Immunocytochemistry of albumin in hepatocytes after overnight starvation and during a diurnal cycle in young rats

Albumin and the fibrinogen-to-albumin ratio: Biomarkers for the acute phase response following total knee arthroplasty

PURPOSE

Complications following total knee arthroplasty (TKA) lead to patient morbidity and cost. While acute phase reactants, such as c-reactive protein (CRP) and fibrinogen, have been used to predict complications following TKA, the extent and duration of changes in albumin levels following TKA are unknown. It is hypothesized that like CRP and fibrinogen, albumin, and the fibrinogen/albumin ratio (FAR) represent useful measures of the acute phase response (APR) following TKA. The purpose of this study was to describe the longitudinal course of albumin and FAR in healthy patients following TKA, relative to established biomarkers, and examine if the variance in albumin or FAR correlates with patient comorbidities.

METHODS

This retrospective cohort study of patients undergoing TKA at a tertiary medical center. CRP, fibrinogen, and albumin values were collected pre- and post-operatively. An age-adjusted Charlson comorbidity index (CCI) was utilized as a measure of patient comorbidity status.

RESULTS

The median preoperative albumin value was 4.3 g/dL, which dropped to 3.6 g/dL on postoperative day 1 following TKA. The albumin value returned to 93% of the baseline by postoperative week 2. The course of albumin inversely mirrored the course of CRP (r = -0.41). Median preoperative FAR was 0.087 g/L, which rose to 0.130 g/L by postoperative week 2 and returned to baseline by postoperative week 6. While preoperative FAR strongly correlated with postoperative week 2 values (r = 0.74), there was a weak positive correlation between age-adjusted CCI and pre-operative FAR (r = 0.24) in patients undergoing primary TKA.

CONCLUSION

Albumin levels follow a predictable postoperative decline that inversely correlates with CRP in healthy patients following TKA. Given the low cost and abundance of laboratories offering albumin levels, direct albumin levels and/or albumin ratios such as FAR may be underutilized biomarkers for monitoring the APR following TKA.

Immunohistochemical demonstration of interleukin-1 beta induced changes in acute-phase proteins and albumin in rat liver

Interleukin-1 beta is a potent mediator of the acute-phase response. However, the effects of interleukin-1 beta administration on the topic in vivo production of acute-phase proteins and albumin are so far not well understood. Overnight fasted rats were subcutaneously injected with 0.2 mL 0.9% NaCl (control group) or 6.25 micrograms recombinant human interleukin-1 beta, and rectal temperature was measured at intervals up to 48 h. Livers were perfused-fixed in vivo prior to injection (base-line), and at 9, 24, and 48 h following the interleukin-1 beta injection. Fibrinogen, orosomucoid (alpha 1-acid glycoprotein) and albumin were immunostained using a streptavidin-biotin-immunoperoxidase technique. Rectal temperature peaked 5 h after the single interleukin-1 beta injection, and fell gradually to base-line values by 24 h. Prior to injection only a few hepatocytes, randomly scattered throughout the liver lobule, stained positive for fibrinogen and orosomucoid. In contrast, all hepatocytes stained uniformly positive for fibrinogen and orosomucoid 9 h after interleukin-1 beta injection, whereas at 24 h a predominant centrilobular staining pattern occurred. Due to fasting, albumin positive hepatocytes were already reduced at base-line in both groups. Interleukin-1 beta induced a further significant loss of albumin positive cells in the periportal zone (35 +/- 21%) at 9 h when compared with controls (58 +/- 11%, p = 0.037). In conclusion, subcutaneous interleukin-1 beta (probably by stimulation of interleukin-6) strongly induces fibrinogen and orosomucoid expression in rat liver, and suppresses immunohistochemically stainable albumin in a heterogenous way, mainly in the periportal zone.

Metabolic zonation of the liver: regulation and implications for liver function

Liver parenchyma shows a remarkable heterogeneity of the hepatocytes along the porto-central axis with respect to ultrastructure and enzyme activities resulting in different cellular functions within different zones of the liver lobuli. According to the concept of metabolic zonation, the spatial organization of the various metabolic pathways and functions forms the basis for the efficient adaptation of liver metabolism to the different nutritional requirements of the whole organism in different metabolic states. The present review summarizes current knowledge about this heterogeneity, its development and determination, as well as about its significance for the understanding of all aspects of liver function and pathology, especially of intermediary metabolism, biotransformation of drugs and zonal toxicity of hepatotoxins.

Variations in immunoreactivity of angiotensinogen and cathepsins B and H in rat hepatocytes over 24 hours

To examine variations in immunoreactivity of angiotensinogen and cathepsins B and H in hepatocytes over 24 hr, rat liver was examined immunohistochemically. Immunoreactivity of angiotensinogen and cathepsins B and H in periportal and perivenous hepatocytes varied significantly over 24 hr, when analyzed by an image analyzer. In periportal and perivenous hepatocytes, immunoreactivity of angiotensinogen was highest at 0800 hr and lowest at 2000 hr or 0000 hr, whereas that of cathepsins B and H was maximal at 1600 hr and minimal at 0400 hr or 0800 hr. Proteolytic activities of cathepsins B and H in liver extracts varied in parallel to the variations in immunoreactivity of these enzymes. Localization of angiotensinogen in the liver acinus was inversely correlated to that of cathepsins B and H; angiotensinogen was predominantly localized in periportal hepatocytes, but cathepsins B and H were in perivenous hepatocytes at each time point examined. These results suggest that angiotensinogen in hepatocytes is actively synthesized and secreted early in the light period, whereas proteolytic activities in lysosomes of hepatocytes are augmented late in the light period.

Diurnal variation in 5'-nucleotidase activity in rat liver. A quantitative histochemical study

The diurnal variation of 5'-nucleotidase activity in periportal and pericentral areas of rat liver parenchyma has been determined with quantitative histochemical means. 5'-Nucleotidase activity was estimated using microdensitometry in cryostat sections after being incubated with a medium according to Wachstein and Meisel (1957). It appeared that 5'-nucleotidase activity was significantly higher in pericentral areas than in periportal areas throughout the daily cycle and showed a maximum at the end of the light period. It was concluded that 5'-nucleotidase activity may be related with the capacity to diminish messenger RNA resulting in protein breakdown.