The potential for utilising in-hospital glucose measurements to detect individuals at high risk of previously undiagnosed diabetes: Retrospective cohort study.

BACKGROUND: Many people with undiagnosed diabetes have hyperglycaemia when admitted to hospital. Inpatient hyperglycaemia can be an indication of diabetes mellitus but can also indicate a stress response. This study reports the extent to which an in-hospital maximum observed random glucose measurement is an indicator of the need for in-hospital (or subsequent) HbA1c measurement to look for undiagnosed diabetes. METHODS: Blood glucose, HbA1c, age and sex were collected for all adults following admission to a UK NHS trust hospital from 1 January 2019 to 31 December 2020. We restricted the analysis to those participants who were registered with a GP practice that uses the trust laboratory and who had at least some tests requested by those practices since 2008. We stratified individuals according to their maximum in-hospital glucose measurement and report the number of these with HbA1c measurement ≥48 mmol/mol (6.5%) prior to the index admission, and during and after admission. We calculated an estimated proportion of individuals in each blood glucose stratum without a follow-up HbA1c who could have undiagnosed diabetes. RESULTS: In toal, 764,241 glucose measurements were recorded for 81,763 individuals who were admitted to the Oxford University Hospitals Trust. The median (Q1, Q3) age was 70 (56, 81) years, and 53% were males. Of the population, 70.7% of individuals declared themselves to be of White ethnicity, 3.1% of Asian background, and 1.1% of Black background, with 23.1% unstated. Of those individuals, 22,375 (27.4%) had no previous HbA1c measurement recorded. A total of 1689 individuals had a diabetes-range HbA1c during or after their hospital admission (2.5%) while we estimate an additional 1496 (2.2%) may have undiagnosed diabetes, with the greatest proportion of these having an in-hospital glucose of ≥15 mmol/L. We estimate that the number needed to detect a possible new case of diabetes falls from 16 (in-hospital glucose 8 mmol/L to <9 mmol/L) to 4 (14 mmol/L to <15 mmol/L). CONCLUSION: The number of people who need to be tested to identify an individual who may have diabetes decreases as a testing threshold based on maximum in-hospital glucose concentration increases. Among those with hyperglycaemia and no previous HbA1c measurement in the diabetes range, there appears to be a lack of subsequent HbA1c measurement. This work identifies the potential for integrating the testing and follow-up of people, with apparently unrecognised hospital hyperglycaemia across primary and secondary care.

Anti-Trypanosoma brucei activity in Cape buffalo serum during the cryptic phase of parasitemia is mediated by antibodies.

Cape buffalo are reservoir hosts of African trypanosomes. They rapidly suppress population growth of the highly antigenically variable extracellular haemoprotozoa and subsequently maintain a cryptic infection. Here we use in vitro cultures of trypanosomes cloned from Cape buffalo blood during cryptic infection, as well as related and unrelated trypanosomes, to identify anti-trypanosome components present in cryptic-phase infection serum. Trypanosome clone-specific complement-dependent trypanolytic IgM and IgG arose after appearance of target trypanosomes during cryptic infection. Serum collected late in the cryptic phase of infection contained complement-independent growth-inhibitory IgG which varied in activity among target trypanosomes. Removal of protein A/G-binding IgG from the serum restored its capacity to support trypanosome growth in vitro. Recovered growth-inhibitory IgG reacted with the variable surface glycoprotein (VSG) of parasites most affected by it, and reacted with trypanosome common antigens, notably the endosome-restricted tomato lectin-binding glycoproteins (TL-antigens). The inclusion of purified TL-antigens in culture medium did not affect the trypanosome growth-inhibitory activity of immune Cape buffalo serum. In addition, hyperimmune rabbit IgG against TL-antigens showed little or no binding to intact trypanosomes and did not affect trypanosome growth in vitro although it did react strongly with TL-antigens and trypanosome endosomes. We conclude that antibodies, particularly clone-specific (putatively VSG-specific) antibodies are responsible for the anti-trypanosome activity of cryptic phase infection serum consistent with a dominant role in parasite control in Cape buffalo.

The African trypanosome cyclophilin A homologue contains unusual conserved central and N-terminal domains and is developmentally regulated.

We have cloned and characterized the homologue of cyclophilin A (CypA) from Trypanosoma brucei brucei, Trypanosoma congolense, Trypanosoma evansi and Trypanosoma vivax. The 1-kilobase African trypanosome CypA complementary DNA contains an open reading frame of 531 base pairs, corresponding to 177 amino acids with a calculated molecular weight of 18,700. The CypA gene is present at one copy/haploid genome in T. brucei, T. congolense and T. vivax and is located on large chromosomes (>3 Mb) in T. brucei. CypA is differentially transcribed in African trypanosomes and is localized in the cytosol as well as in the flagellum. It is also detected in the supernatant of in vitro cultivated parasites. The African trypanosome CypA is unique due to a ten amino acid residue N-terminus extension and a block that includes a three amino acid insertion around position 100 that might result in a differently structured surface. Wild-type recombinant CypA and several mutants were over-expressed in Escherichia coli and purified to >98% homogeneity. Antisera from cattle immunized with a trypanosome fraction containing immunosuppressive activity react strongly against CypA. These data indicate that trypanosome CypA might play an important role in the establishment and maintenance of infections in susceptible animals.

Serum xanthine oxidase: origin, regulation, and contribution to control of trypanosome parasitemia.

African trypanosomiasis is caused by Salivarian trypanosomes, tsetse fly-transmitted protozoa that inhabit the blood plasma, lymph and interstitial fluids, and, in the case of Trypanosoma brucei species, also the cerebrospinal fluid of mammal hosts. Trypanosomiasis in people and domestic animals manifests as recurring waves of parasites in the blood and is typically fatal. In contrast, trypanosomiasis in Cape buffaloes, which are naturally selected to resist the disease, is characterized by the development of only one or a few waves of parasitemia, after which the infection becomes cryptic, being maintained by the presence of 1-20 mammal-infective organisms/ml of blood. The control of the acute phase of parasitemia in Cape buffaloes correlates with a decline in blood catalase activity and the generation of trypanocidal H(2)O(2) in serum during the catabolism of endogenous purine by xanthine oxidase. Here we review features of this response, and of trypanosome metabolism, that facilitate H(2)O(2)-mediated killing of the parasites with minimal damage to the host. We also discuss the origin and regulation of serum xanthine oxidase and catalase, and show how recovery of serum catalase in infected Cape buffaloes precludes a role for H(2)O(2) in the long-term, stable suppression of trypanosome parasitemia.

Characterisation of the QM gene of Trypanosoma brucei.

The QM protein has been reported to have roles in both tumour suppression and transcription factor regulation in vertebrate cells, and in ribosome stability in both yeast and mammals. The present study isolated the QM gene of Trypanosoma brucei and determined its sequence. Alignment with QM sequences from Saccharomyces cerevisiae, Arabidopsis thaliana, Drosophila melanogaster and Homo sapiens revealed greater than 60% identity. Southern blot analysis revealed multiple copies of QM within the trypanosome genome. An epitope tag was inserted into the C-terminus of the T. brucei QM and the protein expressed under inducible control in procyclic form trypanosomes. Immune fluorescence microscopy revealed co-localisation with the GPI:protein transamidase component, GPI8, a distribution indicative of ribosome association with the rough endoplasmic reticulum.

Trypanosoma brucei: composition, organisation, plasticity, and differential transcription of NlaIII repeat elements in drug-resistant and sensitive isolates.

A Trypanosoma brucei brucei DNA repeat sequence termed NlaIII repeat (NR) was originally isolated from a multidrug-resistant field isolate CP547 [Jamnadass, R., 1995. Identification and characterisation of an extrachromosomal element from a multidrug-resistant isolate of T. brucei brucei, Ph.D. thesis, Brunel University, UK]. Subsequently studied in a laboratory strain (Tb427) [Alsford, N.S., Navarro, M., Jamnadass, H.R., Dunbar, H., Ackroyd, M., Murphy, N.B., Gull, K., Ersfeld,K., 2003. The identification of circular extrachromosomal DNA in the nuclear genome of T. brucei. Molecular Microbiology 47, 277-288], NRs were exclusively episomal. Here we show that NR sequences in CP547 are present on linear chromosomes as well as on episomal circular elements. Sequence analysis shows that NRs are composed of three classes of sub-repeat arranged in a specific order. Heterogeneity in size and sequence of an episomal 6.6kbp element was shown in successive passages of the original CP547 isolate and derived clones in mice. Its copy number was unstable and was affected by selective pressure with the trypanocide diminazene aceturate. Some of the extrachromosomal elements appear to be composed of RNA-DNA hybrids. NR sequences were transcribed in a developmentally regulated manner but transcripts did not contain the spliced-leader sequence found on all trypanosome mRNAs.

Recombinant tumor necrosis factor alpha does not inhibit the growth of African trypanosomes in axenic cultures.

Mice whose tumor necrosis factor alpha (TNF-alpha) genes were disrupted developed higher levels of parasitemia than wild-type mice following infection with Trypanosoma congolense IL1180 or T. brucei brucei GUTat3.1, confirming the results of earlier studies. To determine whether TNF-alpha directly affects the growth of these and other bloodstream forms of African trypanosomes, we studied the effects of recombinant mouse, human, and bovine TNF-alpha on the growth of two isolates of T. congolense, IL1180 and IL3338, and two isolates of T. brucei brucei, GUTat3.1 and ILTat1.1, under axenic culture conditions. The preparations of recombinant TNF-alpha used were biologically active as determined by their capacity to kill L929 cells. Of five recombinant TNF-alpha lots tested, one lot of mouse TNF-alpha inhibited the growth of both isolates of T. brucei brucei and one lot of bovine TNF-alpha inhibited the growth of T. brucei brucei ILTat1.1 but only at very high concentrations and without causing detectable killing of the parasites. The other lots of mouse recombinant TNF-alpha, as well as human TNF-alpha, did not affect the growth of any of the test trypanosomes even at maximal concentrations that could be attained in the culture systems (3,000 to 15,000 U of TNF-alpha/ml of medium). These results suggest that exogenously added recombinant TNF-alpha generally does not inhibit the growth of African trypanosomes under the culture conditions we used. The impact of TNF-alpha on trypanosome parasitemia may be indirect, at least with respect to the four strains of trypanosomes reported here.