The phrase "a first study demonstrated" is correct and usable in written English.
It can be used when introducing findings or results from an initial research study.
Example: "In the field of psychology, a first study demonstrated the impact of sleep on cognitive performance."
Alternatives: "an initial study showed" or "a preliminary study revealed".
A first study demonstrated that the bilateral application of 300 μg per nostril, repeated to reach a complete desensitization, induced a significant reduction and disappearance of the attacks, while a second study demonstrated that the application in the ipsilateral nostril is equally efficacious, whereas the application in the contralateral nostril was ineffective [307, 308].
The interesting correlations between hemochromatosis and celiac disease: a first study demonstrated that occult celiac disease prevents penetrance of hemochromatosis [ 21]; later, it was evidenced that the C282Y mutation of HFE gene may mitigate the severity of celiac disease [ 22], and finally a large case-control study concluded that hemochromatosis predispose to celiac disease [ 23].
A third study demonstrated that POCUS did not improve upon the already optimal test characteristics of clinical examination alone when physicians were certain of their diagnosis; however, POCUS may be of use in cases of clinical uncertainty [310].
A second study demonstrated that this effect is related to how strongly people wanted their party to win.
A second study demonstrated that neutralization of DLL4 during respiratory syncytial viral infection increased Th2 cytokine production as well 45.
In contrast to this, a fourth study demonstrated that patients treated with sequential compression devices experienced fewer events when compared to a control group (0% vs. 11.1%).
A third study demonstrated the feasibility of a 12 week community based program for out-patient children with any type of cancer.
A second study demonstrated that only 25% (2/8) of breast cancer metastases expressing NIS protein had clinically evident radionuclide uptake [ 9].
A third study demonstrated that home-based therapy results in significant improvements in QOL compared with hospital-based therapy in the palliative setting (Payne, 1992).
In addition, while the present article was under preparation, a second study demonstrated independently that 2610029G23Rik escapes X-inactivation in a hybrid Mus musculus × Mus spretus cell line [ 43].
A second study demonstrated that genistein is able to downregulate the levels of the chemokine receptors CXCR4 and CXCL12 when the breast cancer cells were treated with low micromolar concentrations of genistein [ 162].
