Challenges of Childhood TB/HIV Management in Malawi

The diagnosis and management of childhood tuberculosis (TB) are major challenges in countries such as Malawi with high incidence of TB and human immunodeficiency virus (HIV) infection. Diagnosis of TB in children often relies only on clinical features but clinical overlap with the presentation of HIV and other HIV-related lung disease is common. The tuberculin skin test (TST), the standard marker of M. tuberculosis infection in immune competent children, has poor sensitivity in HIV-infected children and is not usually available in Malawi. HIV test should be routine in children with suspected TB as it improves clinical management. HIV-infected children are at increased risk of developing active disease following TB exposure which justifies the use of isoniazid preventive therapy (IPT) once active disease has been excluded but this is difficult to implement and appropriate duration of IPT is unknown. HIV-infected children with active TB experience higher mortality and relapse rates on standard TB treatment compared to HIV-uninfected children, highlighting the need for further research to define optimal treatment regimens. HIV-infected children should also receive appropriate supportive care including cotrimoxazole prophylaxis and anti-retroviral treatment (ART) if indicated. There are concerns about concurrent use of some anti-TB drugs such as rifampicin with some ARTs.     

Comparison of Phaconit Rollable IOL with Acrylic Foldable IOL

Background

Phaconit or ultra micro incision phacoemulsification cataract surgery involves phacoemulsification through a 0.9 millimetre sleeveless phaco tip and irrigating chopper followed by implantation of a rollable intraocular lens. The procedure leads to negligible astigmatism and faster visual recovery as compared to phacoemulsification with a foldable intraocular lens.

Methods

This prospective study analysed 80 cases of sub millimetre phaconit surgery with implantation of rollable intraocular lenses(IOL) in 40 cases and acrylic foldable IOL in the remaining 40 cases. Evaluation of efficacy and adaptability of procedure, equipment settings, operative constraints, postoperative complications, keratometric and topographic evaluation of induced astigmatism with visual outcome and patient''s rehabilitation were studied.

Results

The intraoperative complications were surge/ chamber collapse in 16 (20%), iris chaffing in one and corneal burns in two cases. All cases had an induced astigmatism of less than or equal to ± 0.25 D in four to six weeks after rollable IOL and ± 0.5 D to ± 0.75 D after acrylic IOL implantation. All patients had best-corrected visual acuity of 6/6 by third post operative day.

Conclusion

Phaconit with rollable IOL is a perfect blend of surgical skill, application of technology and ultra thin IOL.Key Words: Phaconit, Ultra micro phaco, Submillimetre incision, Rollable IOL implantation     

膝关节周围骨肿瘤手术的肢体康复

0　引言　膝关节周围是骨原发恶性肿瘤的好发部位 .病变组织广泛侵袭 ,切除肿瘤造成骨与软组织缺损 ,各种重建方法都需最大限度地保留膝关节功能 .如何采取早期系统的康复治疗 ,是临床骨肿瘤保肢手术的重要内容 .1　对象和方法　 1992 - 0 5 / 1999- 0 3,膝关节周围恶性骨肿瘤患者 6 4例接受保肢手术治疗 .男 38例 ,女 2 6例 ;骨肉瘤 5 2例 ,恶性骨巨细胞瘤 5例 ,尤文瘤 3例 ,母细胞瘤 2例 ,原发神经外胚层肿瘤 2例 .手术方式 :异体半关节移植术 37例 ;异体骨段移植术 16例 ;复合异体骨段的人工全膝关节表面置换术3例 ,动力旋转铰链式人工全…     

Monoclonal antibodies selected to discriminate between malignant melanomas and nevocellular nevi

Two monoclonal antibodies (MoAbs), PAL-M1 and PAL-M2, are described that were selected to discriminate between melanomas and nevocellular nevi (NN) in frozen sections. MoAb PAL-M1 reacted with all 15 melanoma metastases (MM), with 14 of 19 primary cutaneous melanomas (PCM), 9 of 35 dysplastic nevi (DN), and 2 of 26 NN. The 2 NN stained were removed from patients with the dysplastic nevus syndrome. MoAb PAL-M2 reacted with 9 of 15 MM, 5 of 19 PCM, 3 of 35 DN, and did not react with 26 NN after usual staining conditions. The proportion of melanocytic cells stained was low in DN and much higher in PCM and especially in MM. Staining in DN was restricted to intraepidermal or subepidermal nests of atypical melanocytes. In PCM, staining with PAL-M2 was observed only in tumors with a Breslow thickness of 0.76 mm or higher. PAL-M1 and PAL-M2 may be immunohistochemical markers for tumor progression in melanocytic proliferations.     

Analysis of major histocompatibility antigens and the mononuclear cell infiltrate in halo nevi

A series of monoclonal antibodies was used to characterize the nevomelanocytes and the inflammatory infiltrate of 11 halo nevi in different stages of resolution, employing an immunoperoxidase technique. Three of the 11 halo nevi histologically showed signs of mild or moderate nevomelanocytic atypia. It was found that the vast majority of the nevomelanocytes in halo nevi with a dense inflammatory infiltrate markedly expressed HLA-A,B,C antigens, while expression was not demonstrable in nevocellular nests not adjacent to the mononuclear infiltrate. No difference in expression of HLA-A,B,C antigens was found between the 3 cases with mild or moderate nevomelanocytic atypia and the other cases lacking atypia. Expression of HLA-DR (Ia-like) antigens was found on few nevomelanocytes in only 2 of 11 lesions. The cellular composition of the mononuclear inflammatory infiltrate showed a predominance of T cells (80% or more) with a relatively high proportion of cytotoxic/suppressor T cells. Most of the T cells showed signs of activation as judged by staining for HLA-DR antigens. These results demonstrate that the expression of HLA-A,B,C antigens on the nevomelanocytes and the cellular composition of the mononuclear inflammatory infiltrate in halo nevi are very similar to that in malignant melanomas and dysplastic neiv. These findings also indicate the expression of HLA-A,B,C antigens on nevomelanocytes is primarily dependent on the presence of T-cell immune response and not necessarily related to the presence of nevomelanocytic atypia.     

Staphylococcus saprophyticus in males with symptoms of chronic prostatitis

Staphylococcus saprophyticus was isolated in 17 percent (12 of 71 men) during one year, but with a peak in August and September to 21 percent in patients referred to the urology department with a suspicion of chronic bacterial prostatitis. Seven of the 12 men had S. saprophyticus in highest number at the prostatic level. Three of these were designated as chronic bacterial prostatitis. In this study the occurrence of S. saprophyticus appears to follow, and possibly depends on, previous antibiotic therapy. S. saprophyticus disappeared without treatment in all cases.     

Human telomerase RNA component expression in Spitz nevi,common melanocytic nevi,and malignant melanomas

BACKGROUND: Telomerase is a ribonucleoprotein DNA polymerase that is capable of synthesizing telomeres onto the ends of chromosomes. The cumulative loss of telomerase activity is believed to be associated with cell senescence. Telomerase activity has been shown to be higher in malignant melanomas than in common melanocytic nevi. The aim of the present study was to elucidate the pattern of expression of the human telomerase RNA (hTER) component in routinely processed specimens of Spitz nevi, malignant melanomas, and ordinary melanocytic nevi. METHODS: Ten specimens of each type of tumor were studied, using an in situ hybridization technique. RESULTS: All three types of tumors demonstrated moderate to high intensities of hTER expression, usually in more than half of the tumor cells, and the majority of the studied lesions in each group did not show stratification of staining. The hTER component was also detected in the epidermis, sweat glands, and pilosebaceous units. CONCLUSIONS: hTER levels do not necessarily correlate with the level of telomerase activity, and the level and pattern of hTER expression are not useful as an adjunct to the histologic differential diagnosis of Spitz nevi from melanocytic nevi and malignant melanomas.     

V-region mutation in vitro,in vivo,and in silico reveal the importance of the enzymatic properties of AID and the sequence environment

The somatic hypermutation of Ig variable regions requires the activity of activation-induced cytidine deaminase (AID) which has previously been shown to preferentially deaminate WRC (W = A/T, R = A/G) motif hot spots in in vivo and in vitro assays. We compared mutation profiles of in vitro assays for the 3′ flanking intron of VhJ558-Jh4 region to previously reported in vivo profiles for the same region in the Msh2^−/−Ung^−/− mice that lack base excision and mismatch repair. We found that the in vitro and in vivo mutation profiles were highly correlated for the top (nontranscribed) strand, while for the bottom (transcribed) strand the correlation is far lower. We used an in silico model of AID activity to elucidate the relative importance of motif targeting in vivo. We found that the mutation process entails substantial complexity beyond motif targeting, a large part of which is captured in vitro. To elucidate the contribution of the sequence environment to the observed differences between the top and bottom strands, we analyzed intermutational distances. The bottom strand shows an approximately exponential distribution of distances in vivo and in vitro, as expected from a null model. However, the top strand deviates strongly from this distribution in that mutations approximately 50 nucleotides apart are greatly reduced, again both in vivo and in vitro, illustrating an important strand asymmetry. While we have confirmed that AID targeting of hot and cold spots is a key part of the mutation process, our results suggest that the sequence environment plays an equally important role.     

Rare recombination events generate sequence diversity among balancer chromosomes in Drosophila melanogaster

Multiply inverted balancer chromosomes that suppress exchange with their homologs are an essential part of the Drosophila melanogaster genetic toolkit. Despite their widespread use, the organization of balancer chromosomes has not been characterized at the molecular level, and the degree of sequence variation among copies of balancer chromosomes is unknown. To map inversion breakpoints and study potential diversity in descendants of a structurally identical balancer chromosome, we sequenced a panel of laboratory stocks containing the most widely used X chromosome balancer, First Multiple 7 (FM7). We mapped the locations of FM7 breakpoints to precise euchromatic coordinates and identified the flanking sequence of breakpoints in heterochromatic regions. Analysis of SNP variation revealed megabase-scale blocks of sequence divergence among currently used FM7 stocks. We present evidence that this divergence arose through rare double-crossover events that replaced a female-sterile allele of the singed gene (sn^X2) on FM7c with a sequence from balanced chromosomes. We propose that although double-crossover events are rare in individual crosses, many FM7c chromosomes in the Bloomington Drosophila Stock Center have lost sn^X2 by this mechanism on a historical timescale. Finally, we characterize the original allele of the Bar gene (B¹) that is carried on FM7, and validate the hypothesis that the origin and subsequent reversion of the B¹ duplication are mediated by unequal exchange. Our results reject a simple nonrecombining, clonal mode for the laboratory evolution of balancer chromosomes and have implications for how balancer chromosomes should be used in the design and interpretation of genetic experiments in Drosophila.Balancer chromosomes are genetically engineered chromosomes that suppress crossing over with their homologs and are used for many purposes in genetics, including construction of complex genotypes, maintenance of stocks, and estimation of mutation rates. Balancers typically carry multiple inversions that suppress genetic exchange or result in the formation of abnormal meiotic products if crossing over does occur (Fig. 1A); for example, single crossovers inside the inverted segment create acentric or dicentric chromosomes that will fail to segregate properly during meiosis or large deletions or duplications that will likely result in inviable gametes (1, 2). Balancers also often carry recessive lethal or sterile mutations to prevent their propagation as homozygotes as well as dominant markers for easy identification. First developed for use in Drosophila melanogaster, balancer chromosomes remain some of the most powerful tools for genetic analysis in this species (3).Open in a separate windowFig. 1.Consequences of a single or double crossover between a WT X chromosome and an X chromosome carrying a single inversion, In(1)dl-49. Euchromatin is shown in blue, heterochromatin is shown in gray, and centromeres are depicted as circles. Thin white lines mark locations of inversion breakpoints, and yellow crosses/thin lines mark locations of crossover events. (A) A single crossover event within the inverted segment results in the formation of chromosomes with deletions and zero (acentric) centromeres or duplications and two (dicentric) centromeres, neither of which will segregate properly during meiosis. (B) A double crossover within an inverted segment results in intact chromosomes with one centromere that will segregate properly during meiosis.Despite their widespread use, very little is known about the organization of Drosophila balancer chromosomes at the molecular level. Since their original syntheses decades ago, balancers have undergone many manipulations, including the addition or removal of genetic markers. Moreover, rare recombination events can cause spontaneous loss of deleterious alleles on chromosomes kept over balancers in stock, as well as loss of marker alleles on balancer chromosomes themselves (3). Likewise, recent evidence has shown that sequence variants can be exchanged between balancer chromosomes and their wild type (WT) homologs via gene conversion during stock construction or maintenance (4, 5). Thus, substantial variation may exist among structurally identical balancer chromosomes owing to various types of sequence exchange.To gain insight into the structure and evolution of balancer chromosomes, we have undertaken a genomic analysis of the most commonly used X chromosome balancer in D. melanogaster, First Multiple 7 (FM7). We have focused on FM7 because this X chromosome balancer series lacks lethal mutations and thus can be easily sequenced in a hemizygous or homozygous state. In addition, the FM7 chromosome has been shown to pair normally along most of its axis with a standard X chromosome, providing a structural basis for possible exchange events (6). Moreover, although details of how early balancers in D. melanogaster were created are not fully recorded, the synthesis and cytology of the FM7 series is reasonably well documented (3).The earliest chromosome in the FM7 series, FM7a, was constructed using two progenitor X chromosome balancers, FM1 and FM6, to create a chromosome carrying three inversions—In(1)sc⁸, In(1)dl-49, and In(1)FM6—relative to the WT configuration (7, 8) (Fig. 2A). Subsequently, a female-sterile allele of singed (sn^X2) was introduced onto FM7a to create FM7c, which prevents the loss of balanced chromosomes carrying recessive lethal or female-sterile mutations (9). More recently, versions of FM7a and FM7c have been generated that carry transgene insertions that allow the determination of balancer genotypes in embryonic or pupal stages (10–14).Open in a separate windowFig. 2.Structure of the FM7 balancer chromosome. Euchromatin is shown in blue, and heterochromatin is shown in gray. (A) Schematic view of the organization of WT and FM7 X chromosomes. FM7 contains three inversions—In(1)sc⁸, In(1)dl-49, and In(1)FM6—relative to WT. The six breakpoint junctions for the three inversions are numbered 1–6 and are shown in detail in B. (B) Location and organization of inversion breakpoints in FM7. Each inversion has two breakpoints that can be represented as A/B and C/D in the standard WT arrangement and as A/C and B/D in the inverted FM7 arrangement, where A, B, C, and D represent the sequences on either side of the breakpoints. Locations of euchromatic breakpoints are on Release 5 genome coordinates, and the identity of the best BLAST match in FlyBase is shown for heterochromatic sequences. Primers used for PCR amplification are shown above each breakpoint; details are provided in Methods and Datasets S2 and S3. Forward and reverse primers are named with respect to the orientation of the assembled breakpoint contigs, not the orientation of the WT or FM7 X chromosome.To identify the inversion breakpoints in FM7 balancers and to study patterns of sequence variation that may have arisen since the origin of the FM7 series, we sequenced genomes of eight D. melanogaster stocks carrying the FM7 chromosome (four FM7a and four FM7c). We discovered several megabase-scale regions in which FM7c chromosomes differ from one another, which presumably arose via double-crossover (DCO) events from balanced chromosomes (Fig. 1B). These DCOs eliminate the female-sterile sn^X2 allele in the centrally located In(1)dl-49 inversion and are expected to confer a fitness advantage to sn⁺ chromosomes, either by allowing propagation of sn⁺ FM7 as homozygotes in females or by sn⁺ FM7 males outcompeting sn^X2 FM7 males in culture. We found that loss of the sn^X2 allele is common in FM7c chromosomes by screening other FM7c-carrying stocks at the Bloomington Drosophila Stock Center. We also identified the breakpoints of the B¹ duplication carried on FM7, and found direct molecular evidence for the role of unequal exchange in the origin and reversion of the B¹ allele (15–19). Our results provide clear evidence that the common assumption that balancers are fully nonrecombining chromosomes is incorrect on a historical timescale, and that substantial sequence variation exists among balancer chromosomes in circulation today.