Operative management of non-elective incisional hernia reduces readmission in a national database.

PURPOSE: The aim of this project was to compare patient characteristics, overall efficacy, and readmission events following operative vs non-operative management modalities of non-elective patients presenting with symptomatic incisional hernias. METHODS: This study is a retrospective study of patients and patient demographics that presented as non-elective hospitalizations with symptomatic incisional hernia. Analysis of patients and characteristics utilized the National Readmission Database from 2010 to Q3 of 2015, delineating patient factors and outcomes following operative or non-operative management of hernias. RESULTS: A total of 14,137 patients met inclusion criteria for our study. The majority of patients were treated operatively rather than non-operatively (79 vs. 21%) on their non-elective admission for incisional hernia. Those undergoing surgical management were younger (56 vs 61 years, p < 0.01), we more often of male gender (69 vs 64%, p < 0.01), and had fewer comorbidities (1.92 vs 2.97, p < 0.01) and chronic conditions (0.45 vs 2.68, p < 0.01). Patients managed operatively had a significantly lower readmission rate when compared to patients managed non-operatively (6.6 vs 14.3%, p < 0.01). However, non-operative management was associated with a shorter length of stay (3 vs 4 days, p < 0.01). Of patients who were initially medically managed and had to be readmitted, a further 61% underwent surgical treatment on their readmission. CONCLUSION: In this nationwide study, patients with non-elective admissions for incisional hernia were mostly managed surgically. Those managed operatively had lower rates of readmission when compared to non-operative management. Initial non-operative management was associated with a shorter length of stay and a lower cost to the patient. The results of this study support operative management of symptomatic incisional hernia.

Surgical and non-surgical treatment of inguinal hernia during non-elective admissions in the Nationwide Readmissions Database.

INTRODUCTION: Inguinal hernia repair is one of the most common surgical operations, yet the optimal treatment strategy remains undefined. Treatment of symptomatic inguinal hernias include both surgical and non-surgical approaches. The objective of this study was to determine differences in population, readmission rates, and costs between operative and non-operative approaches for patients admitted non-electively for an inguinal hernia in a national dataset. In addition, we sought to define the baseline characteristics of the two groups and identify potential predictive factors in the non-surgically managed subgroup who were readmitted and treated operatively within 90 days of their first visit. METHODS: This study was a retrospective review of data from the Nationwide Readmissions Database (NRD) from 2010 to 2014. Patients above age 18 who were admitted non-electively for a primary diagnosis of inguinal hernia were included. Patients whose length of stay was < 1% or > 95% percentile or died during the initial visit were excluded. Readmissions within 90 days of the initial visit were flagged. Patients were classified according to initial management strategy: operative versus non-operative. Demographic, clinical, and organizational characteristics were compared between the two cohorts. RESULTS: 14,249 patients met inclusion criteria and were operative (n = 8996, 63.13%) and non-operative (n = 5255, 36.88%) cohorts. When comparing the two groups, readmission rate was lower (0.49% for surgical, 1.78% for non-surgical, p < 0.01), mean length of stay (LOS) longer (3.27 [SE = 0.05] days for surgical, 2.76 days [SE = 0.06] for non-surgical, p < 0.01), and mean total cost higher ($9597 for surgical, $7167 for non-surgical, p < 0.01) in surgically treated patients. The non-surgical population was on average older (63.05 years for surgical, 64.52 years for non-surgical, p < 0.01) with more chronic conditions (3.57 for surgical, 4.05 for non-surgical, p < 0.01). Of the patients initially managed non-surgically, 1.78% (n = 91) were readmitted, and of them, 62.63% (n = 57) were readmitted and managed surgically within 90 days of initial admission (i.e., crossed over from watchful waiting to surgical treatment). Average number of chronic conditions (3.79 versus 4.03, p = 0.74), average number of comorbidities (2.26 versus 2.18, p = 0.87), and average total number of ICD-9 discharge codes (7.44 versus 8.23 p = 0.54 did not differ significantly between the operative versus non-operative sample of the readmitted population. The total cost ($5562.38 versus $8737.28, p = 0.01) was greater in the operative versus non-operative sample. CONCLUSION: Watchful-waiting strategy is the most common treatment approach in patients admitted non-electively for symptomatic inguinal hernia. Readmission after non-elective hospitalization for inguinal hernia is rare, but surgical intervention decreased the likelihood of readmission compared to non-operative management, while also increasing LOS and cost of care. Our data supports a patient centric approach to the management; non-surgical treatment is a viable temporary option even in symptomatic inguinal hernias, while surgical treatment may reduce the likelihood of future readmission.

Protein expression studies of desmoplakin mutations in cardiomyopathy patients reveal different molecular disease mechanisms.

Mutations in the gene for desmoplakin (DSP) may cause arrhythmogenic right ventricular cardiomyopathy (ARVC) and Carvajal syndrome (CS). Desmoplakin is part of all desmosomes, which are abundantly expressed in both myocardial and epidermal tissue and serve as intercellular mechanical junctions. This study aimed to investigate protein expression in myocardial and epidermal tissue of ARVC and CS patients carrying DSP mutations in order to elucidate potential molecular disease mechanisms. Genetic investigations identified three ARVC patients carrying different heterozygous DSP mutations in addition to a homozygous DSP mutation in a CS patient. The protein expression of DSP in mutation carriers was evaluated in biopsies from myocardial and epidermal tissue by immunohistochemistry. Keratinocyte cultures were established from skin biopsies of mutation carriers and characterized by reverse transcriptase polymerase chain reaction, western blotting, and protein mass spectrometry. The results showed that the mutation carriers had abnormal DSP expression in both myocardial and epidermal tissue. The investigations revealed that the disease mechanisms varied accordingly to the specific types of DSP mutation identified and included haploinsufficiency, dominant-negative effects, or a combination hereof. Furthermore, the results suggest that the keratinocytes cultured from patients are a valuable and easily accessible resource to elucidate the effects of desmosomal gene mutations in humans.

Molecular autopsy in young sudden cardiac death victims with suspected cardiomyopathy.

The aim of this investigation was to identify and characterise pathogenic mutations in a sudden cardiac death (SCD) cohort suspected of cardiomyopathy in persons aged 0-40 years. The study material for the genetic screening of cardiomyopathies consisted of 41 cases and was selected from the case database at the Institute of Forensic Medicine. Mutational screening by DNA sequencing was performed to detect mutations in DNA samples from deceased persons suspected of suffering from hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM), and arrhythmogenic right ventricle cardiomyopathy (ARVC). A total of 9 of the examined 41 cases had a rare sequence variant in the MYBPC3, MYH7, LMNA, PKP2 or TMEM43 genes, of which 4 cases (9.8%) were presumed to be pathogenic mutations. The presumed pathogenic mutations were distributed with one case of suspected HCM and DCM (MYH7; p.R442H), one case of suspected DCM (LMNA; p.R471H), and two cases of suspected ARVC (PKP2; p.R79X and LMNA; p.R644C). The presented data adds important information on the genetic elements of SCD in the young, and calls for expert pathological evaluation and molecular autopsy in the post-mortem examination of SCD victims with structural anomalies of the heart.

Hyponatremia as a prognostic and predictive factor in metastatic renal cell carcinoma.

BACKGROUND: Low serum sodium has recently been associated with poor survival in localised renal cell carcinoma (RCC). We now show the prognostic effect of serum sodium in patients with metastatic RCC (mRCC). METHODS: Cohort A comprised 120 consecutive patients with mRCC receiving subcutaneous, low-dose interleukin-2 and interferon-alpha. Hyponatremia was assessed in univariate and multivariate analyses. An independent cohort of another 120 patients with mRCC was used for validation (cohort B). RESULTS: In cohort A, estimated 5-year survival was 15% and median survival was 15.1 months. Serum sodium ranged between 126 and 144 mM. Twenty-four patients (20%) had serum sodium levels below normal range (<136 mM). In multivariate analysis, significant independent risk factors for short survival were low serum sodium (P=0.014), high neutrophils (P=0.018), lactate dehydrogenase >1.5 upper normal level (P=0.002), and number of metastatic sites (+3) (P=0.003). In cohort B, serum sodium ranged between 128 and 146 mM. Seventeen patients (14%) had sodium levels below normal range. In multivariate analysis, serum sodium was validated as an independent prognostic factor (P=0.001). A significant association between lack of response and hyponatremia was observed in both cohorts (P=0.003 and P=0.02, respectively). CONCLUSION: Low serum sodium is a new, validated, independent prognostic, and predictive factor in patients with mRCC.

LDL receptor mutation genotype and vascular disease phenotype in heterozygous familial hypercholesterolaemia.

Patients with homozygous familial hypercholesterolaemia (FH) caused by receptor-negative, low-density lipoprotein (LDL) receptor gene mutations have higher concentrations of LDL-cholesterol in plasma and earlier onset of cardiovascular disease (CVD) than patients homozygous for receptor-defective, LDL receptor mutations. In contrast, it is uncertain whether the severity of atherosclerotic disease differs in heterozygous FH caused by receptor-negative and receptor-defective mutations. The present authors investigated the influence of LDL receptor mutation type on the clinical phenotype in 31 patients with heterozygous FH caused by the receptor-negative, Trp23-stop mutation and in 31 patients heterozygous for the receptor defective Trp66-Gly mutation. Untreated levels of plasma LDL-cholesterol and calculated cholesterol-years score did not differ significantly between the two groups of patients. Detection of vascular disease was based on two approaches: (1) measurement of coronary calcification by spiral computed tomography (CT) scanning; and (2) ultrasonic measurement of carotid intima-media thickness (IMT). Age was significantly correlated to the presence of coronary calcification, but controlling for relevant cofactors, there was no evidence that the receptor-negative mutation caused more calcification than the receptor-defective mutation. Furthermore, carotid IMT was significantly influenced by plasma concentrations of Lp(a) and triglycerides, as well as by age, sex and smoking status, but again, there was no statistically significant effect of LDL receptor gene mutational type. The similarity in vascular phenotypes was probably caused by a similar life-long burden of LDL-cholesterol in the two groups of patients.

Four-strand hamstring tendon autograft compared with patellar tendon-bone autograft for anterior cruciate ligament reconstruction. A randomized study with two-year follow-up.

Seventy-two patients with subacute or chronic rupture of the anterior cruciate ligament were randomly assigned to autograft reconstruction with four-strand gracilis and semitendinosus tendon (N = 37) or with patellar tendon-bone (N = 35) from the ipsilateral side. The groups were similar in terms of age, sex, level of activity, degree of laxity, meniscal lesions found surgically, and rehabilitation program. The follow-up was performed at another hospital by independent observers after 6, 12, and 24 months. Sixty-one patients (32 with hamstring tendon grafts and 29 with patellar tendon grafts) complied with the follow-up routine for the full 24 months. No differences were found between the groups with respect to Cincinnati functional score, KT-1000 arthrometer measurements, or stairs hopple test results. The subjective result and the single-legged hop test result were better for the hamstring tendon group after 6 and 12 months, but no differences were found after 24 months. The hamstring tendon group showed better isokinetic knee extension strength than did the patellar tendon group after 6 months, but not after 12 and 24 months. There was a significant weakness in isokinetic knee flexion strength among the hamstring tendon group. Anterior knee pain was not significantly different between the groups, but kneeling pain was significantly less common in the hamstring tendon group after 24 months.

Association of coronary heart disease with age-adjusted aortocoronary calcification in patients with familial hypercholesterolaemia.

OBJECTIVES: Existing algorithms of risk of coronary heart disease (CHD) do not pertain to patients with familial hypercholesterolaemia (FH), whose arteries have been exposed to hypercholesterolaemia since birth. We studied a cohort of FH patients to compare four diagnostic models of CHD: traditional risk factors of CHD (age, sex, cholesterol, hypertension, smoking and body mass index), cholesterol year score, and aortic as well as coronary calcium measured by spiral computed tomography (CT). SUBJECTS: We invited 88 individuals with molecularly defined FH of whom 80 (91%) decided to participate. RESULTS: Analysis of receiver operating characteristic curves showed that the age-adjusted coronary calcium score was more strongly associated with clinical manifestations of CHD than were traditional risk factors (P < 0.002), cholesterol year score (P << 0.0001), and the age-adjusted aortic calcium score (P < 0.0004). CONCLUSIONS: Age-adjusted coronary calcium score shows promise as an indicator of CHD in FH patients.

Flow cytometric assessment of effects of fluvastatin on low-density lipoprotein receptor activity in stimulated T-lymphocytes from patients with heterozygous familial hypercholesterolemia.

To test the effects of fluvastatin on low-density lipoprotein (LDL) receptor activity in patients with heterozygous familial hypercholesterolemia, the authors measured LDL receptor activity in stimulated T-lymphocytes prepared from 34 patients before and after treatment with 40 mg fluvastatin daily for 12 weeks. Maximally induced pretreatment LDL receptor activities did not correlate with pretreatment plasma cholesterol levels or with changes in plasma cholesterol levels during treatment, and there were no significant changes in LDL receptor activity during treatment. Barring methodological problems, two explanations are possible. Insofar that LDL receptor activity in lymphocytes reflects LDL receptor activity in the liver, the results suggest that the primary response to treatment with fluvastatin in heterozygous familial hypercholesterolemia (FH) patients is not enhanced LDL receptor activity. Alternatively, fluvastatin increases LDL receptor activity in hepatocytes but has little effect on receptor-dependent lipoprotein catabolism in extrahepatic tissues in vivo.

Functional characterization of two low density lipoprotein receptor gene mutations by fluorescence flow cytometric assessment of receptor activity in stimulated human T-lymphocytes.

We report a functional characterization of the W23X and W66G low density lipoprotein (LDL) receptor gene mutations. The authors used two-color fluorescence flow cytometry to measure LDL receptor activity in stimulated T-lymphocytes, prepared from patients heterozygous for the W23X or W66G mutation, and compared the results with measurements of LDL receptor activity in stimulated T-lymphocytes prepared from unrelated healthy control subjects. It was found that the W23X mutation significantly reduced LDL receptor expression and LDL binding and internalization, and that the W66G mutation significantly reduced LDL receptor expression and LDL binding. LDL internalization in patients heterozygous for the W66G mutation was not significantly reduced. The data support the concepts that the W23X mutation prevents production of LDL receptors (class I) and that the W66G mutation produces LDL receptors unable to recycle normally in cells (class V).

Spectrum of LDL receptor gene mutations in Denmark: implications for molecular diagnostic strategy in heterozygous familial hypercholesterolemia.

Heterozygous familial hypercholesterolemia (FH) is one of the most common potentially fatal single-gene diseases leading to premature coronary artery disease, but the majority of heterozygous FH patients have not been diagnosed. FH is due to mutations in the gene coding for the low-density lipoprotein (LDL) receptor, and molecular genetic diagnosis may facilitate identification of more FH subjects. The Danish spectrum of 29 different mutations, five of which account for almost half of heterozygous FH, is intermediate between that of countries such as South Africa, where three mutations cause 95% of heterozygous FH in the Afrikaners, and Germany or England, where there are many more mutations. In clinical practice, a strategy for the genetic diagnosis of heterozygous FH, tailored to the mutational spectrum of patients likely to be seen at the particular hospital/region of the country, will be more efficient than screening of the whole LDL receptor gene by techniques such as single-strand conformation polymorphism (SSCP) analysis in every heterozygous FH candidate. In Aarhus, Denmark, we have chosen to examine all heterozygous FH candidates for the five most common LDL receptor gene mutations (W23X, W66G, W556S, 313 + 1G --> A, 1846 - 1G --> A) and the apoB-3500 mutation by rapid restriction fragment analysis. Negative samples are examined for other mutations by SSCP analysis followed by DNA sequencing of the exon indicated by SSCP to contain a mutation. If no point mutation or small insertion/deletion is detected, Southern blot or Long PCR analysis is performed to look for the presence of large gene rearrangements. In conclusion, our data suggest that an efficient molecular diagnostic strategy depends on the composition of common and rare mutations in a population.

Intronic mutations at splice junctions in the low-density lipoprotein receptor gene.

Most of the low-density lipoprotein receptor (LDLR) gene mutations causing familial hypercholesterolemia (FH) have been identified in the coding region of the gene. We have screened 180 patients for disease-related gene defects and report the identification of three previously described (IVS3+1G-->A, IVS9-1G-->A and IVS16-2A-->G) and two novel mutations (IVS2+1G-->A and IVS14+1G-->T) at splice junctions. Approximately 9% (38/404) of LDLR gene point mutations identified to date in FH patients occur in introns and may affect splicing. The severe consequences of these mutations make them an important target for the molecular analysis of FH.

P1A1/A2 polymorphism of platelet glycoprotein IIIa and risk of acute coronary syndromes in heterozygous familial hypercholesterolemia.

Familial hypercholesterolemia (FH) is an autosomal inherited disorder caused by different mutations in the low density lipoprotein (LDL) receptor gene. It has been demonstrated that there is an increased risk of coronary heart disease (CHD) in heterozygous FH subjects, although this excess CHD is not only explained by the LDL-cholesterol concentration or the class of the LDL-receptor mutation. To investigate if a common polymorphism at the platelet glycoprotein (GP) IIIa gene locus could be related to CHD phenotypic variation in heterozygous FH. we have carried out a case-control study. We have studied 40 cases and 40 controls matched for age, sex and genetic defect in the LDL-receptor gene. Allele frequency of PI(A2) polymorphism for cases and controls was 20 and 22.5%, respectively, and the difference was not significant. In conclusion, our data do not support any association between the GP IIIa polymorphism and the increased prevalence of acute coronary syndromes in the heterozygous FH subjects.

Linking genotype to aorto-coronary atherosclerosis: a model using familial hypercholesterolemia and aorto-coronary calcification.

Most studies of the pathogenesis of coronary heart disease occur between gene variants and biochemical or physiological variables known to be atherogenic. In many situations, however, the gene products are not necessarily known. We studied 17 families (n = 122) with mutations in the low density lipoprotein (LDL) receptor gene as a model in which to test formally for linkage directly between an atherogenic genotype and ischemic heart disease (IHD) or aorto-coronary calcified atherosclerosis. In each family one of three different mutations was found: the Trp66-Gly mutation, the Trp23-Stop mutation, or a ten kilobase deletion removing exons 3-6 of the LDL receptor gene. Genomic DNA was used to determine these mutations by either enzymatic cleavage assays or Southern blotting. Aorto-coronary calcification was significantly associated with age and plasma cholesterol. Sex, hypertension, BMI and smoking were not associated with aorto-coronary calcification. Nonparametric analysis indicated significant linkage of the LDL receptor gene locus to aortic (p < 0.00005) and to aorto-coronary calcified atherosclerosis (p < 0.00001). Assuming a dominant mode of inheritance, significant linkage was detected for aortic (LOD = 3.89) and aorto-coronary calcified atherosclerosis (LOD = 4.10). We suggest that the atherogenicity of variations in other genes could be assessed by a similar approach.

Normolipidemia and hypercholesterolemia in persons heterozygous for the same 1592 + 5G --> A splice site mutation in the low-density lipoprotein receptor gene.

In the present study, we have characterized a unique splice donor G to A substitution in the moderately conserved + 5 position in intron 10 of the low-density lipoprotein (LDL) receptor gene. In two Danish families, carriers of the 1592 + 5G --> A mutation display a clinical phenotype ranging from healthy normocholesterolemic persons to classical heterozygous familial hypercholesterolemia (FH) patients. Reverse transcription-polymerase chain reaction (RT-PCR) of RNA from Epstein Barr virus (EBV)-transformed lymphoblasts obtained from members of both families demonstrated abnormal splicing generating two aberrant mRNAs due to either alternative splicing and skipping of exon 10 or activation of a cryptic splice site in intron 10 inserting 66 intronic base pairs. These abnormally spliced mRNAs were predicted to encode two abnormal receptor proteins containing an in-frame deletion of 75 amino acids and an insertion of 22 novel amino acids, respectively. Results obtained by immunofluorescence staining, flow cytometry, and confocal microscopy of transfected Chang and COS-7 cells expressing normal and mutant LDL receptors were compatible with nearly complete retention of the mutant proteins in the endoplasmic reticulum. Quantitative measurements of LDL receptor mRNAs from EBV-transformed lymphoblasts, however, did not reveal any significant differences in variant mRNA contents between mutation carriers in the families that could be related to degree of hypercholesterolemia.

[Attitude of patients toward detection of hereditary disease. Heterozygote familial hypercholesterolemia]. / Patienters holdning til opsporing af arvelig sygdom. Heterozygot familiaer hyperkolesterolaemi.

Molecular biology has enabled us to identify apparently healthy persons at high risk of genetic disease. The purpose of the present study was to examine attitudes to detection of disease and the present well-being in persons at risk of disease with a modifiable outcome-heterozygous Familial Hypercholesterolaemia (heFH). A questionnaire collecting information on impact on well-being and on attitudes to screening family members for heFH was mailed to heFH index patients and hypercholesterolaemic relatives. Anxiety was expressed by 44%, fear of ischaemic heart disease by 37% and diminished well-being by 13% of respondents. Six percent regretted that they were aware of their diagnosis, and 84% were in favour of screening their family. We conclude that a substantial proportion of persons with heFH experience anxiety due to heFH. A small minority regret being informed of the diagnosis of heFH, however, and a majority are in favour of family screening.

Flow cytometry with a monoclonal antibody to the low density lipoprotein receptor compared with gene mutation detection in diagnosis of heterozygous familial hypercholesterolemia.

We used a fluorescence flow cytometry assay with a monoclonal low density lipoprotein (LDL) receptor-specific antibody to detect LDL receptor expression on blood T lymphocytes and monocytes. We prepared peripheral blood mononuclear cells from patients with genetically verified LDL receptor-defective (Trp66-Gly mutation, n = 17) or receptor-negative (Trp23-stop mutation, n = 17) heterozygous familial hypercholesterolemia (FH) and from healthy individuals (n = 24). The cells were stimulated to express the maximum amount of LDL receptor by preincubation in lipoprotein-deficient medium. A dual-labeling technique allowed flow cytometric analysis of LDL receptor expression on cells identified by fluorescently conjugated surface marker antibodies. Knowing the LDL receptor gene mutation of the FH patients allowed us to compare the diagnostic capability of this functional assay with the DNA diagnosis and to validate the assay with molecular genetics instead of clinical indices of heterozygous FH. T lymphocytes expressed more LDL receptors and gave better diagnostic results than monocytes, and cells from patients with either the Trp66-Gly or the Trp23-stop mutation had variable but significantly reduced LDL receptor expression. The data indicate that this fluorescence flow cytometry assay is unsuitable for diagnosis of individual cases of heterozygous FH but that it may be useful for functionally characterizing mutations in the LDL receptor gene.

Identification of recurrent and novel mutations in the LDL receptor gene in Spanish patients with familial hypercholesterolemia. Mutations in brief no. 135. Online.

We used the single strand conformation polymorphism (SSCP) method to investigate 13 apparently unrelated Spanish patients with familial hypercholesterolemia (FH) for mutations in the promoter region and the 18 exons and their flanking intron sequences of the low density lipoprotein (LDL) receptor gene. We found 16 aberrant SSCP patterns, and the underlying mutations were characterized by DNA sequencing. Five novel missense mutations, Q71E, C74G, C95R, C281Y and D679E, and one nonsense mutation, Q133X, were identified. We also found six missense mutations, S156L, D200Y, D200G, E256K, T413K and C646Y, and one stop codon mutation, W(-18)X, that were previously described in patients from other populations. A new frameshift mutation, 2085del19, was found in one patient. We also identified three splicing mutations; two of them are novel mutations, 1706-10G->A and 2390-1G->A, and the other one has been reported recently, 313+1G->C. Four patients were found to carry two different mutations in the same allele: Q71E and 313+1G->C; C95R and D679E; W(-18)X and E256K, and C281Y and 1706-10G->A. Our results demonstrate that there is a broad spectrum of mutations in the LDL receptor gene in the Spanish population.

Recombinant uracil phosphoribosyltransferase from the thermophile Bacillus caldolyticus: expression, purification, and partial characterization.

The upp gene encoding the major uracil phosphoribosyltransferase (UPRT) of the thermophile Bacillus caldolyticus was cloned by complementation of an Escherichia coli upp mutation. The nucleotide sequence of the cloned DNA revealed an open reading frame of 630 bp encoding a polypeptide of 209 amino acids (M(r) 22,817) with 84% amino acid sequence identity to the deduced upp gene product of Bacillus subtilis. Primer extension analysis indicated that the transcriptional start site of the cloned gene was positioned 37 or 38 bp upstream of the coding region. When over-expressed in E. coli, the recombinant UPRT represented approximately 18% of the soluble cellular proteins. The enzyme was purified to homogeneity by two sequential precipitations with 50 mM Na-phosphate, pH 7.0. Gel filtration chromatography indicated that the native enzyme existed as a dimer at high protein concentrations but that it dissociated to a monomeric form on dilution. In dilute solutions the enzyme is highly unstable but can be stabilized by addition of bovine serum albumin. In concentrated solution (> 5 mg/ml) the enzyme is stable for months at 4 degrees C, even in the absence of bovine serum albumin. By comparing the UPRT activity of crude extracts of B. subtilis and B. caldolyticus it was found that the enzyme from B. caldolyticus was considerably more stable toward thermal inactivation than the homologous enzyme from B. subtilis.