Diagnosis of angiomyolipoma using computed tomography—region of interest ≤−10HU or 4 adjacent pixels ≤−10HU are recommended as the diagnostic thresholds

AIM

To study and compare the diagnostic accuracy of region of interest (ROI) density measurement and pixel mapping [computed tomography (CT) density of individual pixels] for the diagnosis of renal angiomyolipoma (AML) using CT.

MATERIALS AND METHODS

A study group of histologically proven AMLs was compared with a control group of histologically proven renal cell cancers, normal renal parenchyma, and simple renal cysts. The mean tissue density (ROI circle) and a pixel density map were recorded. The diagnostic accuracy of various thresholds of ROI and pixel mapping values were compared using receiver operating characteristic curves.

RESULTS

Twenty-two AMLs, 16 renal cell carcinomas (RCCs), 30 simple cysts, and 30 sites of renal parenchyma were evaluated. The mean (+/-1 SD) density of the AMLs was significantly lower [-15.2(20.8) units] than the three control groups [+36.0(8.1) units, +5.4(3.4) units and +22.2(46.5) units for RCC, renal cyst and parenchyma respectively; p < 0.001 (analysis of variance)]. The sensitivities and specificities of the ROI diagnostic thresholds of < or =0 units, < or =-10 units and < or =-20 units were 77 and 97%, 73 and 100% and 50 and 100%, respectively. Using pixel mapping [diagnostic thresholds of either a line of 4 pixels < or =-10 units or a square of 4 pixels < or =-10 units] the sensitivity improves to 86% with a specificity of 97%.

CONCLUSION

Although a ROI threshold value of < or =-10 units has a very high specificity (100% in the present study) the sensitivity is modest at only 73%. Pixel mapping is more sensitive for recognizing small clusters of fat. In practice, both methods can be recommended for the analysis of suspected AMLs. ROI density measurement is convenient when analysing large areas of suspected fat and < or =-10 units should be used as the diagnostic threshold. When faced with small lucent areas or indeterminate values after ROI analysis, pixel mapping is recommended using a line of 4 pixels < or =-10 units or a square of 4 pixels < or =-10 units as the discriminating thresholds.

Tuberose sclerosis complex: analysis of growth rates aids differentiation of renal cell carcinoma from atypical or minimal-fat-containing angiomyolipoma

AIM

To study the radiological characteristics of renal masses in individuals with tuberous sclerosis complex (TSC) using serial CT, and to examine how renal cell carcinoma (RCC) may be differentiated from indeterminate cysts or masses.

METHODS

This was a retrospective study of 12 cases of TSC in which dedicated renal CT followed after US had demonstrated cystic or sonographically unusual renal masses. The CT density of all masses was measured and the masses categorized as simple cysts, complex cysts, angiomyolipomas or indeterminate solid masses. Subjects were maintained on regular follow-up with repeat CT or MRI and interval renal US. Indeterminate masses that showed rapid growth were considered suspicious for renal cell carcinoma and biopsy or nephrectomy followed.

RESULTS

Comparative data were available for a median of 4 years. In each case the renal masses were multiple and bilateral; mean mass diameter was 3.6 cm. Among a total of 206 masses, 18 were simple cysts and 3 were complex cysts. Of the complex cysts, 1 proved to be an angiomyolipoma on histology and the other 2 showed no growth. Of the solid masses, 133 were typical angiomyolipomas (AMLs) and 52 were indeterminate. On follow-up, only 3 indeterminate masses showed rapid growth (>0.5 cm/year), of which only 1 proved to be an RCC on biopsy. The other 2 were minimal-fat AMLs, and the remainder of the masses showed no or slow growth.

CONCLUSION

Many renal masses associated with TSC are radiologically indeterminate. A growth threshold of >0.5 cm/year identified the only RCC in this study (0.5% of all masses). Yearly radiological follow-up of indeterminate renal masses is recommended for individuals with TSC.

Minor H antigens: genes and peptides

In this review, we describe the evidence from which the existence of non-MHC histocompatibility (H) antigens was deduced, the clinical setting of bone marrow transplantation in which they are important targets for T cell responses, and the current understanding of their molecular identity. We list the peptide epitopes, their MHC restriction molecules and the genes encoding them, of the human and murine minor H antigens now identified at the molecular level. Identification of the peptide epitopes allows T cell responses to these antigens following transplantation of MHC-matched, minor H-mismatched tissues to be enumerated using tetramers and elispot assays. This will facilitate analysis of correlations with HVG, GVH and GVL reactions in vivo. The potential to use minor H peptides to modulate in vivo responses to minor H antigens is discussed. Factors controlling immunodominance of T cell responses to one or a few of many potential minor H antigens remain to be elucidated but are important for making predictions of in vivo HVG, GVH and GVL responses and tailoring therapy after HLA-matched BMT and DLI.

The case of the midwife scientist

Genes controlling both testis determining and expression of the male-specific transplantation antigen, HY, are located on the short arm of the mouse Y chromosome, and on the X and Y-linked translocation, Sxr(a). A mutation of Sxr(a) was discovered in a cross between an Sxr carrier male and a T16H/X female. This was designated Sxr(b) and found to affect both the expression of HY and spermatogenesis, but not testis differentiation, thereby disproving Ohno's hypothesis that HY controlled testis determination. Molecular genetic analysis showed the mutation to be caused by fusion of two duplicated genes, Zfy1 and Zfy2, deleting the intervening DNA. This deletion interval, deltaSxr(b), contained a number of genes, each a candidate HY gene. Expression cloning with HY-specific T cell clones identified Smcy, Uty and Dby as encoding peptide epitopes of this transplantation antigen. The human homologues SMCY and UTY likewise express HY antigens and these are targets of damaging graft-versus-host (GVH) responses and potentially therapeutic graft-versus-leukaemia (GVL) responses following bone marrow transplantation (BMT). Knowledge of the peptide identity of HY epitopes allows monitoring of immune responses following BMT, using fluorescent tetramers, and also offers the possibility of inducing immunological tolerance.

Activation of HIV in human skin by ultraviolet B radiation and its inhibition by NFkappaB blocking agents

To determine whether ultraviolet B (UVB) irradiation leads to activation of HIV in human skin, we conducted prospective and controlled studies in two academic medical centers in Texas from July 1995 to April 1999. HIV-positive patients with UV-treatable skin diseases were enrolled at each center, 18 subjects at one and 16 at the other. In one center, specimens from lesional and nonlesional skin biopsies were taken before and after sham- or UVB-irradiation administered in vivo or in vitro. In the other center, UVB phototherapy was administered three times weekly and specimens from skin biopsies were taken before and after 2 weeks (six treatments). Cutaneous HIV load was assessed using reverse transcriptase-polymerase chain reaction and reverse transcriptase-polymerase chain reaction in situ hybridization. UVB irradiation led to a 6-10-fold increase in the number of HIV in skin. To ascertain a role for nuclear factor kappa B (NFkappaB) in UVB-inducible HIV activation, two types of blockers, NFkappaB oligonucleotide decoy and sodium salicylate, were tested; each inhibited UVB-inducible HIV activation in skin partially. We conclude that UVB irradiation leads to increased numbers of HIV in human skin via processes that include release of cytoplasmic NFkappaB.

Nitrogen cycling by wood decomposing soft-rot fungi in the "King Midas tomb," Gordion, Turkey

Archaeological wood in ancient tombs is found usually with extensive degradation, limiting what can be learned about the diet, environment, health, and cultural practices of the tomb builders and occupants. Within Tumulus Midas Mound at Gordion, Turkey, thought to be the tomb of the Phrygian King Midas of the 8th century B.C., we applied a stable nitrogen isotope test to infer the paleodiet of the king and determine the nitrogen sources for the fungal community that decomposed the wooden tomb, cultural objects, and human remains. Here we show through analysis of the coffin, furniture, and wooden tomb structure that the principal degrader, a soft-rot fungus, mobilized the king's highly (15)N-enriched nutrients, values indicative of a diet rich in meat, to decay wood throughout the tomb. It is also evident from the delta(15)N values of the degraded wood that the nitrogen needed for the decay of many of the artifacts in the tomb came from multiple sources, mobilized at potentially different episodes of decay. The redistribution of nutrients by the fungus was restricted by constraints imposed by the cellular structure of the different wood materials that apparently were used intentionally in the construction to minimize decay.

Minor H antigens: genes and peptides

In this review, we describe the evidence from which the existence of non-MHC histocompatibility (H) antigens was deduced, the clinical setting of bone marrow transplantation in which they are important targets for T-cell responses, and the current understanding of their molecular identity. We list the peptide epitopes of the human and murine minor H antigens now identified at the molecular level, their MHC restriction molecules and the genes encoding them. Identification of the peptide epitopes allows T-cell responses to these antigens following transplantation of MHC-matched, minor H-mismatched tissues to be enumerated using tetramers and elispot assays. This will facilitate analysis of correlations with host-versus-graft (HVG), graft-versus-host (GVH) and graft-versus-leukaemia (GVL) reactions in vivo. The potential to use minor H peptides to modulate in vivo responses to minor H antigens is discussed. Factors controlling immunodominance of T-cell responses to one or a few of many potential minor H antigens remain to be elucidated but are important for making predictions of in vivo HVG, GVH and GVL responses and tailoring therapy after HLA-matched bone marrow transplantation and donor lymphocyte infusion.

Examination of HY response: T cell expansion, immunodominance, and cross-priming revealed by HY tetramer analysis

We have applied MHC class I tetramers representing the two H2(b) MHC class I-restricted epitopes of the mouse male-specific minor transplantation Ag, HY, to directly determine the extent of expansion and immunodominance within the CD8+ T cell compartment following exposure to male tissue. Immunization with male bone marrow (BM), spleen, dendritic cells (DCs) and by skin graft led to rapid expansion of both specificities occupying up to >20% of the CD8+ T cell pool. At a high dose, whole BM or spleen were found to be more effective at stimulating the response than BM-derived DCs. In vivo, immunodominance within the responding cell population was only observed following chronic Ag stimulation, whereas epitope immunodominance was established rapidly following in vitro restimulation. Peptide affinity for the restricting MHC molecule was greater for the immunodominant epitope, suggesting that this might be a factor in the emergence of immunodominance. Using tetramers, we were able to directly visualize the cross-primed CD8+ HY response, but we did not find it to be the principal route for MHC class I presentation. Immunization with female spleen or DCs coated with the full complement of defined HY peptides, including the A(b)-restricted CD4+ Th cell determinant, failed to induce tetramer-reactive cells.

Rapid rejection of HLA-A2 transgenic skin graft due to indirect allorecognition

BACKGROUND

At present, it is not clear whether xenogeneic MHC molecules are recognized by T cells directly or indirectly through self-MHC-restricted presentation in a transplantation setting.

METHODS

We have transplanted skin from HLA-A2 transgenic (B6.A2) to nontransgenic C57BL/6 (B6) mice and investigated the subsequent mouse T-cell responses to HLA molecules, in vivo and in vitro.

RESULTS

Skin transplanted from transgenic B6.A2 to B6 mice was rejected rapidly, in 12-16 days. Although naive B6 mice did not respond to B6.A2 splenocytes in vitro, spleen cells from mice that underwent transplantation showed strong proliferative responses. An anti-B6.A2 T-cell line from mice that underwent transplantation made proliferative responses to B6.A2 splenocytes but did not recognize HLA-A2 on human cells or transfected allogeneic mouse cells. The indirect, self-H-2-restricted recognition of HLA-A2 implied by this was confirmed by the finding that lysates of HLA-A2-positive, but not HLA-A2-negative, human B cells were stimulatory when pulsed onto syngeneic antigen-presenting cells and by inhibition of anti-B6.A2 proliferation with both anti-mouse MHC class I and class II antibodies.

CONCLUSION

Our results suggest that indirect recognition of xenogeneic MHC antigen plays a predominant role in graft rejection.

Genetic analysis of a new mouse model for non-insulin-dependent diabetes

The TallyHo (TH) mouse strain is a newly established model for non-insulin-dependent diabetes mellitus (NIDDM). TH mice show obesity, hyperinsulinemia, hyperlipidemia, and male-limited hyperglycemia. A genetic dissection of the diabetes syndrome has been carried out using male backcross 1 progeny obtained from crosses between (C57BL/6J x TH)F1 and TH mice or (CAST/Ei x TH)F1 and TH mice. A genome-wide scan reveals three quantitative trait loci (QTLs), Tanidd1-3 (TH-associated NIDDM) linked to hyperglycemia. The major QTL (common in both crosses), Tanidd1, maps to chromosome (Chr) 19. Additionally, gene-gene interactions contributing to hyperglycemia have been observed between Tanidd1 and a locus on Chr 18 as well as between Tanidd2 and a locus on Chr 16. The overt hyperglycemia in TH mice is, therefore, likely due to a mutation in a major diabetes susceptibility locus on Chr 19, which interacts with additional genes to lead to an observable phenotype.

Buchu (Agathosma betulina and A. crenulata, Rutaceae) essential oils: their pharmacological action on guinea-pig ileum and antimicrobial activity on microorganisms

The mode of action of essential oils from two buchu species (Agathosma betulina and A. crenulata, Rutaceae) from the Cape region of South Africa has been studied on smooth muscle in-vitro using guinea-pig ileum. At high concentration, the oils had an initial spasmogenic activity followed by spasmolysis. The spasmolytic action was post-synaptic, not atropine-like and did not involve adrenoceptor or guanylyl cyclase activation. In the presence of the phosphodiesterase inhibitor rolipram, the spasmolytic action of A. betulina was significantly increased whilst that due to A. crenulata was also increased but not to a significant level. These results suggested a mode of action for the oils involving cyclic adenosine monophosphate. In addition, A. betulina appeared to block calcium channels but this was not seen with A. crenulata, possibly because the initial spasmogenic activity complicated the study of its spasmolytic action. Neither essential oil (10 microL, undiluted) demonstrated antimicrobial action against Enterococcus hirae and Pseudomonas aeruginosa but very low activity was observed against Escherichia coli, Saccharomyces cerevisiae and Staphylococcus aureus, suggesting little potential for these oils as antimicrobial agents/preservatives.

Low grade astrocytomas in the West of Scotland 1987-96: treatment, outcome, and cognitive functioning

BACKGROUND

Low grade astrocytomas are among the most common central nervous system tumours in children.

AIMS

To identify risk factors for the development of persistent intellectual handicap.

METHODS

The notes of 30 children with histologically proven low grade astrocytoma who presented during the period 1987-96 were reviewed. Thirteen of these children who were diagnosed with intracranial tumours between 1992 and 1996 underwent cognitive assessment one year after the completion of treatment.

RESULTS

Low grade astrocytomas were found in the cerebellum (59%), thalamus (17%), cerebral hemispheres (10%), and the cervical spinal cord (9%). Where possible all patients were treated with gross total resection of the tumour. Symptomatic children with tumours judged to be inoperable underwent biopsy followed by radiotherapy (13%). Three patients developed progressive disease following surgery and underwent repeat surgery and radiotherapy. Survival at a median follow up of 75 months (range 30-131) is 97%. At one year after the completion of treatment persisting cognitive impairment was common. The strongest predictor of IQ scores was the duration of symptoms of increased intracranial pressure preoperatively.

CONCLUSIONS

Although the overall survival rate of children with low grade astrocytoma is excellent, significant long term disability occurs. Early diagnosis is essential to reduce postoperative cognitive morbidity.

Gigantism due to growth hormone excess in a boy with optic glioma

True gigantism is rare in early childhood and is usually due to excess GH secretion from a pituitary adenoma. We report a case in which the endocrine abnormality is secondary to an optic glioma. Careful endocrine evaluation has shown that GH peak amplitude was not increased but rather there was failure of GH levels to suppress to baseline and a lack of pulsatility. There is no evidence of a direct secretory role for the tumour and we postulate that the tumour is affecting GH secretion through an effect on somatostatin tone. Specific tumour therapy is not indicated for this patient in the absence of mass effect or visual disturbance. The GH excess is being treated with somatostatin analogue (Octreotide) and as he has developed precocious puberty he is also receiving long acting GnRH analogue (Zoladex). This boy appears likely to have neurofibromatosis type 1 (NF1) which raises the question of subtle GH excess in NF1 patients with tall stature.

Booster seat use and reasons for nonuse

BACKGROUND

Many children 4 to 9 years old are inappropriately restrained in vehicles and are at risk for injury in crashes.

OBJECTIVES

This study was undertaken to determine the rate of booster seat use and the reasons for nonuse.

METHODS

Observations were conducted at a random sample of day care centers, and drivers of unrestrained children 4 to 8 years old were interviewed to determine the reasons for lack of booster seat use.

RESULTS

Observations were conducted on 149 children. Shoulder belt use significantly increased with the age of the child; 28.3% of 4-year-olds and 70.0% of 6- to 8-year-olds used lap-shoulder belts. Overall, 27.7% of children in the target age group used booster seats; only 10% of children 6 to 8 years old were restrained with booster seats. Booster seat use decreased when there were 3 or more passengers in the vehicle. The most common reason for lack of booster seat use was that parents thought the child was large enough to use the regular lap-shoulder belt system, or problems with attempting to use the seat in the vehicle. More than one half of parents who were not using booster seats at the time of the survey reported owning seats.

CONCLUSION

This study indicates that parental misconceptions about size and safety of regular restraint equipment are the most common reason that children are not appropriately restrained in vehicles. This information can be used to guide community intervention programs.