the effect of the mutation is to alter the length and position of one of these motifs.

CONCLUSIONS

This report describes a novel mutation in KERA that alters a highly conserved motif and is predicted to affect the tertiary structure of the molecule. Normal corneal function is dependent on the regular spacing of collagen fibrils, and the predicted alteration of the tertiary structure of KERA is the probable mechanism of the cornea plana phenotype.

The prehospital electrocardiogram

Although widely used in Europe, the prehospital 12-lead electrocardiogram (EKG) has seen only limited use in this country. Reported benefits of the 12-lead EKG include shortening the door-to-needle time, accelerating the initiation of reperfusion therapy, and overall improving the prehospital and hospital management and outcome of patients with acute myocardial infarction. The field EKG also provides the basis for prehospital fibrinolysis. Concerns still exist, however, regarding the best means of providing real-time field interpretation of the prehospital EKG and the potential for inappropriate field time delay, triage, and treatment of patients. Moreover, questions remain about the overall clinical and cost benefit of expanding this resource universally. The following article reviews the role of prehospital EKG in caring for patients with acute coronary syndromes.

Randomized, placebo-controlled trial of oral phytonadione for excessive anticoagulation

STUDY OBJECTIVE

To compare the efficacy of managing excessive anticoagulation in the absence of bleeding by either omitting warfarin therapy alone or administering oral phytonadione in addition to omitting warfarin therapy.

DESIGN

Randomized, double-blind, placebo-controlled study.

SETTING

Clinical pharmacy anticoagulation service in a group model health maintenance organization.

SUBJECTS

Thirty nonbleeding patients with international normalized ratios (INRs) ranging from 6.0-10.0.

INTERVENTIONS

Patients were randomized to receive either a single oral dose of phytonadione 2.5 mg or placebo. Both groups omitted warfarin doses until the INR became less than or equal to 4.0.

MEASUREMENTS AND RESULTS

The mean calculated time to reach an INR of 4.0 was significantly greater in the placebo than the phytonadione group (2.6 vs 1.4 days, p=0.006). Overcorrection of anticoagulation was significantly more common in patients receiving phytonadione. Overt warfarin resistance was not observed in either group after reinitiating warfarin therapy. No major bleeding or thromboembolic complications occurred, and minor bleeding episodes were similar in both groups.

CONCLUSION

The addition of oral phytonadione 2.5 mg reduced the time to achieve an INR of 4.0 by approximately 1 day compared with omitting warfarin therapy alone. Adverse events did not differ between the two groups. Both strategies were effective in managing asymptomatic patients with INRs of 6.0-10.0. Oral phytonadione may be most appropriate for patients at high risk for bleeding in whom the benefit of prompt INR reduction would outweigh the thromboembolic risk associated with INR overcorrection.

A novel mutation in the Norrie disease gene

Norrie disease is an X-linked recessive disorder characterized by congenital blindness and in some cases mental retardation and deafness.(1) The variability of signs among patients often complicates diagnosis. Signs such as an ocular pseudoglioma, progressive deafness, and mental disturbance are considered classic features.(2) Only one third of patients with Norrie disease have sensorineural deafness, and approximately one half of the affected individuals exhibit mental retardation, often with psychotic features.(3) Histologic analysis has suggested that retinal dysgenesis occurs early in eye development and involves cells in the inner wall of the optic cup.(4) The gene associated with Norrie disease was identified in 1992. (5,6) We report a novel mutation identified in a patient in whom Norrie disease was diagnosed.

DNA-based diagnosis of the von Hippel-Lindau syndrome

PURPOSE

To evaluate the etiology of a unilateral hemangioblastoma noted in a male with a family history remarkable only for spine surgery in the proband's father.

METHODS

Genomic DNA was isolated from peripheral blood of family members, and the three exons of the von Hippel-Lindau gene were examined for mutations by direct sequencing.

RESULTS

A three base pair (bp) deletion in exon 1 of the VHL gene was found in the father and both sons. This in-frame deletion results in the loss of a phenylalanine residue from the von Hippel-Lindau protein product, at amino acid position 76.

CONCLUSION

Genetic screening has confirmed that von Hippel-Lindau syndrome is responsible for the hemangioblastoma in the proband. Magnetic resonance imaging scans performed as a consequence of these results indicated spinal tumors present in the father and tumors present in the cerebellum of the proband's sibling. As close, lifelong follow-up is warranted with this disease, this case demonstrates the value of DNA testing in patients with ocular findings consistent with von Hippel-Lindau disease in the absence of a recognized family history.

Localization of a gene for Duane retraction syndrome to chromosome 2q31

Duane retraction syndrome (DRS) is a congenital eye-movement disorder characterized by a failure of cranial nerve VI (the abducens nerve) to develop normally, resulting in restriction or absence of abduction, restricted adduction, and narrowing of the palpebral fissure and retraction of the globe on attempted adduction. DRS has a prevalence of approximately 0.1% in the general population and accounts for 5% of all strabismus cases. Undiagnosed DRS in children can lead to amblyopia, a permanent uncorrectable loss of vision. A large family with autosomal dominant DRS was examined and tested for genetic linkage. After exclusion of candidate regions previously associated with DRS, a genomewide search with highly polymorphic microsatellite markers was performed, and significant evidence for linkage was obtained at chromosome 2q31 (D2S2314 maximum LOD score 11.73 at maximum recombination fraction. 0). Haplotype analysis places the affected gene in a 17.8-cM region between the markers D2S2330 and D2S364. No recombinants were seen with markers between these two loci. The linked region contains the homeobox D gene cluster. Three of the genes within this cluster, known to participate in hindbrain development, were sequenced in affected and control individuals. Coding sequences for these genes were normal or had genetic alterations unlikely to be responsible for the DRS phenotype. Identifying the gene responsible for DRS may lead to an improved understanding of early cranial-nerve development.

Impact of therapeutic interchange from pravastatin to lovastatin in a Veterans Affairs Medical Center

OBJECTIVE

To evaluate the impact of a therapeutic interchange from pravastatin to lovastatin on treatment outcomes, quality of life, patient satisfaction, and costs.

STUDY DESIGN

A prospective cohort study of 170 patients switched from pravastatin to lovastatin from September 1997 through November 1997.

PATIENTS AND METHODS

The therapeutic interchange program promoting lovastatin as the preferred agent went into effect June 2, 1997 after Merck & Co. was awarded the Veterans Health Administration national contract for 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors. Patients were switched to lovastatin by either their primary care physician during routine clinic visits or the pharmacist by mail. The following outcomes were measured before and after conversion to lovastatin: lipid values, liver function tests, National Cholesterol Education Program (NCEP) low-density cholesterol (LDL-C) goals achieved, quality of life (QOL) (measured by the Medical Outcomes Study 36-item short-form health survey [SF-36]), medication tolerance (measured with a global symptom survey), patient satisfaction, and cost-minimization analysis.

RESULTS

Lipid values and liver function test results were similar for pravastatin and lovastatin treatment. Forty percent of patients achieved NCEP LDL-C goals before and after formulary conversion. There were no significant differences between pravastatin and lovastatin in QOL, medication tolerance, and patient satisfaction. The projected cost savings from this therapeutic interchange was approximately $211,000 annually.

CONCLUSION

Therapeutic interchange from pravastatin to lovastatin resulted in substantial cost savings. QOL, patient satisfaction, and achievement of NCEP LDL-C goals were maintained.

Asymptomatic shedding of herpes simplex virus from the genital tract: uncertainty and its consequences for patient management. The Herpes Simplex Virus Advisory Panel

A frequent component of the management of patients with genital herpes concerns the possibility of asymptomatic shedding and potential sexual transmission of the virus. Approaches intended to provide supportive counselling and reassurance of patients about these issues need now to be modified in the light of increasing data of the frequency of asymptomatic detection of virus and the effects of antiviral therapy on this phenomenon. Further studies to delineate the relationship between asymptomatic detection of HSV in the genital tract and the mechanism of sexual transmission of this virus need to be conducted before clinicians instigate antiviral suppressive treatment primarily to prevent sexual transmission of HSV. However, it is important that the new data and our greater understanding of the natural history of genital herpes is translated into accurate and comprehensible information for our patients.

Regional assignment of 30 expressed sequence tags on human chromosome 7 using a somatic cell hybrid panel

The regional assignments of 30 expressed sequence tags (ESTs) on human chromosome 7 were determined by studying the segregation of their PCR-amplified products in a panel of mouse somatic cell hybrids. ESTs are important molecular landmarks for physical mapping and can be considered as tags to candidate genes for genetically linked human inherited diseases. These results contribute further potential gene sequences to the transcriptional map of chromosome 7.

A YAC contig spanning the dominant retinitis pigmentosa locus (RP9) on chromosome 7p

The dominant retinitis pigmentosa locus RP9 has previously been localized to 7p13-p15, in the interval D7S526-D7S484. We now report refinement of the locus to the interval D7S795-D7S484 and a YAC contig of approximately 4.8 Mb spanning this region and extending both distally and proximally from it. The contig was constructed by STS content mapping and physically orders 29 STSs in 28 YAC clones. The order of polymorphic markers in the contig is consistent with a genetic map that has been assembled using haplotype data from the CEPH pedigrees. This contig will provide a primary resource for the construction of a transcriptional map of this region and for the identification of the defective gene causing this form of adRP.

Hopelessness predicts future depressive symptoms: a prospective analysis of cognitive vulnerability and cognitive content specificity

Beck's content specificity hypothesis predicts distinct cognitive content within specific psychological disorders. We evaluated whether the third component of the "cognitive triad", negative view of the future (hopelessness), would be related 4 weeks later to depressive symptoms, but not to anxiety. University student participants (83 females, 71 males) were tested on the Beck Depression Inventory and the Beck Anxiety Inventory at two points in time, separated by 4 weeks. The Hopelessness Scale was administered at time 1 and a Life Events Inventory at time 2. Concurrent cognitive content specificity was replicated. For males only, hopelessness predicted future depression severity scores, but not anxiety. Hopelessness predicted depressive symptoms over and above life event stressors, but not vice versa.

Detection of Cryptosporidium parvum DNA in fixed, paraffin-embedded tissue by the polymerase chain reaction

The objective of this project was to demonstrate detection of Cryptosporidium parvum DNA in fixed, paraffin-embedded tissue using the polymerase chain reaction (PCR). DNA was purified from six samples of fixed, paraffin-embedded tissue that were histologically positive for C. parvum and used in the PCR. Previously developed oligonucleotide primers specific for C. parvum were used to amplify a 452-base target sequence, and a 20-base synthetic probe labeled with digoxigenin-11-dUTP was used to detect the amplification product by chemiluminescence. All six samples were positive by PCR; negative controls showed no amplification or hybridization. This approach could provide a sensitive and specific method for detection of parasite material in fixed, paraffin-embedded tissue samples, and prove to be of significant value in retrospective studies of archival material.

DNA sequences for the specific detection of Cryptosporidium parvum by the polymerase chain reaction

The objective of this project was to construct specific and sensitive molecular probes and amplification primers for Cryptosporidium parvum that could be used in diagnosis, retrospective tissue studies, and in epidemiologic surveys. Whole genomic DNA was extracted from oocysts of C. parvum purified from human and bovine feces. A genomic library was constructed in plasmid pUC18 and propagated in Escherichia coli DH5 alpha. Transformants were screened by colony hybridization and autoradiography. The 2.3-kilobase segment in plasmid pHC1, a clone specific for C. parvum, was sequenced by the Sanger method. Computer analysis gave a G+C content of 35%. A 400-base region (bases 470-870) was selected as an amplification target because it contained a unique restriction endonuclease site that could serve as a useful marker. Primers of 26 nucleotides each were synthesized. Sensitive and specific amplification of the target sequence was demonstrated both by ethidium bromide staining of agarose and acrylamide gels, and by hybridization with chemiluminescence-labeled synthetic oligonucleotide probes.

Detection of untreated mycobacteria by using polymerase chain reaction and specific DNA probes

A method for specific identification of mycobacteria by using the polymerase chain reaction on organisms taken from liquid cultures, frozen suspensions, or colonies grown on Lowenstein-Jensen slants is presented. This direct detection of mycobacterial organisms has important implications for strain typing and diagnosis.

Genus- and species-specific DNA probes to identify mycobacteria using the polymerase chain reaction

Differential diagnosis of Mycobacterium tuberculosis, M. avium, and other mycobacteria remains a lengthy process. Recently, the use of DNA probes has been proposed as a new approach for a more specific and rapid diagnosis. Here, we report the cloning and sequencing of a genus-specific probe for Mycobacterium and a species-specific M. avium probe. The genus-specific probe hybridizes with DNA from nine ATCC type strains and 13 isolates of mycobacteria but not to non-mycobacterial DNA. In addition, the cloned fragment could also be amplified by polymerase chain reaction (PCR) in DNa of ten different mycobacterial type strains. The M. avium specific probe hybridizes strongly to sequences amplified in M. avium but not other mycobacterial or non-mycobacterial DNA. Amplification of the target sequence by PCR allowed the detection of 1 fg of all mycobacterial DNA tested for the genus-specific probe and 1 fg of M. avium DNA for the species-specific probe.

Sequence analysis and amplification by polymerase chain reaction of a cloned DNA fragment for identification of Mycobacterium tuberculosis

Analysis of the 1,016-base-pair sequence of a putative probe for identification of Mycobacterium tuberculosis revealed two almost identical fragments of 507 and 509 bases. From this sequence two pairs of primers were synthesized (MtbAB and MtbCD), ranging from 18 to 22 nucleotides, for use in polymerase chain reactions (PCRs) with DNA from six reference strains of M. tuberculosis, as well as type strains of M. bovis, M. bovis BCG, M. kansasii, M. avium, M. intracellulare, and M. scrofulaceum. Although there was amplification of DNA from all mycobacterial strains included in the study, when used as probes, a predominant band, fragment CD from M. tuberculosis H37Rv DNA, proved to be more specific for strains of M. tuberculosis than the original probe, pMTb4, was. Amplified fragments from as little as 1 fg of DNA (equivalent to one-fifth of an organism) could be resolved on ethidium bromide-stained gels loaded with a 1/10 volume of PCR. Furthermore, it was possible to amplify specific DNA sequences from frozen M. tuberculosis H37Rv organisms which were thawed prior to PCR.

A cloned DNA fragment for identification of Mycobacterium tuberculosis

The identification of Mycobacterium tuberculosis is a lengthy process. Attempts were made to develop a more rapid, specific, and sensitive assay for identifying tubercle bacilli in biologic specimens by differentially screening plasmid libraries of Sau3AI-digested M. tuberculosis H37Rv (ATCC 25618) DNA with homologous and heterologous DNA for clones that hybridized strongly with M. tuberculosis DNA alone. Three clones, pMTB1, pMTb2, and pMTb3, were selected for further study. Southern analysis indicated that these clones reacted strongly with DNA from strains of M. tuberculosis isolated in different parts of the world, weakly with DNA from other mycobacterial species, and not at all with Escherichia coli or human DNA. Smaller fragments of mycobacterial DNA contained in plasmid pMTb3 were subcloned into pBR322 (pMTb4) or pUC12 (pMTb5). These recombinant plasmids hybridized with DNA from M. tuberculosis, Mycobacterium bovis, and Mycobacterium bovis BCG (bacille Calmette-Guérin) Montreal and may provide the reagents needed for the development of new methods for rapid diagnosis of M. tuberculosis infections.

Difficulties and complications of the Ender method of treatment of trochanteric fractures of the femur

The advantages of the Ender technique over the other methods of treatment of trochanteric fractures of the femur have been emphasized by several authors but the difficulties and complications of the method have perhaps not been sufficiently highlighted. With this imbalance in mind, 60 patients treated by the Ender method have been reviewed with particular emphasis on the problems encountered during treatment. The follow-up period ranges from 6 to 28 months. The main technical difficulties were experienced during the reduction and nailing of the comminuted and displaced fracture. The main postoperative complications were the cutting out of the nails from the head and neck fragment with weight bearing, backing down of the nails at the knee, and external rotation deformity. The early mortality, infection, delayed union and non-union rates were low.